Ultrasonic Advisors Blog

Easy Closed-Loop Control of Ultrasonic Transducers with Analog Discovery

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 30 Jun 2025 18:05:28 GMT

I hosted a webinar on June 27, 2025 on

" Easy Closed-Loop Control of Ultrasonic Transducers with Analog Discovery "

You can watch the recording on my YouTube Channel here:

Resources:

Summary

In this webinar, Dr. Husain Shekhani introduces methods for achieving closed-loop control of ultrasonic transducers using WaveForms scripting and Analog Discovery. Topics include dual-loop feedback control, scripting techniques, live demonstrations, and practical troubleshooting tips.

⏱️ TIMESTAMPS:

00:00 Introduction and welcome

01:55 Why closed-loop control matters

04:48 Hardware setup overview

07:50 Scripting foundations in WaveForms

10:40 Dual control objectives explained

14:32 Script block 1 – Fixed drive with measurement

18:20 Script block 2 – Closed-loop voltage control

22:15 Script block 3 – Closed-loop phase control

26:47 Integrated dual-loop control

30:22 Live demo: Real-time control

34:51 Troubleshooting common issues

38:44 Advanced topics and future ideas

41:09 Q&A session

Sponsor information

This webinar was sponsored by PI Ceramic Technology. Learn more about their piezo ceramic products at this link: https://www.piceramic.com/?utm_medium=web&utm_source=UltrasonicAdvisors&utm_campaign=ONLB_700x200_UltrasonicAdvisors_2024-0101-D181_PIC-HP

Beyond PZT: Navigating the Transition to Lead-Free Piezoceramics — Featuring Expert Insights from PI Ceramic

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 28 Mar 2025 20:09:15 GMT

I hosted a webinar on March 21, 2025 on

" Beyond PZT: Navigating the Transition to Lead-Free Piezoceramics — Featuring Expert Insights from PI Ceramic "

You can watch the recording on my YouTube Channel here:

https://youtu.be/2ugy16KGI4g?si=eFHa1QdxSPOaZ3hh

Summary

In this webinar, Dr. Husain Shekhani hosts Dr.-ing Franz Schubert from PI Ceramic to explore the challenges and opportunities in transitioning from lead-based to lead-free piezoelectric materials. Learn about the current regulatory landscape, promising material alternatives, and practical applications where lead-free solutions already excel.

⏱️ TIMESTAMPS:

00:00 Introduction and welcome

01:30 About PI Ceramic and lead-free development history

04:28 RoHS regulations overview and upcoming changes

14:08 Lead-free material alternatives: KNN and BNT families

23:05 Material properties comparison with PZT

26:57 Promising applications for lead-free materials

30:14 Challenges with semi-static applications

33:30 Upscaling production of lead-free materials

40:30 Examples of resonant applications

49:52 Ecological footprint considerations

52:29 Summary and conclusion

56:40 Q&A session

Sponsor information

The Significance of Ultrasonic Transducer Anti-Resonance

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 24 Feb 2025 17:02:21 GMT

I hosted a webinar on November 1, 2024 on

" The Significance of Ultrasonic Transducer Anti-Resonance "

You can watch the recording on my YouTube Channel here:

https://youtu.be/o6cAVyyVnbg

Here is a link to the pdf slides:

significance - antiresonance slides pdf

Summary

In this webinar, Dr. Husain Shekhani explains why anti-resonance matters in ultrasonic transducers, even for systems operating at resonance. Learn how measurements and simulations of anti-resonance can diagnose critical issues and optimize designs.

⏱️ TIMESTAMPS:

00:00 Introduction to anti-resonance significance

01:51 About PI Ceramic (sponsor) and Ultrasonic Advisors

04:16 What is anti-resonance? Basic theory

06:12 Anti-resonance vs. resonance operating principles

09:23 Displacement control and damping effects

12:25 Why measure anti-resonance? Coupling factor analysis

14:54 Using anti-resonance to diagnose electrical issues

17:27 Effects of circuit components on anti-resonance

20:58 Simulation techniques using eigenfrequency analysis

23:36 Free modal analysis software demonstration

26:31 Electrodes and anti-resonance: theoretical perspective

31:34 Q&A session

Sponsor information

*** Announcement ***

My next webinar will be on Friday, March 21, 2025 at 11AM EST.

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

A Comprehensive Overview to Piezoelectric and Ultrasonic Transducers

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 29 Jan 2025 16:08:55 GMT

Piezoelectric and ultrasonic transducers represent a fascinating intersection of materials science and practical engineering applications. Despite their widespread use in modern technology, from medical devices to consumer electronics, these components often remain poorly understood outside specialized fields. This comprehensive guide aims to demystify piezoelectric materials and their applications in ultrasonic transducers, providing both theoretical understanding and practical insights.

Understanding Piezoelectricity

Piezoelectricity, derived from the Greek word "piezo" meaning pressure, describes a unique property where certain materials generate electrical charges when mechanical pressure is applied. More importantly, these materials exhibit what's known as the converse piezoelectric effect - they change shape when an electrical field is applied. This bidirectional energy conversion makes piezoelectric materials particularly valuable in both sensing and actuation applications.

The Science Behind Piezoelectric Materials

What makes piezoelectric materials special is their non-centrosymmetric crystal structure. Unlike most materials, where positive and negative charges cancel each other out under deformation, piezoelectric materials have an asymmetric arrangement of ions that creates a net dipole moment when stressed. This asymmetry is crucial - it's why only certain materials exhibit piezoelectric properties.

The crystal structure of piezoelectric materials features asymmetrically positioned ions with varying bond strengths between different atomic planes. This arrangement creates distinct positive and negative charge centers that separate under stress, resulting in a permanent dipole moment that can be reoriented with an electric field. The most commonly used piezoelectric material today is PZT (Lead Zirconate Titanate), a synthetic ceramic material. While natural piezoelectric materials like quartz exist, their properties are generally too weak for practical applications.

Practical Applications and Limitations

The practical applications of piezoelectric materials are defined by their fundamental characteristics. In terms of displacement, a typical piezoelectric element might only move 0.4 microns when subjected to 1000 volts. While this may seem insignificant, this precise control makes them perfect for nano-positioning applications. Despite small displacements, these materials can generate substantial forces, making them excellent for high-precision, high-force applications.

When compressed, piezoelectric materials can generate substantial voltages - a small piece of PZT can generate over 1800 volts under moderate pressure. This property makes them excellent for sensing and energy harvesting applications.

Medical Applications

In the medical field, piezoelectric technology has revolutionized several areas. Diagnostic imaging relies heavily on ultrasound devices for everything from fetal monitoring to cardiac assessment. Therapeutic tools include surgical instruments for precise cutting, dental cleaning equipment, and lithotripsy devices for kidney stone treatment. In laboratory settings, piezoelectric devices enable cell manipulation, micro-fluid handling, and acoustic microscopy.

Industrial Applications

The industrial sector leverages piezoelectric technology for quality control through non-destructive testing, thickness gauging, and flaw detection systems. Manufacturing processes benefit from ultrasonic welding systems and wire bonding in semiconductor production. Precision positioning systems and ultrasonic cleaning equipment have become indispensable in modern manufacturing facilities.

Consumer Electronics Integration

In consumer electronics, piezoelectric technology enables numerous everyday functions. Audio applications include speakers, microphones, and buzzers. Imaging systems utilize piezoelectric elements for camera autofocus mechanisms and image stabilization. Home appliances incorporate these materials in electronic ignition systems, humidifiers, and cleaning devices.

Piezoelectric vs Electromagnetic Devices: A Comparison

Piezoelectric devices offer several distinct advantages over their electromagnetic counterparts. Their simpler construction requires fewer components and eliminates the need for magnetic materials, resulting in reduced assembly complexity. Perhaps most significantly, piezoelectric devices maintain their efficiency at smaller scales, while electromagnetic devices face significant challenges with miniaturization.

The fundamental difference in drive characteristics - voltage-driven for piezoelectric versus current-driven for electromagnetic - leads to different power supply requirements and control system needs. Piezoelectric devices excel at high frequencies, offering better bandwidth and more precise control in high-speed applications.

Design Considerations and Engineering Challenges

Successful implementation of piezoelectric technology requires careful attention to several key design factors. Mechanical design must account for the fact that piezoelectric ceramics perform better under compression than tension. This often necessitates pre-compression in the design and careful consideration of thermal expansion effects. Displacement enhancement might involve ultrasonic resonators, multi-layer actuators, or mechanical amplification systems, depending on the application requirements.

Material selection presents its own set of challenges. While PZT dominates current applications, environmental concerns about its lead content drive ongoing research into alternatives. Temperature limitations and aging effects must be carefully considered in design specifications. High-power applications require particular attention to heat generation and cooling system integration.

Future Trends and Innovations

The field of piezoelectric technology continues to evolve, with several exciting developments on the horizon. Material innovation focuses on developing lead-free alternatives with improved sustainability and performance characteristics. New applications emerge regularly, particularly in medical technology, where microfluidic cell processing and targeted drug delivery systems show promise.

Manufacturing advances are making production more efficient through improved quality control and automated assembly processes. Integration methods continue to evolve, with better packaging solutions and enhanced reliability becoming standard features of modern designs.

System Integration and Control

Successful implementation of piezoelectric technology requires sophisticated electronic integration and control systems. High-voltage amplifiers, digital control systems, and protection circuits must work in concert to ensure optimal performance. Signal conditioning, noise reduction, and real-time processing capabilities are essential for sensing applications.

Control strategies have evolved to include sophisticated position and force control systems, often incorporating adaptive methods to maintain performance under varying conditions. System optimization increasingly focuses on efficiency improvement and reliability assurance while maintaining cost-effectiveness.

Conclusion

Piezoelectric and ultrasonic transducers represent a crucial technology in modern engineering, offering unique advantages in specific applications. While they may not replace electromagnetic devices in all scenarios, their particular strengths - precision, simplicity, and efficiency at small scales - make them irreplaceable in many critical applications.

The future of piezoelectric technology looks promising, with ongoing developments in materials science, manufacturing techniques, and application areas. As we continue to push the boundaries of what's possible with these remarkable materials, we can expect to see even more innovative applications and improved performance in existing systems.

For engineers and researchers working in this field, staying current with the latest developments while maintaining a solid understanding of the fundamental principles will be crucial for developing the next generation of piezoelectric and ultrasonic devices.

Future Trends in Ultrasonic Technology

Based on my experience with cutting-edge applications, I see several emerging trends in power ultrasonics. Medical devices are moving toward higher frequencies and more precise control, while industrial applications are pushing power limits higher. These trends create new challenges in thermal management and material selection.

When to Seek Expert Help

While this guide provides a solid foundation, some situations benefit from specialized expertise:

When developing novel applications
When scaling up for production
When troubleshooting persistent issues
When optimizing existing designs

About the Author: Dr. Husain Shekhani is the founder of Ultrasonic Advisors, specializing in ultrasonic transducer design and consulting. With extensive experience in medical devices, industrial equipment, and research applications, he helps companies overcome technical challenges and optimize their ultrasonic systems.

Power Ultrasonic Transducer Design Guide: From Theory to Implementation

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 29 Jan 2025 15:38:47 GMT

As an ultrasonic technology consultant with extensive experience in medical devices and industrial applications, I've observed that power ultrasonic transducers often present unique challenges to engineering teams. Whether you're developing surgical instruments, welding equipment, or cleaning systems, understanding these sophisticated devices is crucial for project success. In this comprehensive guide, I'll share practical insights gained from years of hands-on experience in transducer development and troubleshooting.

What Are Power Ultrasonic Transducers?

Think of a power ultrasonic transducer as a highly specialized speaker that operates at frequencies far above human hearing. Instead of producing sound waves, these devices convert electrical energy into powerful mechanical vibrations that can cut tissue, weld plastics, or clean surfaces. Unlike their low-power cousins used in medical imaging, power ultrasonic transducers typically operate from tens of watts to kilowatts, making their design considerably more challenging.

Why Companies Choose Ultrasonic Technology

In my consulting work, I frequently see teams exploring ultrasonic solutions for challenging problems. The technology offers unique advantages that are difficult to achieve through other means. For instance, ultrasonic surgical tools can precisely emulsify tissue while minimizing damage to surrounding areas. In manufacturing, ultrasonic welding creates strong bonds between plastics without external heat sources. These capabilities stem from the unique physical phenomena that occur at ultrasonic frequencies.

Understanding the Core Components

The heart of every power ultrasonic system is the bolt-clamped (Langevin) transducer. Having worked on numerous designs from prototype to production, I can tell you that each component plays a crucial role in overall performance.

The Central Bolt: More Than Just a Fastener

Many engineers initially underestimate the importance of the central bolt. It's not just holding things together – it's maintaining crucial compression on the piezoelectric crystals. I've seen numerous transducer failures traced back to improper bolt selection or assembly. The bolt must be carefully sized and properly torqued to maintain compression while allowing the crystals to vibrate efficiently.

Back Mass: The Hidden Performance Driver

The back mass might look like a simple metal cylinder, but its design significantly impacts transducer performance. In my experience, material selection here is crucial. While steel is common, I've achieved excellent results using tungsten in high-performance applications where cost isn't the primary concern. The back mass's role in reflecting sound waves and distributing preload force makes it a critical component for optimization.

The Horn: Where Theory Meets Practice

Horn design is where many projects encounter their first major challenges. While theoretical calculations might suggest one approach, practical considerations often demand compromises. I've found that successful horn design requires balancing mathematical models with real-world constraints like manufacturing capabilities and material properties. The horn's profile – whether stepped or tapered – must be carefully optimized for each application.

Common Design Challenges and Solutions

Through years of consulting, I've encountered several recurring challenges in transducer development. Here are some key insights that can save you time and resources:

Crystal Stack Design

The piezoelectric crystal stack is the power generator of your transducer. Many teams struggle with determining the optimal number of crystals and their arrangement. While larger crystal volume generally means more power capability, simply adding more crystals isn't always the answer. I've found that careful consideration of voltage requirements, power density, and thermal management often leads to better solutions than brute-force approaches.

Managing Stress Distribution

One of the most common failure modes I encounter involves uneven stress distribution. The static preload from the bolt must work in harmony with the dynamic stresses during operation. Through careful design and assembly practices, we can achieve a more uniform stress distribution that significantly improves reliability.

The Assembly Process: Where Success Is Made or Lost

Having supervised countless transducer builds, I can confidently say that assembly is just as critical as design. Here's what you need to know:

Preparation Is Everything

Clean components and precise alignment are non-negotiable. I recommend using a controlled environment and following a detailed cleaning protocol. Simple oversights during cleaning can lead to significant performance variations.

The Critical Preload Step

Achieving the correct preload is both art and science. While theoretical calculations provide a starting point, experience has taught me to pay close attention to torque values and preload voltage measurements during assembly. I've developed specific procedures that consistently achieve optimal results.

Testing and Validation

Beyond Basic Measurements

While impedance measurements are standard practice, I've found that comprehensive testing requires a more nuanced approach. Burn-in testing, in particular, often reveals issues that basic measurements miss. I typically recommend a staged testing protocol that gradually increases power while monitoring multiple parameters.

Future Trends in Ultrasonic Technology

When to Seek Expert Help

While this guide provides a solid foundation, some situations benefit from specialized expertise:

When developing novel applications
When scaling up for production
When troubleshooting persistent issues
When optimizing existing designs

Conclusion

Power ultrasonic transducer development requires a careful balance of theoretical knowledge and practical experience. While the fundamental principles are well established, successful implementation often depends on subtle details and accumulated expertise. Whether you're developing a new product or optimizing an existing design, understanding these concepts will help you achieve better results.

For more detailed guidance or consulting support, feel free to reach out to discuss your specific challenges. With experience across medical, industrial, and research applications, I can help you navigate the complexities of ultrasonic technology development.

Free Ultrasonic Modal Analysis/Resonance Simulation Software/FEA

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 04 Nov 2024 15:53:03 GMT

I hosted a webinar on November 1, 2024 on

" Free Ultrasonic Modal Analysis/Resonance Simulation Software/FEA "

You can watch the recording on my YouTube Channel here:

https://youtu.be/HDiO6t_9ut0?si=S1AFVa0G5jv2ksLo

Here is a link to the software:

https://www.ultrasonicadvisors.com/simulation-software

**AI summary of webinar and software product**

Summary

Husain Shekhani, PHD presents a free ultrasonic transducer simulation software for modal analysis, sponsored by PI Technology, with insights into its features and applications.

Highlights

�� Free software available for ultrasonic transducer simulation!
�� Easy to perform modal analysis and resonance simulations!
��️ Import CAD files and assign materials effortlessly!
�� Generate and solve for eigenfrequencies with quick processing!
�� Iterative design adjustments enhance transducer performance!
�� Expert consulting available for ultrasonic transducer development!
�� Follow-up resources and updates provided via email!

Key Insights

�� Accessibility : The software is free, enabling broader access for engineers and researchers to perform complex simulations without financial barriers.
�� Iterative Design Process : Users can iterate designs based on simulation results, fostering improved understanding and optimization of ultrasonic transducers.
⚙️ User-Friendly : The interface allows easy importation of CAD models and straightforward material assignment, streamlining the simulation setup.
�� Sponsorship and Support : Sponsored by Pi Technology, users gain insights into high-quality ceramic materials that enhance device performance.
�� Consulting Services : Husain offers consulting for companies needing guidance in ultrasonic transducer design, ensuring expert advice is available.
�� Rapid Processing : The software’s efficient solving capabilities mean simulations can be completed quickly, aiding timely project development.
�� Community Engagement : Ongoing webinars and resources help maintain user engagement and provide continuous learning opportunities in the ultrasonic field.

Sponsor information

*** Announcement ***

My next webinar will be on Friday, November 8, 2024 at 11AM EST. I will cover

How to simplify ultrasonic transducer CAD geometry for FEA simulation

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to use impedance measurements from a piezoelectric disk to calculate material properties

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 16 Sep 2024 20:58:37 GMT

I hosted a webinar on September 13, 2024 on

" How to prepare specifications when ordering piezo ceramic elements "

You can watch the recording on my YouTube Channel here:

https://youtu.be/dW6ahW3mH0g

Here is a link to the pdf of the presentation notes:

webinar_28_kp.pdf

KP DISK PIEZO MATERIAL PROPERTY CALCULATOR - to determine material properties from impedance measurements made on a PZT disk

Summary

I explain how to use impedance measurements from piezoelectric disks to calculate material properties, covering resonance modes, experimental setups, and analysis techniques.

Highlights

�� Impedance measurements reveal material properties.
��️ Care in sample holder design is crucial for accuracy.
�� Distinguishing between planar and thickness resonance is essential.
�� Experimental methods for impedance analysis are discussed.
�� Pi Ceramic is highlighted as a reputable supplier.
�� Effective coupling factors can help analyze material properties.
⚙️ Finite element analysis (FEA) aids in property verification.

Key Insights

�� Impedance Analysis : Impedance measurements are key to determining material properties, but require careful setup and analysis to ensure accuracy. Understanding the nuances of the impedance response is critical for valid results.
�� Resonance Modes : Differentiating between planar and thickness resonance modes is vital, as they influence the analysis of piezoelectric properties differently. Each mode has unique characteristics that affect how data is interpreted.
�� Sample Holder Importance : The design of the sample holder significantly impacts measurement repeatability and accuracy, emphasizing the need for precision engineering in experimental setups.
�� Material vs. Disk Properties : It’s essential to distinguish between properties of the piezoelectric disk and the underlying material properties, as they can lead to different conclusions if conflated.
�� Finite Element Analysis (FEA) : Utilizing FEA can provide more accurate simulations and help verify experimental results, particularly when dealing with complex geometries or small samples.
�� Supplier Quality : Choosing high-quality suppliers like Pi Ceramic ensures reliable materials that can withstand rigorous testing, contributing to overall system performance.
�� Capacitance Measurement : Capacitance comparisons can be utilized across different geometries, providing a versatile method for evaluating piezoelectric materials regardless of shape or size.

Sponsor information

*** Announcement ***

My next webinar will be on Friday, October 18, 2024 at 11AM EST. I will cover

Ultrasonic Advisors' Transducer Simulation Software

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

kp Piezo Disk Material Property Calculator

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 16 Sep 2024 18:19:30 GMT

Calculator

Piezo disk impedance to material property calculator

Video recording walkthrough of calculator: Link to video

How to prepare specifications when ordering piezo ceramic elements

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 28 Jun 2024 16:26:01 GMT

I hosted a webinar on June 21, 2024 on

" How to prepare specifications when ordering piezo ceramic elements "

You can watch the recording on my YouTube Channel here:

https://youtu.be/DURMwF6_mQI

Here is a link to the pdf of the presentation notes:

Webinar 27 - Piezo specs prep.pdf

Summary

In this webinar, I speak on the following topics:

(1) General view of tolerances/specifications for piezo/PZT ceramic elements

(2) What can we specify? (electrical and mechanical parameters)

(3) Methodology for determining specifications

(4) True ceramic vendor stories

Sponsor information

*** Announcement ***

My next webinar will be on Friday, July 26, 2023 at 11AM EST. I will cover

Using a microphone for ultrasonic transducer analysis

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to analyze electrical impedance properties of piezoelectric sensors

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 30 May 2024 19:47:22 GMT

I hosted a webinar on May 17, 2024 on

" How to analyze electrical impedance properties of piezoelectric sensors "

You can watch the recording on my YouTube Channel here:

https://youtu.be/3ycLAfSXyEE

Here is a link to the pdf of the presentation notes:

Webinar 26 - sensor Piezo.pdf

Summary

In this webinar, I (1) review piezo sensor equations (2) describe how to analyze piezo voltage when external circuits are applied and (3) describe voltage and charge amplifier circuits used to stabilize and amplify the sensor output.

Sponsor information

*** Announcement ***

My next webinar will be on Friday, June 21, 2023 at 11AM EST. I will cover

Piezo sensor analysis on a simulated and prototype circuit

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Introduction to Ultrasonic Assisted Atomizers/Nebulizers/Spray Technology

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 20 May 2024 16:43:22 GMT

I hosted a webinar on February 26, 2024 on

" Introduction to Ultrasonic Assisted Atomizers/Nebulizers/Spray Technology "

You can watch the recording on my YouTube Channel here:

https://youtu.be/rjuZKR5p-EY

Here is a link to the pdf of the presentation notes:

Webinar 25 ultrasonic atomizer spray.pdf

Summary

In this webinar, I described the three different method of ultrasonic atomization/droplet creation. They are: submerged, mesh, and power transducer/nozzle.

Sponsor information

*** Announcement ***

My next webinar will be on Friday, May 17, 2023 at 11AM EST. I will cover

(Topic will change based on LinkedIn poll to come)

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Everything you need to know about designing and assembling power ultrasonic transducers

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 26 Jan 2024 17:28:42 GMT

I hosted a webinar on January 26, 2024 on

" Everything you need to know about designing and assembling power ultrasonic transducers "

You can watch the recording on my YouTube Channel here:

https://youtu.be/oAMjCGBXYms

Here is a link to the pdf of the presentation notes:

Webinar 24 - everything power transducers.pdf

Summary

In this webinar I gave a "catch-all" presentation on bolt-clamped ultrasonic power transducer. Specifically, I discussed:

-How to design a power ultrasonic transducer (bolt-clamped)

-How to assembly the transducer

- How to test the transducer

*** Announcement ***

My next webinar will be on Friday, February 23, 2023 at 11AM EST. I will cover

"How to determine to determine the requirements of your transducer application using an R&D electrical driver” (Topic will change based on LinkedIn poll to come)

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

What happens to the displacement at the antiresonance frequency of an ultrasonic transducer

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 29 Dec 2023 17:28:25 GMT

I hosted a webinar on December 29, 2023 on

" What happens to displacement at the antiresonance frequency of an ultrasonic transducer "

You can watch the recording on my YouTube Channel here:

https://youtu.be/Zj9fXkaEADw

Here is a link to the pdf of the whiteboard notes:

Webinar 23 antiresonance displacement.pdf

Here is a link to the Waveforms workspace file: webinar23_wvforms_displacement.dwf3work

Summary

Using a laser doppler vibrometer, I demonstrate that the mechanical displacement is not affected by the antiresonance phenomenon of ultrasonic transducers.

In this webinar, I show experiments and talk about theory. I also talk about mechanical antiresonance.

*** Announcement ***

My next webinar will be on Friday, January 5, 2023 at 11AM EST. I will cover

"How to measure the accuracy and linearity of an laser doppler vibrometer for ultrasonic transducers”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to use multiple transformers to increase voltage and power delivered to an ultrasonic transducer

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 21 Dec 2023 17:06:22 GMT

I hosted a webinar on December 15, 2023 on

" How to use multiple transformers to increase voltage and power delivered to an ultrasonic transducer "

You can watch the recording on my YouTube Channel here:

https://youtu.be/Xb8JaKivXzw

Here is a link to the pdf of the whiteboard notes: Webinar22_double_transformers pdf

Summary

In this webinar, I (1) Describe the use cases of using 2 or more transformers (2) Demonstrate voltage doubling using two off the shelf transformers

*** Announcement ***

My next webinar will be on Friday, December 29, 2023 at 11AM EST. I will cover

"What is the difference in vibrometer measurements of an ultrasonic transducer at anti-resonance and at resonance”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to make Impedance Measurements of Ultrasonic Transducers with the Digilent Analog Discovery

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 11 Dec 2023 15:55:13 GMT

I hosted a webinar on December 8, 2023 on

" How to make Impedance Measurements of Ultrasonic Transducers with the Digilent Analog Discovery "

You can watch the recording on my YouTube Channel here:

https://youtu.be/B8llEdp1X2o

Here is a link to the pdf of the whiteboard notes: webinar21_digilent_impedance.pdf

Here is a link to the calculation script: analog_discovery_impedance_script.txt

Summary

In this webinar, I show how to make impedance measurements of ultrasonic transducer with the Digilent Analog Discovery.

I go over the following topics:

(1) Overview of hardware

(2) Settings overview and measuring the accuracy of the measurements

(3) Measure impedance response of ultrasonic transducer – like an expert!

*** Announcement ***

My next webinar will be on Friday, December 15, 2023 at 11AM EST. I will cover

"How to use two transformers to double voltage gain in an ultrasonic transducer drive circuit”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to make your own passive AC and DC voltage measurement probes for ultrasonic analysis

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 24 Nov 2023 17:38:35 GMT

I hosted a webinar on November 24, 2023 on

" How to measure the d33 coefficient of a piezo ceramic by applying a force and measuring a voltage "

You can watch the recording on my YouTube Channel here:

https://youtu.be/xvy5jdbIEQQ

Here is a link to the pdf of the whiteboard notes: Webinar 20 notes - custom 10x probe

Summary

In this webinar, I describe the theory of a 10x probe and practically how to make your own very simple 10x probe that does not require any compensation. This is super useful for ultrasonic and audio work.

*** Announcement ***

My next webinar will be on Friday, December 1, 2023 at 11AM EST. I will cover

"How to make impedance measurements of ultrasonic transducers using the Diligent Analog Discovery”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to measure the d33 coefficient of a piezo ceramic by applying a force and measuring a voltage

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 17 Nov 2023 17:33:04 GMT

I hosted a webinar on November 17, 2023 on

" How to measure the d33 coefficient of a piezo ceramic by applying a force and measuring a voltage "

You can watch the recording on my YouTube Channel here:

https://youtu.be/iOslucScEik

Here is a link to the pdf of the whiteboard notes: Webinar 19 d33 notes

Here is a link to the finalized code, which measures voltage and converts it into MPa with the needed inputs: Webinar18_ads1115_20231110122622.zip

Summary

In this webinar, I show how to use an Arduino and the ADS1115 ADC to measure preload voltage of a transducer with high impedance impedance. I have a long discussion about using the ADS1115.

I talk about theory, using the ADS1115, and show live demo and the Arduino code.

*** Announcement ***

My next webinar will be on Friday, November 17, 2023 at 11AM EST. I will cover

"How to measure the d33 coefficient of a piezo crystal using a known applied force”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Force Voltage d33 calculator

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 17 Nov 2023 15:15:33 GMT

Calculator

Preload Calculator

How to use an Arduino to measure preload voltage of ultrasonic transducer and convert to stress

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 10 Nov 2023 17:44:54 GMT

I hosted a webinar on November 10, 2023 on

" How to use an Arduino to measure preload voltage of ultrasonic transducer and convert to stress "

You can watch the recording on my YouTube Channel here:

https://youtu.be/EIgjLZQjZQw

Here is a link to the pdf of the whiteboard notes: Webinar 18 notes

Here is a link to the finalized code, which measures voltage and converts it into MPa with the needed inputs: Webinar18_ads1115_20231110122622.zip

Summary

In this webinar, I show how to use an Arduino and the ADS1115 ADC to measure preload voltage of a transducer with high impedance impedance. I have a long discussion about using the ADS1115.

I talk about theory, using the ADS1115, and show live demo and the Arduino code.

*** Announcement ***

My next webinar will be on Friday, November 17, 2023 at 11AM EST. I will cover

"How to measure the d33 coefficient of a piezo crystal using a known applied force”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Multimeter Modification to achieve Giga-Ohm input impedance for Transducer Preload measurement

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 03 Nov 2023 16:47:04 GMT

I hosted a webinar on November 3, 2023 on

" Preload measurement circuit for bolt-clamped ultrasonic Langevin transducers "

You can watch the recording on my YouTube Channel here:

https://youtu.be/rYcdf0nxfG0

Summary

In this webinar, I show how to modify a multimeter to create a Giga-Ohm input impedance for measuring voltage. Why do this? To create a super stable voltage measurement for measuring transducer preload voltage.

*** Announcement ***

My next webinar will be on Friday, November 10, 2023 at 11AM EST. I will cover

"Using an Arduino/microcontroller to measure transducer preload voltage and convert it into MPA/stress”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Preload measurement circuit for bolt-clamped ultrasonic Langevin transducers

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 27 Oct 2023 16:29:02 GMT

I hosted a webinar on October 27, 2023 on

" Preload measurement circuit for bolt-clamped ultrasonic Langevin transducers "

You can watch the recording on my YouTube Channel here:

https://youtu.be/3DMhhIglg0o

Here is a link to the presentation notes.

Here is a link to the preload calculator that I use during the webinar: Preload Calculator

Topics

In this webinar recording, I show how to measure the preload of an ultrasonic transducer stack transducer using a simple circuit and a multimeter. I provide calculations and a real demonstration.

Video outline

0:29 - Outline of webinar
1:50 - Bolt-clamped transducer components
3:00 - Introduction to my consulting work
9:32 - Why do we preload?
12:52 - Preloading measurement method comparison
17:30 - How to determine the required preload
25:00 - Theory of voltage to preload using a film capacitor circuit
30:00 - 5 benefits of using a film capacitor circuit for charge measurement
35:00 - Introduction to my prestress calculator
37:30 - Choosing a capacitor and time constant
41:30 - Options to measure preload voltage
42:56 - The exact capacitor I recommend
44:00 - Walkthrough of loosening and fastening a transducer and measuring preload voltage and torque
46:22 - Calculation of stress from transducer used in demonstration
47:25 - Weekly webinars on preloading

48:00 - Questions

*** Announcement ***

My next webinar will be on Friday, November 3, 2023 at 11AM EST. I will cover

"High Impedance Multimeter Modification for Ultrasonic Transducer Preload Measurement”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Preload Calculator

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 26 Oct 2023 10:09:55 GMT

Calculator

Preload Calculator

How to use an oscilloscope to make measurements on an ultrasonic transducer system

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 28 Aug 2023 20:07:41 GMT

I hosted a webinar on August 25, 2023 on

" How to use an oscilloscope to make measurements on an ultrasonic transducer system "

You can watch the recording on my YouTube Channel here:

https://youtu.be/3DMhhIglg0o

Here is a link to the presentation notes.

Topics

In this webinar recording, I demonstrate the most required skill when working with ultrasonic transducers - how to use an oscilloscope. This is practically the only way to measure and interpret ultrasonic transducer performance. Its use is priceless in troubleshooting and design.

Video outline:

0:46 - Outline of presentation
2:10 - What is an oscilloscope
6:48 - Introduction to my consulting work
8:20 - USB vs. Bench oscilloscopes
15:30 - Overview of probes
19:00 - 10x probe options
21:00 - 1x probe vs. BNC to clip
22:45 - Differential probe options
24:50 - Equivalent circuit of a 10x probe
26:45 - Compensation capacitor
27:00 - Current clamp probe or voltage probe + resistor for current
28:30 - Recommended oscilloscopes and probes
33:20 - Set up of an oscilloscope
35:11 - Measurement set up
35:40 - Circuit for resistor current measurement
43:15 - Demonstration of the set up of a benchtop oscilloscope
49:30 - How to prove an ultrasonic driver circuit
54:10 - Set up of Picoscope (4-channel USB oscilloscope) for input DC power and output ultrasonic power measurement for steady state analysis. (RMS voltage, current, and power)
59:40 - Set up of Picoscope for transient analysis of ultrasonic signals on a power ultrasonic transducer

*** Announcement ***

My next webinar will be on Friday, September 29, 2023 at 11AM EST. I will cover

"Preload measurement circuit for bolt-clamped ultrasonic Langevin transducers”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to wind a transformer for an ultrasonic transducer drive circuit

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 20 Jul 2023 17:43:00 GMT

I hosted a webinar on July 19, 2023 on

" How to wind a transformer for an ultrasonic transducer drive circuit "

You can watch the recording on my YouTube Channel here:

https://youtu.be/7O_J4rfD_QU

Here is a link to the presentation notes.

Topics

In this webinar recording, I explained the theory, purpose, and process of winding a transformer to achieve more power transfer from a ultrasonic driver to you ultrasonic transducer.

I wound a transformer to step up voltage from a 4 Ohm output amplifier to a 100Ohm load, which was a placeholder for an ultrasonic transducer.

I also discussed various practical topics at the end of the presentation.

Video outline:

0:10 Introduction to topic - transformer
0:50 Presentation outline..
2:00 Ultrasonic Advisors consulting
3:00 Where do transformers fit in the drive circuit?
5:20 Why use a transformer?
7:30 Engineering diagram explanation
10:00 Transformer misconceptions
13:30 Voltage drop and optimal impedance for driver
15:50 Step 1 - Choose a core
18:15 Step 2 - Test your amplifier's desired load
21:45 Step 3 - Determine step up ratio based on target load
23:50 Step 5 - Determine primary and secondary winding numbers
26:40 Step 6 - Wind the transformer and test the inductance and the coupling factor
32:10 Testing the final transformer
34:16 Additional practical topics related to amplifier and transformers
44:43 Topics for future webinars

*** Announcement ***

My next webinar will be on Friday, August 18, 2023 at 11AM EST. I will cover

"Preload measurement circuit for bolt-clamped ultrasonic Langevin transducers”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Current and resonance tracking in an ultrasonic drive circuit with an Arduino

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 19 Jun 2023 02:32:29 GMT

I hosted a webinar on June 16, 2023 on

" Current and resonance tracking in an ultrasonic drive circuit with an Arduino "

You can watch the recording on my YouTube Channel here:

https://youtu.be/9npoCMlmqRM

Here is a link to the presentation notes.

Here is a link to the Arduino code.

Topics

In this webinar recording, I implemented current measurement and frequency and voltage amplitude control to create a feedback loop to track the resonance frequency and also to drive the target current.

I used an Arduino nano, JFET (amplitude control), sine wave generator chip, and an amplifier with a transformer.

Video outline:

0:00 Introduction to the topic
1:00 Pictures of drive circuit and ultrasonic scaler
3:10 Function generator DJ (a joke about manually controlling frequency and amplitude)
4:15 About Ultrasonic Advisors
5:30 Detailed outline
8:20 Quick overview of the drive logic of ultrasonic transducer driver control
11:20 Discussion of the impedance response of an ultrasonic scalpel
15:45 Previous circuit webinars
16:56 Current measurement circuit
19:18 Voltage amplitude control circuit with a P JFET
27:31 Block diagram of drive circuit and logic
28:32 Circuit pictures
30:15 Code overview/Arduino code review
36:24 Drive control logic explanation to search for the resonance frequency based off current measurement
37:20 Explanation of parts (Arduino, sine wave generator IC, amplifier, dental scaler ultrasonic transducer
39:29 Winding transformer
41:21 Live demonstration of circuit via oscilloscope, Arduino serial output, and visual micron displacement measurement
45:00 Displacement measurement at the maximum output of the circuit

*** Announcement ***

My next webinar will be on Friday, July 14, 2023 at 11AM EST. I will cover

"Transformer design for ultrasonic transducers drive circuits”

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to use an ARDUINO to measure phase between voltage and current in an ultrasonic transducer

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 17 Apr 2023 16:15:36 GMT

I hosted a webinar on April 14, 2023 on

" How to use an Arduino to measure phase between voltage and current in an ultrasonic transducer "

You can watch the recording on my YouTube Channel here:

https://youtu.be/2_-4a16gJz4

Here is a link to the presentation notes .

Topics

In this webinar recording, I used a simple circuit to measure the phase angle between voltage and current by converting it to a DC signal. This signal can be read by an Arduino or other microcontroller.

This was accomplished by feeding the voltage and current signals to comparators, and then creating an averaging circuit with a RC filter.

I integrated all of this with an Arduino and I was able to minimize the phase and drive a piezoelectric/ultrasonic mesh atomizer at it's resonance frequency

Video detailed outline:

0:00 - Introduction to webinar topic
1:00 - Outline - (Part 1 Theory, Part 2 Practice)
2:00 - Demonstration of phase tracking of an ultrasonic mesh atomizer
2:45 - Introduction to Ultrasonic Advisors
4:19 - Why measure phase?
11:51 - Circuit to measure phase (convert phase to DC voltage)
17:10 - LT spice simulation demonstration of circuit function
20:26 - Block diagram of ultrasonic driver with phase feedback
21:26 - Generating sine wave using AD9833/AD9837
23:00 - Driving amplifier
25:15 - Transformer
25:40 - How to probe voltage and current and measure phase angle
28:37 - Impedance response of ultrasonic mesh atomizer
29:50 - Oscilloscope view of voltage and current with frequency sweep
31:38 - DC voltage measurement of phase during frequency sweep
33:12 - Arduino measurement of DC phase voltage during frequency sweep
34:12 - Intro to Arduino code for frequency tracking
34:58 - Arduino phase tracking in action
36:50 - Detailed Arduino code explanation
38:17 - Pictures of Arduino and circuit
39:51 - Schematic of actual circuit

*** Announcement ***

My next webinar will be 11AM ET - May 19, 2023 "Implementing dual feedback loops for constant current and constant phase for ultrasonic transducer drive "

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Ultrasonic Transducer Resonance Frequency Tracking using an Arduino

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 17 Mar 2023 20:40:16 GMT

I hosted a webinar on March 10, 2023 on

" Ultrasonic Transducer Resonance Frequency Tracking "

You can watch the recording on my YouTube Channel here:

https://youtu.be/f8sRapa-swM

Here is a link to the presentation notes .

Topics

In this webinar recording, I used an Arduino microcontroller to provide frequency control feedback based on current measurements.

I drove an atomizer transducer at a specified current level. I utilized a frequency generation IC (SI5351), an audio amplifier board to produce 90kHz-110kHz. I also used a hand wound transformer for impedance matching. Finally, a simple peak detect circuit conditioned the current signal to be read by the analog input of the Arduino.

Here is the outline of the webinar.

0:00 -Welcome to my 11th webinar
1:54 -Outline
5:07 -Choosing a transducer
7:47 -About Ultrasonic Advisors
8:57 -Block diagram of feedback circuit
13:25 -Drive circuit principles
18:25 -Feedback control with regards to impedance frequency response
20:39 -Impedance response of mesh atomizer with and without fluid
23:27 -Driving Amplifier
33:30 -Amplify voltage
36:30 -Transformer winding
39:09 -Walk through of experimental circuit setup
46:14 -Final circuit diagram
53:58 -Current peak detect circuit
55:42 -Arduino feedback loop code
59:30 -Oscilloscope readings
1:04:04 -Arduino serial monitor of feedback loop
1:06:02 -Questions and Answers

*** Announcement ***

My next webinar will be 11AM ET - April 14, 2023 "Implementing feedback loops for current and phase in an ultrasonic drive circuit "

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to model losses/damping in ultrasonic transducer COMSOL and ANSYS Simulations

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 13 Feb 2023 16:15:35 GMT

I hosted a webinar on February 10, 2023 on

" How to model losses/damping in ultrasonic transducer COMSOL and ANSYS Simulations "

You can watch the recording on my YouTube Channel here:

https://youtu.be/xmjj108b7WY

Here is a link to the presentation notes and excel calculations .

Topics

In this webinar, I talk about how to implement damping in ultrasonic transducer simulations (i.e frequency response simulations).

I first demonstrate the measurement of the mechanical quality factor using impedance analysis, high power analysis (oscilloscope measurement). I also consider a loaded and unloaded case.

I use the quality factors to input loss parameters and I optimize the representation of losses in the ceramic (PZT crystal), metal (aluminum and steel), and boundary losses (from the load).

I use COMSOL in this analysis, but I the methods also apply to ANSYS.

Here is the outline of the webinar.

0:40 - Webinar outline
1:51 - Quick overview of my consulting services
3:40 - Rehash of webinar outline
7:46 - Importance of damping in simulations
12:50 - Experimental transducer and loading condition
15:09 - Experimental methods (impedance analysis and oscilloscope measurements)
15:34 - Impedance analysis of low power (loaded and unloaded)
19:00 - Oscilloscope analysis for high power (loaded and unloaded)
23:30 - Summary parameters for impedance/admittance and quality factors
32:43 - COMSOL - set up of the simulation - geometry and materials
32:49 - COMSOL - how to represent losses in ANSYS and COMSOL
35:40 - Strategy to tune model losses to reflect low power and high power AND loaded and unloaded losses
40:00 - COMSOL model walk through to analyze material losses and boundary losses

*** Announcement ***

My next webinar will be 11AM ET - March 10, 2023 "Build, test, simulation, and analysis of an ultrasonic atomizer/nebulizer "

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Statistical Analysis for Ultrasonic Transducers

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 16 Jan 2023 20:31:15 GMT

I hosted a webinar on January 13, 2023 on

" Statistical Analysis for Ultrasonic Transducers "

You can watch the recording on my YouTube Channel here:

https://youtu.be/lcHh-FZqso8

Here is a link to the presentation notes and excel calculations .

Topics

In this webinar, I describe how to improve your experiments to ensure that you can confidently make conclusions based off of your ultrasonic transducer experiments.

Here is the outline of the webinar.

0:21 - Intro to the webinar
1:46 - Quick overview of my consulting services
3:00 - Different scenarios requiring a DOE
5:35 - Experimental strategy to get conclusive results
11:45 - How to improve experimental outcomes?
14:32 - Strategy to use statistical methods
19:45 - Determine what change is significant to you?
20:23 - Introduction to the TTEST to determine statistical significance
25:10 - Practical demonstration using Microsoft Excel calculations
28:31 - Sample size calculation using statistical power
32:20 - Different types of TTEST experimental design
34:40 - Other statistical topics for future study
36:05 - Easy statistical analysis in Excel for ultrasonic transducer experiments

*** Announcement ***

My next webinar will be 11AM ET - February 10, 2023 " Behavior of ultrasonic transducer under high power drive/large signal [Topic may change based on feedback]"

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to calculate the equivalent circuit for an ultrasonic transducer from impedance

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 13 Dec 2022 17:56:47 GMT

I hosted a webinar on December 9, 2022 on

" How to calculate the equivalent circuit for an ultrasonic transducer from impedance "

You can watch the recording on my YouTube Channel here:

https://youtu.be/wpi6bnDQePI

Here is a link to the presentation notes and excel calculations .

Topics

In this webinar, I go step by step and use impedance to calculate the equivalent circuit of an ultrasonic transducer. I talk about theory and practical calculations.

Here is the outline of the webinar.

1:47 - Outline
2:20 - What is the equivalent circuit?
8:10 - Physical dynamics and ultrasonic impedance response
13:40 - Why use the equivalent circuit?
23:22 - Outline of how to calculate equivalent circuit
25:00 - Experimental setup
26:00 - Capacitance calculation - Ct
27:27 - Resonance and anti-resonance measurement
29:15 - Calculation of R1
30:50 - Calculation of quality factor Q
35:10 - Calculation of C1
36:00 - Calculation of C0
37:00 - Coupling factor keff from C1, C0, and Ct
39:20 - Calculation of L1
41:22 - Using keff to calculate equivalent circuit properties - alternative method
43:00 - Excel calculations of R1, L1, C1, C0 and impedance response

*** Announcement ***

My next webinar will be 11AM ET - January 13, 2023 " Making real conclusions: analyzing ultrasonic transducer measurements with relevant statistics [Topic may change based on feedback]"

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Capacitance analysis of ultrasonic transducers

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 23 Nov 2022 14:00:00 GMT

I hosted a webinar on November 18, 2022 on

" Parameters to measure in ultrasonic transducer impedance analysis "

You can watch the recording on my YouTube Channel here:

https://youtu.be/4qUYmYwpCBQ

Here is a link to the presentation notes: Lin k

Topics

In this webinar, I gave a general description of capacitance. Then, I gave an explaination of how capacitance relates to the electromechancial performance of an ultrasonic/piezoelectric transducer. I provided many tip for measurement, including how to practically use capacitance measurements for important analysis.

Here is the outline of the webinar.

0:16 - Outline
1:20 - Blurb about my consulting work
2:39 - Detailed outline
4:00 - What is capacitance?
6:51 - Capacitance with AC voltage
10:20 - How do you measure capacitance?
12:56 - What frequency to use for measuring capacitance?
16:56 - Electromechanical analysis of capacitance for piezoelectric transducers
29:40 - Misc. expert tips to measure capacitance
32:46 - Several ways to use capacitance measurements

*** Announcement ***

My next webinar will be December 9, 11AM ET " Relationship between voltage, current, power, and displacement in an ultrasonic transduce [Topic may change based on feedback]"

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

Parameters to measure in ultrasonic transducer impedance analysis

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 11 Oct 2022 15:28:22 GMT

I hosted a webinar on October 7, 2022 on

" Parameters to measure in ultrasonic transducer impedance analysis "

You can watch the recording on my YouTube Channel here:

https://youtu.be/4qUYmYwpCBQ

Here is a link to the presentation notes: Lin k

Topics

In this webinar, I give a comprehensive overview of piezoelectric and ultrasonic transducers. Here are the topics:

0:59 - Outline
2:00 - About Ultrasonic Advisors
2:59 - What is impedance?
5:21 - How is impedance measured?
7:40 - Measurement of an ultrasonic cleaning transducer
20:00 - Measurement of Q-factor from impedance
24:50 - Measurement of Q-factor from conductance or real admittance
26:56 - Explanation of real impedance and admittance parameters
30:50 - Impedance measurement of piezo-unimorph
34:00 - Describing poor measurement when transducer is left on table
34:50 - Utilizing conductance and resistance to describe response of piezo-unimorph with great representation
37:10 - Calculation of Q-factor from conductance
41:40 - Measuring Q-factor accurately in the present of large damping on piezo unimorph

*** Announcement ***

My next webinar will be November 4, 11AM ET " Electrical analysis of Ultrasonic transducers - Capacitance [Topic may change based on feedback]"

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

A comprehensive introduction to piezoelectric and ultrasonic transducers

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 06 Sep 2022 13:00:02 GMT

I hosted a webinar on September 2, 2022 on

" A comprehensive introduction to piezoelectric and ultrasonic transducers "

You can watch the recording on my YouTube Channel here:

https://youtu.be/G1cmEF_4hIs

Here is a link to the presentation notes: Link

Topics

In this webinar, I give a comprehensive overview of piezoelectric and ultrasonic transducers. Here are the topics:

0) Introduction to the topic [2:00]
1) About Ultrasonic Advisors [6:46]
2) Comparison between piezo and condenser microphone [13:11]
3) Origin of piezoelectricity [15:06]
4) Comparison between piezo and traditional speaker [20:50]
5) Survey of different devices [26:13]

*** Announcement ***

My next webinar will be October 7, 11AM ET " Understanding the ultrasonic impedance response"

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

An ultrasonic drive circuit you will understand and can build - a guide for non-electrical engineers

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 01 Aug 2022 13:00:17 GMT

I hosted a webinar on July 29, 2022 on

" An ultrasonic drive circuit you will understand and can build - a guide for non-electrical engineers "

You can watch the recording on my YouTube Channel here:

https://youtu.be/sALJhFkSIoY

Here is a link to the presentation notes: Link

Topics

In this webinar, I covered the most basic circuit that can be used to drive an ultrasonic transducer. I made this video specifically for non-electrical engineers because I boil down concepts to core ideas and only use 2 circuit components to build the circuits.

Here are the topics:

5:30 -What a circuit needs to provide a transducers to be driven
16:00 -Theory of the super simple circuit
31:00 -Construction of the super simple circuit
39:40 -Experimental results of the super simple circuit

*** Announcement ***

My next webinar will be Friday, Sept 2 " A comprehensive introduction to piezoelectric and ultrasonic transducers" at 11AM ET.

Here is the link to sign up for the upcoming webinar: https://www.ultrasonicadvisors.com/monthly-ultrasonic-webinar

How to model piezo ceramic properties in FEA simulations

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 20 Jun 2022 19:45:23 GMT

I hosted a webinar on June 17, 2022 on

" How to model piezo ceramic properties in FEA simulations "

You can watch the recording on my YouTube Channel here:

https://youtu.be/d-JSK1KpaZ8

Here is a link to the presentation notes: Link

Topics

In this video (webinar recording), I use a reference dataset and experimental data measured from a piezo ceramic ring to determine all the tensor piezo properties for the experimental sample.

***Do you have this problem? Then watch the video***

You would like to model your piezoelectric ceramic you will use for prototyping but…

(1) You are ordering ceramics from a supplier that does not provide the entire datasheet

(2) You notice that the ceramics you receive have different properties from the datasheet

*** Announcement ***

My next webinar will be Friday, July 29 at 11AM ET. The topic will be: To be announced (It might be about driving ultrasonic transducers)

Here is the link to sign up for the upcoming webinar: Link

Comparison of Vibration Measurement Systems for Ultrasonic Transducers

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 17 May 2022 14:34:59 GMT

I hosted a webinar on May 13, 2022 on

" Comparison of commercially available methods to measure ultrasonic transducer displacement "

You can watch the recording on my YouTube Channel here: https://youtu.be/_fcbFFGCGV4

Here is a link to the presentation notes: Link

Topics

•Why measure vibration?

•What parameters are important for vibration measurement systems?

•Comparisons between measurement systems

•Visual, light displacement, laser doppler vibrometer

•Analog, digital, cost

•My verdict

*** Announcement ***

My next webinar will be Friday, June 17 at 11ET. The topic will be: How to match FEA and experiments for ultrasonic transducer analysis

Here is the link to sign up for that webinar: https://us06web.zoom.us/meeting/register/tZUld-2srT8oE9weQnqySjtTz8TrhME6Xf1Q

Ultrasonic Transducer Simulation Consultant

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 03 May 2022 17:31:31 GMT

In this video, I introduce my ultrasonic transducer simulation services. (Link to video: https://youtu.be/78PCAv8RArg )

Don't waste time prototyping your transducer designs - follow a modern product development approach by utilizing simulation.

Simulations will accelerate your transducer engineering project. Book a discovery call today to discuss how I can help your project.

Get an ultrasonic transducer expert to do your ultrasonic transducer FEA simulations.

Learn more about getting my help on your project by visiting my website. https://www.ultrasonicadvisors.com/

Webinar Announcement: Ultrasonic transducer displacement measurement methods

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 27 Apr 2022 19:44:30 GMT

I am hosting a 1-hour webinar on

*** Comparison of commercially available methods to measure ultrasonic transducer displacement ***

on Friday, May 13 at 11AM ET.

Here is the link to register

I will share the pros and cons of different displacement/vibration measurement methods including: laser doppler vibrometer, light displacement, visual displacement, and analog vs. digital data acquisition.

How to simulate and analyze ultrasonic transducers using modal analysis like an expert

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 19 Apr 2022 19:58:20 GMT

I hosted a webinar on April 15, 2022 on

"How to Simulate and Analyze Ultrasonic Transducers like an Expert"

You can watch the recording on my YouTube Channel here: https://youtu.be/nVRh-4XeJ8E

Here is a link to the presentation notes: Link

Here is a link to the spreadsheets for calculations: Link

Also, I want to know what topic you want me to present on next month. Vote here on my LinkedIn Poll: Link to poll

My next webinar will be Friday, May 13 at 10ET. I will send the registration link once I decide on the topic from your feedback.

Webinar Announcement: Simulation of bolt-clamped ultrasonic transducers using modal analysis

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 07 Apr 2022 20:06:21 GMT

I am hosting a 1-hour webinar on

***�� ***

on Friday, April 15 at 10AM ET.

Here is the link to register

I will share the methods for design, analysis, and optimization for bolt-clamped ultrasonic transducers.

Some of the methods I will describe can be found no where else.

Piezo SHOCK Show #61: How do you use a long-range microscope to measure ultrasonic displacement?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 11 Feb 2022 22:12:44 GMT

Welcome to the Piezo SHOCK Show #61. In this video, I go through a practical step by step demonstration of taking ultrasonic transducer displacement measurements using a long-range microscope. I also give a rundown of the camera I use.

Watch the episode here: https://youtu.be/7OS0lOpGnr8

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #60: What equipment is needed to visually measure ultrasonic displacement?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 10 Feb 2022 22:09:54 GMT

Welcome to the Piezo SHOCK Show #60. In this video, I describe what equipment is needed to visually measure ultrasonic displacement?

Well, you need a camera, optics, stages, and lighting. Watch the video to learn more about this effective way to measure ultrasonic transducer displacement. The only limitation of this method is that displacements less than 5 microns, in general, cannot be resolved. You also don't get phase information.

Watch the episode here: https://youtu.be/zdPntE-pCT0

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #59: What is the easiest way to determine the polarization orientation of PZT?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 08 Feb 2022 17:44:09 GMT

Welcome to the Piezo SHOCK Show #57. In this video, I show how to measure the polarization of an ultrasonic/piezoelectric element by using heat. This is important in order to attach your piezo elements correctly in your application. Usually, the manufacturer marks a side of the piezo to determine the polarization. This method can be used to double check that or to determine the polarization if the sample is diced.

Watch the episode here: https://youtu.be/F9Q1rFAOyKs

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #58: Should I include pretension and clamping for FEA analysis?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 20 Jan 2022 19:37:42 GMT

Welcome to the Piezo SHOCK Show #58. In this video, I talk about the role of adding pretension and clamping on your ultrasonic transducer in FEA simulation. Basically, don't include them as they provide complexity that has little benefit. I talk about this while taking a leisurely walk. It would be a TRUE pleasure if you can join me.

Watch the episode here: https://youtu.be/_F-Ic116FM4

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #57: Can you automate the measurement of ultrasonic displacement?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 19 Jan 2022 16:58:05 GMT

Welcome to the Piezo SHOCK Show #57. In this video, I show off my measurement tool that I use to automatically extract micron displacement measurement from images of ultrasonic displacement.

The tool is not public yet, but I will release it for free. Please contact me if you are interested in beta testing. Leave a comment or send me an email: husain@ultrasonicadvisors.com

Watch the episode here: https://youtu.be/fShLIwAdaq0

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #56: How can you measure the displacement of an ultrasonic transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 18 Jan 2022 03:44:59 GMT

Welcome to the Piezo SHOCK Show #56. In this video, I used a webcam microscope to measure the micron level displacement of an ultrasonic dental scaler. The first step is to calibrate the camera, getting a micron/pixel value. Then you can take an image of the ultrasonic motion and analyze the spread of a dot reflection. This spread can be measured to determine the displacement. In the video, I showed a displacement of 40 microns.

Watch the episode here: https://youtu.be/OCYojoA0mtQ

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Client Testimonial Video: OVR Technology

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 05 Jan 2022 13:00:11 GMT

Matt Flego, CTO of OVR Technology, describes his experiences working with Ultrasonic Advisors to SCALE the manufacturing operations of their novel ultrasonic atomizer. Their transducer is used to disperse a precise amount of scent for virtual reality devices, providing a completely immersive experience.

"Fundamentally, we really needed to understand the characteristics electrical and physical better. I don’t have a background in piezoelectronics or electrical engineering. Ultrasonic advisors has been a fantastic resource."
"From a need standpoint, we had to quickly scale up into manufacturing, and we had already come up with a design. The process of characterizing out actuator really helped us to perfect its design and manufacturing process."
"The services that you are offering really worked well for us because our manufacturing is scaling very rapidly. This means we have things that come up all of the time, and we really need to bounce deep questions off of you, and that experience has been really good."

Contact me TODAY if you want to be confident in scaling your transducer manufacturing operations.

Link to OVR's website:

https://ovrtechnology.com/

Watch the testimonial video here: https://youtu.be/xV4TCwFvkOs

Learn more about my paid consulting services and a free discovery call here: LINK

Piezo SHOCK Show #55: Does an ultrasonic dental transducer degrade with increasing power?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 04 Jan 2022 12:45:03 GMT

Welcome to the Piezo SHOCK Show #55. According to the measurement of power from low power all the way up to 10W (10x the rated power), the impedance of the transducer does not increase significantly, This is a bit SURPRISING.

Watch this video to see how I conducted the experiment to show this.

Watch the episode here: https://youtu.be/K4Ybkn59cSM

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #54: What is the driver circuit of an ultrasonic dental transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 29 Dec 2021 13:00:02 GMT

Welcome to the Piezo SHOCK Show #54. What is the driver circuit of an ultrasonic dental transducer? It is a push-pull converter circuit. It uses two NMOS FETs and a DC source and a center tapped transformer. Learn MORE and and WATCH this video.

Watch the episode here: https://youtu.be/3ezoGc-bOQ4

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #53: What are the driving voltage levels of an ultrasonic dental transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 27 Dec 2021 15:55:07 GMT

Welcome to the Piezo SHOCK Show #53. In this video, I examine the driving signal which is used to drive an ultrasonic dental transducer. The driving signal is a sorta square wave. At the lowest setting, 40VRMS is applied and at the highest setting ~120VRMS is applied. The maximum power output is 1000mW. This makes sense, as the transducer had a high resonance impedance as seen in the last video (above 1000Ohm at low power).

Watch the episode here: https://youtu.be/N-4hKddA7yU

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #52: Can damping improve the characterization of an ultrasonic dental transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 22 Dec 2021 22:36:29 GMT

Welcome to the Piezo SHOCK Show #52. In some cases, damping helps to clean of the impedance response of an ultrasonic transducer such that a distinct resonance frequency can be identified. This is because damping can remove spurious mode appearances. Watch this video to see if the multiple modes generated in an ultrasonic dental transducer are cleaned up when the tip is submerged in water.

Watch the episode here: https://youtu.be/y-3imT2kKIg

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #51: How to determine Q of an ultrasonic dental transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 21 Dec 2021 21:21:41 GMT

Welcome to the Piezo SHOCK Show #50. In the last video, I introduced the unique method of how a inexpensive transducer was held. In this video, I show the impact the holding method has on the Q of the transducer. The future is NOW.

Watch the episode here: https://youtu.be/6leasN9ZP2M

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #50: How does holding affect Q of an ultrasonic dental transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 17 Dec 2021 15:23:58 GMT

Watch the episode here: https://youtu.be/u05d9FmFgxw

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #49: How is an Ultrasonic Dental Transducer held?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 13 Dec 2021 20:59:36 GMT

Welcome to the Piezo SHOCK Show #49. You can learn so much analyzing inexpensive transducers. In this video, I examine the holding method for an inexpensive ultrasonic dental scaling transducer. Wanna learn more? WATCH this video. Live life with no regrets.

Watch the episode here: https://youtu.be/q_oR5ilYmw0

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #48: What is the difference between clamping and damping for a transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 26 Nov 2021 15:14:54 GMT

Welcome to the Piezo SHOCK Show #48. What is the difference for ultrasonic transducers between clamping and damping? They are actually different things, so let's dive in in this episode! Let me know if you have comments or questions!

Watch the episode here: https://youtu.be/cuzbzyN3Noc

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #47: How does clamping affect a piezo transducer’s response?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 16 Nov 2021 22:20:44 GMT

Welcome to the Piezo SHOCK Show #47. Ultrasonic transducer need to be attached to other structures in order to support, hold, and protect them. The manner and method in which you do this affects the transducers response. In this video, I explore concepts of damping and clamping with a piezo buzzer operated in bending and planar resonances. CLAMP me but don't DAMP me!

Watch the episode here: https://youtu.be/pkz_mrbMJsM

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #46: Productivity for Transducer Engineers - INTERVIEW with Coach Carol Williams

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 09 Nov 2021 13:39:58 GMT

Welcome to the Piezo SHOCK Show #46. This episode is ALL about workplace productivity for ultrasonic transducer engineers. These folks (likely one of you) include startup founders, inhouse engineering staff, and academics.

Transducer engineers seem to have a work overload based on the number of their job requirements. In this episode, I interview productivity guru Coach Carol Williams to help me answer several challenges that transducer engineers encounter regarding workplace productivity. We deal with "soft" topics like organization, risk-taking, as well as speaking about other challenges engineers have with productivity.

Here are the discussion topics by timestamps. (You will need to go to the video directly on YouTube to utilize them: https://youtu.be/bMgVPWjmsWs )

Productivity Challenges for Ultrasonic Transducer Engineers

[0:00] Episode introduction

[1:15] Introduction to Coach Carol, Productivity Guru

[2:28] Disorganization and productivity

[5:00] Scope-creep and productivity

[10:00] Work overload and productivity

[21:16] You should be doing that, but why don't you?

[24:20] Big picture thinking and productivity

[31:13] Finding your strengths

[34:10] Risk taking and productivity

[37:55] Reflection on my work with Coach Carol

To learn more about how Coach Carol can help your productivity visit the following links:

Email: carol@eps-time.com

Her website: https://eps-time.com/

Her free productivity success framework e-book: https://eps-time.com/your-productivity-success-cake.html

Book a discovery call with her: https://eps-time.coachesconsole.com/calendar/available40

Watch the episode here: https://youtu.be/bMgVPWjmsWs

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #45: Can a piezo buzzer be used as a transformer?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 02 Nov 2021 17:18:28 GMT

Welcome to the Piezo SHOCK Show #45. Now, the last thing you think of when talking about a piezo buzzer is an amplifier or a transformer. But, in this video, that's all I'll be talking about. Ultrasonic devices with three unique terminals have the ability to be used as step-up or step-down transformers. I demonstrate this using a three terminal piezo buzzer. OMG!!! A video making a BUZZER into a TRANSFORMER!! A MUST WATCH!!!

Watch the episode here: https://youtu.be/JL4szD4GWjU

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #44: How can you measure the Q-factor from a microphone?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 29 Oct 2021 12:46:25 GMT

Welcome to the Piezo SHOCK Show #44. Q-factor is not just an electrical parameter! It is also a fundamental material property of elastic materials. In this video, I explain how to calculate Q factor of a metal dinner fork using a microphone and an audio recording software (Audacity). This video is really EYE-OPENING for engineers only used to seeing Q-factor as an electrically measured parameter.

Watch the episode here: https://youtu.be/bv5neb2n2oM

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #43: How To Talk To Piezo Ceramic Suppliers?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 22 Oct 2021 14:19:09 GMT

Welcome to the Piezo SHOCK Show #43. In any ultrasonic transducer project, your supplier of your ceramic plays a critical role in achieving your product's success. In this episode, I speak about the differences between Asian and American/European piezo suppliers. Additionally, I speak about how to determine mechanical and electromechancial tolerances for your ceramics, which is a must-have when you order your ceramics for use in a late stage prototype or final product. Get SPEC'd out and WATCH this video.

Watch the episode here: https://youtu.be/f4ZoHHfz5_Q

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #42: Interview with Asian Piezo Supplier Liaison, Jack Gray

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 19 Oct 2021 15:58:44 GMT

Welcome to the Piezo SHOCK Show #42. In this episode of the Piezo Shock Show, I interview Jack Gray of Piezo by Graco . His company provides services as a liaison to Asian piezoelectric ceramic and transducer suppliers. The audio is a little hard to hear near the beginning but listen closely and you will get PURE GEMS with regards to sourcing your next piezo ceramic and transducer

Watch the episode here: https://youtu.be/c8tDQMqEQCU

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #41: How can you remember the different types of PZT?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 13 Oct 2021 19:48:02 GMT

Welcome to the Piezo SHOCK Show #41. I have to admit, it is not easy for me to remember the different industry naming schemes for PZT. In this video, I go over the different types of PZT as well as my method for remembering the naming scheme that is commonly used in industry. Enjoy this episode of the Piezo SHOCK Show.

Watch the episode here: https://youtu.be/c8tDQMqEQCU

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #40: How to measure the coupling factor with modal analysis?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 11 Oct 2021 17:01:57 GMT

Welcome to the Piezo SHOCK Show #40. Being a piezo expert has its perks. One of them is having the ability to use "lesser" tools to create brilliant results. In this video, I share a tactic of mine which turns mundane modal analysis into a piezo analysis powerhouse via calculation of the coupling factor. If you like this video, PLEASE give a donation to your favorite ultrasonic transducer expert.

Watch the episode here: https://youtu.be/aDMs7sdlWwM

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #39: How to measure piezo ceramic variability easily?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 07 Oct 2021 16:01:52 GMT

Welcome to the Piezo SHOCK Show #39. Yes, piezo ceramic measurements can be complex, but that should not scare you into doing nothing. In this video, I give a practical tip to give you entry into piezo measurements by means of capacitance measurement. This is a powerful step toward quality control of your ceramics. Take CONTROL of your transducer manufacturing quality and WATCH this video.

Watch the episode here: https://youtu.be/FRYRW6KupeM

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #38: What happens when you radially pole a piezo crystal ring?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 05 Oct 2021 15:27:30 GMT

Welcome to the Piezo SHOCK Show #38. In this video, I describe what happens when you radially pole a piezo ring. This is a unique case as we typically pole in a uniform direction, so we can learn a lot from the behavior of such a ring. I hope you enjoy the video

[Sorry for the poor audio and visual quality. None the less, listen with your ears and you will get a lot from the content still. I strongly encourage looking at the notes and listening to the video]

Watch the episode here: https://youtu.be/jbEXl0n6ElI

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #37: Should an ultrasonic transmitter and receiver be used in phase?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 01 Oct 2021 19:54:50 GMT

Welcome to the Piezo SHOCK Show #37. The transmitter receiver applications of ultrasonic transducers are quite different than many power ultrasonic transducer applications. Firstly, there is a loosely coupled medium (air or water). Then, there is a lack of global resonance, although there is local resonances. Watch this video to learn about transmitter receiver operation and signals. I think this VIDEO is SOOO cool because it helps us POWER ultrasonic folks think in a new dimension.

Watch the episode here: https://youtu.be/zsnsonXnlvU

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #36: Can you use cheap equipment to measure ultrasonic transducer impedance?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 29 Sep 2021 18:05:10 GMT

Welcome to the Piezo SHOCK Show #36. Does cheap mean bad quality? There is some truth in this, but in the case of impedance measurement of ultrasonic transducer there quite a many options. Watch this video before making a purchase of an impedance analyzer. Your wallet will thank me. Watch this EPISODE!

Watch the episode here: https://youtu.be/EU0E3bUilb4

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #35: Should I use a square or sine drive for my ultrasonic transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 28 Sep 2021 16:07:25 GMT

Welcome to the Piezo SHOCK Show #35. There are two main types of waveforms used to drive ultrasonic transducers. The good kind and the bad kind... Okay, not really. The two types are square and sine waves. Basic rule of thumb, use sine waves unless you constrained by circuit simplicity and cost. Watch this episode and LEARN the what you need to know about SINE and SQUARE wave drive.

Watch the episode here: https://youtu.be/YDQwkWBjVQU

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #34: Should I use an oscillator circuit to drive my ultrasonic transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 25 Sep 2021 20:28:43 GMT

Welcome to the Piezo SHOCK Show #34. Oscillator circuits were the first circuits used to drive ultrasonic transducers. They don't require digital control and are quite capable at handling high frequencies. In some cases they are self-tuning, but that aspect does provide challenges to their stability. Learn more about using oscillator drive circuit in your next ultrasonic transducer project and watch this video.

Watch the episode here: https://youtu.be/zG94bkflt2A

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #33: How can we drive an ultrasonic transducer with a bridge driver?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 24 Sep 2021 13:27:33 GMT

Welcome to the Piezo SHOCK Show #33. Bridge driver circuits are a great, simple, and inexpensive way to drive ultrasonic transducers. They are can work at high frequencies. In this video, I describe how three types of bridge drivers can be used to drive ultrasonic transducers. This video will arm you with a high level understanding of topic.

I GUARANTEE you will be oscillating out of your chair after watching this video

Watch the episode here: https://youtu.be/p2_l8SvhbgQ

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #32: Let's talk about ultrasonic transducer driver topologies and power op amps!

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 22 Sep 2021 21:23:14 GMT

Welcome to the Piezo SHOCK Show #32. Without voltage and current, your transducer is nothing more than an expensive paper weight. In this video, I talk give background info about ultrasonic driver topologies, and get into some of the specifics of power op amp drivers. This high level description is a MUST watch for those starting work in designing transducer driving circuit. Enjoy the video!

Watch the episode here: https://youtu.be/XuFXUaXLDX0

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #31: How is electrical power and oscillation related for an ultrasonic transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 21 Sep 2021 15:10:06 GMT

Welcome to the Piezo SHOCK Show #31. This video is a mini finale on some of my higher level discussion of voltage, current, power, and mechanical oscillation. In this video, I tie to bow on the discussion of power in how it relates to mechanical oscillation. I use an example of an ultrasonic cutting transducer operating at resonance to exemplify my point. Enjoy the video!

Watch the episode here: https://youtu.be/eRzGnOoBk0k

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #30: What is the ultrasonic transducer "W" curve?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 21 Sep 2021 00:46:36 GMT

Welcome to the Piezo SHOCK Show #30. This episode is GOLD. I talk about the ultrasonic "W", which is a name I created for the response of voltage and current if a constant power frequency sweep is carried out over a piezoelectric transducer. I also explain the constant of voltage controlled oscillation at antiresonance and current controlled oscillation at resonance.

People, this is as close to printing money as I am going to get.

Watch the episode here: https://youtu.be/a8POR6l8GHc

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #29: What is special about resonance and antiresonance for a drive circuit?

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 18 Sep 2021 21:17:20 GMT

Welcome to the Piezo SHOCK Show #29. There are so many reasons why resonance in ultrasonic transducers is awesome. The reason I speak about in this video is that they provide a purely resistive load to your drive circuit, thereby allowing the drive circuit to efficiently drive it. Otherwise, you'd be stuck providing more current and voltage for the same displacement, even if the power dissipated from the transducer is the same.

Watch this video and be DAZZLED.

Watch the episode here: https://youtu.be/n_Hf0J3pXWc

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #28: How can you use current for self-sensing in an off-resonance piezo actuator?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 17 Sep 2021 20:47:55 GMT

Welcome to the Piezo SHOCK Show #28. Piezoelectric transducers are amazing, not just cause I work on them, but they truly are. In this video, I talk about a piezo actuator's ability to do self-sensing. You can actually calculate the velocity and displacement of a piezo actuator by measuring the current, which is quite easy to do. Enjoy the episode.

Watch the episode here: https://youtu.be/mQvao_ezhHc

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #27: What are the ways to determine the resonance frequency?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 16 Sep 2021 18:13:20 GMT

Welcome to the Piezo SHOCK Show #27. I one hundred percent believe the best way to understand something is the get hands on - that includes the understanding the resonance frequency. In this video, I go over a few way to measure the resonance frequency of ultrasonic transducers which can be completed with readily available electronic measurement equipment.

Watch the episode here: https://youtu.be/BpDsVDfjRhg

Learn more about my paid consulting services and a free discovery call here: LINK

Here are some additional video with lab demonstrations:

Impulse measurement of the resonance frequency: https://www.youtube.com/watch?v=4oTPUUKjoYM&ab_channel=LearnPiezo
Measuring resonance from a function generator and oscilloscope: https://www.youtube.com/watch?v=HyuhtnQiOx4&ab_channel=LearnPiezo

I've posted the video notes below:

Piezo SHOCK Show #26: Why is the piezoelectric charge constant d31 a negative number?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 15 Sep 2021 19:55:10 GMT

Welcome to the Piezo SHOCK Show #26. d31 is a negative number. Why? and more importantly, why should you care? You should care because you can learn and understand a lot of what happens in a piezo from understanding why d31 is negative. In this episode, I explain not only why d31 is negative, but recap many important basics of piezoelectric material properties.

Demystify your understanding of the piezoelectric charge constant and click the link and watch the video - you will thank me!

Watch the episode here: https://youtu.be/9X7TsNrFk_I

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #25: What is the other reason why we love the resonance frequency?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 14 Sep 2021 15:23:15 GMT

Welcome to the Piezo SHOCK Show #25. Of course! If you have been watching my videos, you already know that the resonance frequency of an ultrasonic transducer provides the maximum mechanical oscillation for a given drive voltage. But is that the only reason why we love the resonance frequency? In this episode, I explain why mode shapes are the second reason we love resonance. Click the link and watch the video - this is solid content, for real.

Watch the episode here: https://youtu.be/kmEiQ1P09Zs

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #24: Why do ultrasonic transducers have a preload?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 13 Sep 2021 13:19:54 GMT

Welcome to the Piezo SHOCK Show #24. One of the main focus points in designing and assembling ultrasonic transducer has to do with preload. But why is preload important? In this episode, I explain three reasons why preload is an important parameter to understand and optimize. Click the link and watch the video - this is solid content bro.

Watch the episode here: https://youtu.be/Q_tATird0QQ

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #23: What is the importance of wavelength for the design of ultrasonic transducers?

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 12 Sep 2021 18:27:17 GMT

Welcome to the Piezo SHOCK Show #23. Everything about designing ultrasonic transducers is about the wavelength of sound. The wavelength changes based on frequency, which is why higher frequency devices are smaller. Watch this video to learn more about design of an ultrasonic transducer based on wavelengths.

Watch the episode here: https://youtu.be/OY34d7bjthg

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #22: Can ultrasonics work in energy storage, power transfer, and energy harvesting?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 10 Sep 2021 17:26:19 GMT

Welcome to the Piezo SHOCK Show #22. Piezoelectric materials and their applications in ultrasonic transducers are amazing. That being said, this has caused undo interest in their use in other applications, particularly in power related applications. In this video, I break down how I view the role of piezoelectric materials and ultrasonics in energy storage, power transfer, and energy harvesting.

Watch the episode here: https://youtu.be/_8A4mMhlfRM

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #21: How to interpret the specifications of an ultrasonic transducer amplifier?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 09 Sep 2021 17:59:49 GMT

Welcome to the Piezo SHOCK Show #21. There are many parameters that you need to pay close attention to when shopping around for an laboratory bench amplifier for your ultrasonic transducer development project. In this video, I go through the specifications of voltage, current, slew rate, gain, power bandwidth, signal bandwidth, power, and distortion for a commercially available amplifier.

Here is a link to the spec sheet I went over in the video: https://www.mmech.com/piezodrive-amplifiers/px200

Watch the episode here: https://youtu.be/nwjGa8vFiMQ

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #20: How do you measure the blocking force of a piezoelectric actuator?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 08 Sep 2021 17:06:06 GMT

Welcome to the Piezo SHOCK Show #20. There are two parameters that fully describe a piezoelectric actuator - those parameters are blocking force and free displacement. Free displacement is rather easy to measure. Blocking force measurements, on the other hand, requires careful fixturing. In this video, I describe the general approach of how to measure blocking force as well as some details around multilayer actuator measurements.

Watch the episode here: https://youtu.be/FdLZxzp3hw8

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #19: How do you measure the operating power of an ultrasonic transducer?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 07 Sep 2021 18:14:09 GMT

Welcome to the Piezo SHOCK Show #19. Power dissipation is a fundamental measurement of ultrasonic transducers. The voltage and current measurements don't always speak well to the amount of mechanical excitation, but power dissipation always describes the amount of mechanical movement well. In this video, I speak about some of the theory behind power dissipation measurement as well as how to measure it.

Watch the episode here: https://youtu.be/e20xESQrNP8

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #18: How can you interpret an ultrasonic transducer datasheet?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 06 Sep 2021 19:24:43 GMT

Welcome to the Piezo SHOCK Show #18. Piezoelectric/Ultrasonic transducers come with a variety of specs which can be obtained from their datasheet. The specs typically are geometrical size, resonance frequency, capacitance, power, quality factor, and resonance impedance. In this video, I go over a specific transducer datasheet and discuss how the parameters relate to the particular transducer.

Here is a link to the datasheet: https://api.kemet.com/component-edge/download/specsheet/NBL45402H-A.pdf

Watch the episode here: https://youtu.be/L7ZK8pIZF3k

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #17: How does a piezoelectric transformer work?

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 05 Sep 2021 16:42:44 GMT

Welcome to the Piezo SHOCK Show #17. Piezoelectric transformers are cool - they convert electrical signals to mechanical strain and back to electrical signals. They are utilized for both step up and step down applications. They really outshine EM transformers in applications where small size is a big deal. Watch the video to learn more!

Watch the episode here: https://youtu.be/VQ1kcqOsATM

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #16: How can you calculate the voltage generated on a piezo bender with FEA?

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 04 Sep 2021 20:21:58 GMT

Welcome to the Piezo SHOCK Show #16. Piezo benders work quite well for generating decent voltages from small forces. In this video, I describe how to calculate voltage on a piezo from bending stresses calculated from FEA, specifically a Fusion 360 simulation. In the example, 81 volts were generated from 10 N of force.

Watch the episode here: https://youtu.be/5_rMhCQYPE4

Learn more about my paid consulting services and a free discovery call here: LINK

I've posted the video notes below:

Piezo SHOCK Show #15: What can power ultrasonics folks learn from surface acoustic wave devices?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 02 Sep 2021 19:40:46 GMT

Welcome to the Piezo SHOCK Show #15. To people normally working in power ultrasonics, where devices either have bending (transverse) or longitudinal (bulk acoustic) resonating operation, surface acoustic waves are quite strange.

In this video, I explain some of the nuances of such devices. You can better understand power ultrasonic devices by understanding the differences between surface acoustic waves and traditional transducers.

Watch the episode here: https://youtu.be/_OH_wAvSB-c

I've posted the video notes below:

Piezo SHOCK Show #14: How does a transducer behave differently in an array vs. alone?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 01 Sep 2021 21:15:16 GMT

Welcome to the Piezo SHOCK Show #14. Many applications use piezoelectric transducers in an array vs. alone. Although the devices are electrically in parallel, they still have mechanical interaction which can INCREASE the overall efficiency of the devices. Watch this video to find out how!

I utilize piezoelectric buzzers which when placed close together, have acoustic coupling.

Watch the episode here: https://youtu.be/MSFkJQaHsOY

I've posted the video notes below:

Piezo SHOCK Show #13: How do I determine mode type in a low aspect ratio ceramic sample?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 31 Aug 2021 15:45:27 GMT

Welcome to the Piezo SHOCK Show #13. In this episode, I explain how to determine the type of mode you are measuring using frequency constants. It turns out, the aspect ratio of the low aspect ratio sample was not low enough to prohibit the use of frequency constants to determine the mode type. However, I would caution it's use for reporting material properties.

Watch the episode here: https://youtu.be/hOg34_zpzfU

I've posted the video notes below:

Piezo SHOCK Show #12: How do I interpret the second mode of a planar/radial resonator?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 30 Aug 2021 15:59:15 GMT

Welcome to the Piezo SHOCK Show #12. In this episode, I discuss the awesomeness that is planar resonators. Planar resonators take the cake in terms of being great all round material samples for property characterization. The third harmonic (second appearing mode) of a radial resonance provides vital data needed to resolve the elastic material properties.

Watch the episode here: https://youtu.be/R9b7JuwJVNk

I posted some of the visual notes below:

Piezo SHOCK Show #11: How can I measure variability between transducer from different manufacturers?

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 29 Aug 2021 17:02:30 GMT

Welcome to The SHOCK Show #11. In this episode, I will answer the question: "Do transducers between manufacturers have a lot of variation and how can I measure it ?"

Read on or watch the episode here: https://youtu.be/EI0XlicSO48

Variability in ultrasonic transducers between manufacturers

There are 4 areas where variability creeps into a transducer production operation. They are (1) Piezo ceramic property variability (2) Assembly process and tolerance variability (3) Variability in properties of the elastic materials and (4) Variability in behavior of wires, cabling, and connectors.

(1) Piezo ceramic property variability

Most transducer manufacturers that have been around long enough have almost certainly encountered significant variability issues due to piezo ceramic property variability. A swing in properties up to 30% is not hard to believe. If you have not already, subscribe to my blog and receive my guide to the top three challenges in ultrasonic transducer development. Link to subscribe is here: ultrasonicadvisors.com/blog-home

(2) Assembly process and tolerance variability

Interfaces and component build up plays a huge role in determining losses, resonance frequencies, stability of the transducer over time, and spurious behavior. In the life of a product, non-experts can make improvement decisions which inadvertently impact the consistency of the product. Many ultrasonic transducers are also made "by hand", and thus have an inherent variability between assemblers and between build sites.

(3) Variability in properties of the elastic materials

Elastic materials used in transducer construction are typically the most stable in terms of variability, especially metals, however, their loss properties are sensitive to microstructure, so in an ideal sense their properties should also be monitored. Epoxy is a big wild card in this area. If any problem occurs in your company's transducer, you will never sound dumb if you say the problem might be the epoxy.

(4) Variability in behavior of wires, cabling, and connectors

Finally, cabling, connections, and wires add stray capacitance, inductance, and resistance. This will most certainly mess with your transducer's performance, especially in sensor applications. Controlling the stray electrical behavior of your electrical connections, wires, and cables will ensure consistent performance of your sensor.

You still did not answer the question!

Oh yes, let me get back to the question:

Do transducer between manufacturers, that are apparently supposed to be the same thing, have significant differences?

Yes they can, especially because each manufacturer will be dealing with their own version of the top four reasons for transducer variability that I just described. It is important to note that although manufacturers are using equivalent piezo ceramics for similar applications, no two manufacturers can provide the same exact piezo material. Not only that, but the properties have significant variability at even a single manufacturer.

And the next question:

How can I determine the differences between transducers?

There are both analytical and system level ways to do it. The system level methods involve the final application, which is already familiar to the questioner, so I'll skip that. However, the analytical way to determine transducer differences is the ultizie impedance analyze of the transducer and to compare summary parameters. I have a course on that subject here: ultrasonicadvisors.com/impedance_course

However, the point of this article was not to lead you down a rabbit hole to think the only way you can get practical steps for evaluation is to purchase my $1,350 course.

Here is the power action you can do to easily stay on top of your understanding of the differences of your transducer: measure the capacitance

The capacitance of an ultrasonic transducer indicates toward the electromechanical coupling of the device. It is the most dead simple way to understand transducer differences. In most cases, you can apply the golden rule

Piezo Shock Show #10: How does the loss factor affect generated voltage on a piezo?

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 28 Aug 2021 20:14:39 GMT

Welcome to The SHOCK Show #10. In this episode, I will discuss the effects of the loss factor on the generated voltage of a piezo due to an applied force.

I will talk about both off-resonance (semi-static/static) and resonance applications.

Read on or watch the episode here: https://youtu.be/XVLY2RFrWpI

The link between losses and piezo properties

Due to material microstructure phenomenon, larger piezoelectric constants in terms of the piezoelectric charge constant and the permittivity will always be accompanied with larger losses. This is because the phenomenon (domain wall motion) responsible for increasing the properties also increases irreversible energy transfer appearing as losses.

The apparent property, the real property, and the "loss" property

Describing losses opens up a new can of worms for the mathematical description of losses. The apparent material property is actually a complex number. So, for example, if you charged up a piezo, you will not be able to recover all of the energy by charging back down. The difference, also known as hysteresis losses, will represent the lost energy and the recoverable energy is known as the true stored energy.

So, in order to describe the apparent property, we can either use complex number notation where the stored energy property is the "real" component and the loss property is the "imaginary" component. However, typically, we take the magnitude of the complex value ( like this: sqrt(A^2+B^2)) and the phase angle between the real and imaginary value to find the "loss factor". It's a fact of nature (and math) that the loss factor also is the exact same thing as the phase angle between input and output values (eg voltage and charge). Typically, because the loss factor is small, the apparent property is very close to the real property.

An example to answer the question

So, what if we had two material with the same apparent material properties (piezo charge coefficient, compliance, and permittivity) but one had 10x the losses of the other, what would be the difference in the voltage generated in:

Static or low frequency
Resonance

Static Case

In the static condition, the difference between the two material is very small. Even if losses of tan delta = 2% were given to the high loss material, the apparent material properties would change very little.

However, there would be a difference. A more lossy material would appear slightly stiffer than a low loss material, assuming their "real" properties were the same. Therefore, the strain would be lower for the high loss material and thus the voltage would be slightly lower.

All this being said, losses play a small role in static operation of devices, so typically the benefits of high piezo constants far outweigh the disadvantage of high losses.

Resonance Case

This one is gonna be obvious. The resonance strain is highly affected by the loss factors. This is because low losses give a direct amplification to energy stored in the oscillator. So, the material with low losses is going to trump the high loss material with force excitation at the resonance frequency.

Piezo Shock Show #9: Why do piezo benders generate so much voltage?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 27 Aug 2021 14:58:51 GMT

Welcome to The SHOCK Show #9. In this episode, I will give a simple but important demonstration regarding piezo bending transducers. Why does bending generate so much more voltage than axial forces?

The discussion in this episode will focus on off-resonance applications.

Read on or watch the episode here: https://youtu.be/zAVU1niDfd0

Bending is the simple lever of piezoelectric transducers

In comparison to axial loading and longitudinal transducers, piezoelectric benders are predisposed to generate a significant amount of displacement with an applied voltage and a significant amount of voltage for an applied force.

Piezoelectric ceramics, especially PZT, typically generate nanometers of displacement for tens of volts applied. But don't dismiss these nanometers - they are unstoppable. The blocking force of these materials are relatively huge. That being said, many applications, especially low frequency/off-resonance applications, require millimeters of displacement, but less force.

The magic of bending

The magic of bending is that displacement accumulates across the length. by attaching a passible material to a piezoelectric element, the neutral axis is shifted and the axial displacements of a piezo now create a movement and hence bending. Without shifting the neutral axis, a piezo element will never undergo bending under an applied voltage nor see voltage generated when subjected to a moment.

What bending does is shift the high force-low displacement nature of piezoelectric materials in a low force-high displacement function. You can think of it as a permanent change in the transmission of displacement and force, much like shifting gears, only permanently.

On with the demo!

In this demonstration, I've hooked up a piezo buzzer (piezo element bonded to a brass shim). When I apply a light bending force, huge voltage is generated (and also large displacement). When I squeeze axially really hard, only a small voltage is generated.

The only way to effectively couple a transducer to air is to achieve large displacement. This is why bending transducers having large displacement, like a buzzer, are used for sound generation and microphones.

Ultrasonic applications of bending

On example of an air bending transducer is the ultrasonic range finding transducer. It has a unimorph (one piezo layer and one passive layer) bonded to a cone. That being said, you won't be using a bender for welding or other high power applications because benders have low resonance frequencies due to their low stiffness.

I'll end this article with this: Every design topology has its place in the universe.

The SHOCK Show #8: Why Is Piezo Capacitance Is Not Affected By The Sample Holder?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 26 Aug 2021 21:37:45 GMT

Welcome to The SHOCK Show #8. In this episode, I talk about why capacitance measurement of piezoelectric devices, namely crystal resonators, are not affected by the sample holder when measuring capacitance.

At the off-resonance frequencies used to measure capacitance, stiffness dominates the mechanical response of the piezo. Because the sample holder stiffness is small in comparison to that of the piezo, there is little effect on the measurement from the sample holder . The same cannot be said about resonance, where both mass and stiffness affect the response.

Read on or watch the episode here: https://youtu.be/zAVU1niDfd0

The SHOCK Show #7: How Can You Reduce the Variability of Piezoelectric Materials?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 25 Aug 2021 20:20:57 GMT

Welcome to The SHOCK Show #7. In this episode, I talk about variability in piezoelectric material properties and how to reduce them. Inspired from my experience ordering drinks at Starbucks, I describe an effective method for reducing variability and thus increasing yield.

Read on or watch the episode here: https://youtu.be/Tfz28taN46U

Yes, one of the largest problems in piezoelectric transducers are the piezoelectric transducers

Piezoelectric materials of the same type have a VERY significant amount of variability. Some manufacturers cite +/-20% tolerance. Now, there are several ways to ensure that this huge swing in properties will still result in successful minimally varying products. This is the real magic of ultrasonic transducer design, analysis and production

What does piezo variability have to do with Starbucks?

Everything, everything, EVERYTHING! When I go to Starbucks, I often get the Vanilla Sweet Cream Cold Brew. Many times, they put too much cream or too little cream. When I ask for a remake when I get too much cream, my next drink gets too little cream. Same story when I ask for a remake for a drink with too much cream.

Therefore, I get another cup and mix the two drinks together. I am one happy camper with a huge drink just the way I like it!

Okay.. I'll ask again, what does this have to do with Starbucks?

A key way to reduce variability in piezoelectric devices is to pair elements with low electromechanical coupling with those with high mechanical coupling. This reduces the variability significantly, more than half! So, just like mixing two drinks on opposite ends of the "cream-spectrum", you can mix piezo element at opposite ends of the property spectrum. THIS IS A HUGE DEAL!

Read more about piezoelectric material/ceramic property variability in my guide to the top three challenges in ultrasonic transducer development by subscribing to my blog using the form here: ultrasonicadvisors.com/blog-home

If you have already subscribed to my blog, you received this guide when you joined my list.

The SHOCK Show #6: How do I determine full piezo property matrix for FEA?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 24 Aug 2021 14:19:40 GMT

Welcome to The SHOCK Show, Episode #5. So, I've been talking for the last three episodes about what causes non-symmetric resonance impedance and what to do about it. BUT, I didn't talk about why you should even care. Let me convince you that you should care in this episode.

Read on or watch the episode here: https://youtu.be/lhIBTmlEDIQ

What is the correct approach to FEA and experiments?

The whole reason why you want your material properties to be "correct" is to improve the accuracy of prediction of experimental behavior. The trap here is when we start to search for exact agreement, which can be an unending endeavor.

In almost all cases, FEA is best suited for understanding and verifying the function of a particular design rather than predicting precise displacement and impedance responses. This is because there is a lot more things different between experiments and FEA than just the differing piezo material properties from your experiment and simulation

So what's different?

The most drastic differences between experiments and FEA are:

The effects that component interfaces play in loss and stiffness
The unique behavior of high power operation, which results in nonlinearity and losses galore!

Now for the reason you are reading this article: Full piezo property matrix calculation

Everyone is asking me about how to input custom properties into FEA simulations despite not having all of the anisotropic material properties. So here is your desire:

L et's get started!

Firstly, find a full set of material properties from a similar material. For example, if you are using a hard PZT, find a full matrix of material properties of another hard material
Using data sheet values or values that you measure, compare ONE calculated coupling factor (k^2) from your material to the reference material. Find the ratio. Use this golden ratio to back calculate the coupling factors for the k15, k33, and k31 modes.
Create ratios for permittivity and compliance. Then, back calculate all the missing values for your material
Calculate the d15, d33, and d31 using the definition of the coupling factors and their relationship with the piezo charge coefficient, permittivity, and compliance. IE k^2=d^2/(compliance*permittivity) . Solve for d15, d33, and d31
Now we will focus on the quality factor
Measure your quality factor of your material experimentally. Divide this number by 3. If you are using the material data sheet Q-factor, divide it by 5. This will be close to the high power Q-factor
It is much better to measure Q-factor from your assembly and measure Q factor in that way rather than just using crystal level Q-factor. You can then apply the 1/3 factor mentioned in the last bullet point.
I recommend using a single loss factor for your material/assembly. Although piezo ceramics have loss anisotropy, for practical purposes you just need to consider one loss factor.

The SHOCK Show #5: Why Should You Care About Non-symmetric Resonance Impedance?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 23 Aug 2021 12:58:26 GMT

Read on or watch the episode here: https://youtu.be/qw8dyWWBb9w

First things first

Well, firstly, your analysis will be incorrect. Without analytically correct analysis, what essentially you will be doing is analysis of patterns. But, in order to make deep conclusions you have to take that raw data and perform some data conversion based on physics, and then analyze that data.

Here is your pool of sand!

For example, if you have a swimming pool of sand and a few gold grains in it, you will never find it by scooping it with your hand. You could use a sieve, but you are summing you don’t have a lot of rocks.

What you need is a metal detector. Correct use of analytical tools/equation/experimental setups result in a heightened super sense of detection. Without this, your efforts to solve deep issues will just kick up dirt.

Also, non-filtered data is more susceptible to variability, error in measurement going undetected, and underlying patterns going unnoticed, and lack of data cohesion.

The SHOCK Show #4: Why is my resonance impedance not symmetric? Nonlinearity P3

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 22 Aug 2021 23:28:47 GMT

Welcome to The SHOCK Show, Episode #4. Today, I’m going to continue with the third reason why the resonance impedance response of a ultrasonic transducer can be non-symmetric. This reason has everything to do with non-linearity! Finally, we are getting to some juicy stuff.

Read on or watch the episode here: https://youtu.be/NppCKhcthPw

The two effects of nonlinearity

Apparent linear properties become variable and dependent on amplitude of excitation
Additional harmonics are generated

Treat the nonlinear as linear

The definition of linearity is that if you excite a system with a certain frequency, you will get that frequency and only that one back in the response. So, the linear method of describing a nonlinear behavior is by change in citing change in linear properties. That is, for example, change in the d33, compliance, and permittivity with excitation.

Let’s take a look at the implication of this.

Nonlinearity creates non-symmetric resonance impedance

When a piezoelectric transducer oscillates near its resonance frequency, it’s level of oscillation increases until it peaks and them comes back down. Now, note that the properties of your transducer vary depending on the level oscillation.

Let’s analyze compliance, which increases with increased oscillation. As we are doing our frequency sweep, the oscillation increases and thus the compliance starts to increase. This causes the resonance frequency to retreat. The end effect of this is either a sharp dip and then a slow accent or a non-continuity in impedance.

For low voltage measurements, the first type is more common. However, because your impedance analyzer has a finite output impedance, it intrinsically limits the current delivered to your device, thus forcing the oscillation amplitude to remain relatively constant

Triangle waves? Just when you thought the worst was over

The second thing that nonlinearity does is inject additional harmonics, namely 3 ^rd harmonic, into your response. This often results in your final current waveform having a more triangle wave-look than a sine wave. That being said, I have not seen that typical impedance analyzers can drive a transducer to this level of nonlinearity. A triangle wave has a lower RMS value than a sine wave for the same amplitude.

The harmonic solution

In order to do appropriate analysis, the FFT spectrum must be analyzed for first and third harmonics. The first harmonic should be used for impedance characterization, but information regarding average DC power and the amplitude of the third harmonic should be recorded.

Avoiding nonlinearity?

Nonlinearity is part of the ultrasonic transducer game. However, controlling excitation levels and performing FFT help us to come to terms with the peculiarities of nonlinear behavior.

The SHOCK Show #3: Why is my resonance impedance not symmetric? P2

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 21 Aug 2021 21:11:23 GMT

In this episode of the SHOCK show, I am going to discuss why we have nonsymmetric resonance response (impedance). The first reason (covered Episode #2) was that the coupling factor and the quality were lo w. The second reason covered here, still linear, is that multiple resonance modes can coincide.

Read on or watch the episode here: https://youtu.be/qcRxcV0p6Ug

And yes, I'll be talking through a mirror this episode!

Important definition

Also, FYI, the word for non-desirable resonance close to your operating resonance are called SPURIOUS MODES.

What is the deal with these coinciding modes?

There are a few causes for this effect of multiple modes. One of these causes, for a longitudinal transducer is that other modes such as bending modes and component modes can lie close to the operating frequency. This includes a screw/bolt resonance inside the clamped ends of the transducer (screw threads and bolt head). This might cause more than one resonance mode to lie on top of another one. This does depend on the resonance frequency associated with these modes. If the spurious modes lie near the resonance frequency, the resonance response will widen, not allowing you to use equivalent circuit analysis that is reserved for single mode analysis. Not to say that your driver will have trouble picking frequencies and also dump a significant energy into useless oscillation.

Defect free is the way to be... if only that were possible

The other reason modes can coexist at a similar frequency is due to defects. One example of this is imperfect symmetry. For example, if you are bonding a piezo disk to a passive disk and the two disks are not perfectly symmetric, additional closely spaced modes can occur. Epoxy and other interfaces can also have variable properties (bond strength and surface roughness and flatness) – these aspects also result in additional non-desirable resonance modes.

It's not your fault. You were born this way

Before working as a consultant, I thought all spurious modes close to the resonance frequency must be eliminated. That's because I had only worked on longitudal transducers. Bending modes especially are susceptible to spurious modes and many times you actually can't rid of them. At the end of this article, I'll tell you how to live your life in peace despite being surrounded with spurious modes.

Finally, an example!

Let dig into an example with the impedance analysis of a piezo buzzer. Let’s do a frequency response from 3kHz to 5kHz. You can hear the response because it is in the audible range. New Paragraph

So, this transducer has spurious modes, but it doesn’t lie right on top of the resonance at 3.8 kHz. But there are additional modes at 4.3 and 4.5 kHz. These modes will be highly variable as they depend on bond conditions and concentricity.

If these modes landed close the resonance frequency, it would cause a distortion in the response, and typical analysis methods we use will not be valid, such as Q factor determination using the half power bandwidth.

So, are you going to tell me what to do if I have spurious modes or not?

In order to analyze a transducer that has a spurious at resonance, you can fit an equivalent circuit to the antiresonance response and perform analysis from there. Same goes if antiresonance has spurious modes. It’s not possible to determine the effective coupling factor in the presence of strong spurious modes, but it is possible when considering the equivalent circuit for the “pure” response either at resonance or antiresonance.

For most transducers, spurious activity is problematic and should be eliminated both by theoretical design via FEA model analysis. Harmonic analysis does not capture all modes so it has less utility for spurious mode analysis. The second way to eliminate this behavior is to optimize your assembly procedure or iterate different permissible physical dimensions of your transducers. This may help you to come up with a robust design.

If you are stuck with spurious remain calm. You have been given a parachute.

If you are stuck with a transducer with common spurious modes, you will need to supplement your impedance analysis with “ideal” system level analysis. This means measuring responses like displacement vs. frequency or sound pressure level vs frequency. Single point vibration analysis can play a unique role here as the location of the probing site will lead to sensitivity toward certain modes – this can help you to ignore the spurious mode and focus on the important mode of interest.

The Shock Show #2: Why is my resonance impedance not symmetric? P1

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 20 Aug 2021 14:26:43 GMT

Have you ever tried to jam a square in a round hole? Do you say that you are too smart do do that? Well, have you ever applied the 3dB bandwidth to calculate the quality factor of a nonsymmetric resonance impedance response? I think you might have.

In this episode of THE SHOCK SHOW, we will dive into the first reason why resonance impedance is not symmetric. Read on here, or watch the show at the link:

Just because you aren't symmetric doesn't mean you are non-linear

We may jump to conclusions and say our non-symmetric resonance impedance "valley" is not symmetric because of nonlinearity. That can be true, but the reason for asymmetry that I will describe in this episode has nothing do with nonlinearity.

It has everything to do with low electromechanical coupling and low quality factor

If the coupling factor and the the quality factor are low, the parallel capacitor (think the BVD equivalent circuit) has non-negligible impact on the resonance response. A symmetric response, typical of a LCR circuit, shines from the rough when the LCR circuit's response is much larger than the parallel capacitor (coming from the static or intrinsic capacitance of your transducer/crystal.

If the coupling factor is low, than the ratio between capacitances in the BVD circuit is more drastic. AND, if the Q is low, the resonance current in the LCR circuit will also be smaller. As Q and k_eff get smaller and smaller, the response becomes more and more dominated by the parallel capacitor. THIS, causes non symmetric resonance impedance.

So where do we go from here!

Thankfully, because we are still linear despite the asymmetry, we can utilize different approaches for analysis. I go through a universal method of analysis in my impedance analysis course, but here is some information to get you started:

Instead of using absolute impedance for analysis, use real admittance for resonance frequency analysis and real impedance for antiresonance analysis. Q factor in this case is calculated from bandwidth 1/2 the max real admittance.

The Shock Show #1: The two "direct" way to measure the piezoelectric charge coefficient

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 19 Aug 2021 16:50:36 GMT

Welcome to the SHOCK SHOW!

I am starting a everyday live stream event (365 days a year) where I discuss different topics regarding ultrasonic transducer measurement, characterization, and development. Please follow the link to watch the first video on where I discuss:

The two "direct" way to measure the piezoelectric charge coefficient"

Here is the link: https://youtu.be/Y_nZk9_dnas

You can read on here as well!

What is the piezoelectric charge coefficient?

You would be surprised to know how many engineering working on ultrasonic devices cannot explain what the piezoelectric charge coefficient is. It's not their fault. This is not a concept taught in schools and it does not come front and center when doing ultrasonic resonance experiments.

Some engineers think it is a material property that you get when you multiply the coupling factor by the permittivity and compliance. Let's dig into this one.

The direct and the converse piezoelectric charge coefficient

Question: is there a difference in the piezoelectric charge coefficient measured by applying a force and measuring charge (units: Coulombs/Newton) vs applying an electric field and measuring strain (units: Meter/Volt). NO!

C/N = m/V

That's cool! So let's dive into the measurement.

How to measure the charge coefficient, the straight forward way

Yup, I could take you through some hoops on how to measure the charge coefficient using a resonance frequency sweep. However, let me get you straight to the heart of the matter.

Measurement using charge and force (direct effect)

Hook up your piezo material in such a way that you can place a large known force on it. You can even put it between two clamps with a load sensor in series with the piezo. Apply the clamping force. Make sure to measure the voltage with a large parallel capacitor attached, as voltage over a capacitor can be used to measure charge generation. The equation that relates charge per area generated by pressure (force/area) is:

charge/area = force/area *d33

Why don't we use this measurement method instead of a resonance frequency sweep? The charge coefficient has some frequency dependence and requires some cycling to stabilize. Some meters apply a cyclical compressive force on the piezo, but the contact conditions between the piezo and the clamps can be variable, thus increasing measurement error.

Measurement through displacement (converse effect)

When I explain this method to most engineers, they have a "why didn't I think of that moment". The piezo charge constant relates strain (and hence displacement) to applied electric field (or voltage). So, measuring displacement tells us strain - we are now off to the races!

However, putting 100V over a typical PZT ceramic generates only 40 nanometers of displacement. You can only measure that with a precise fiber optic light displacement sensor, such as those offered by Philtec .

An alternative solution is to use a laser vibrometer and drive the piezo at a high but still off resonance frequency, say 5kHz. Even though displacement will be the same between 10Hz and 5kHz, the velocity increases dramatically, thus allowing for accurate measurement of velocity and hence calculation of displacement.

There is something tricky about capacitance measurements

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 18 Aug 2021 19:46:39 GMT

Why capacitance measurements?

Capacitance measurement have a lot of utility in ultrasonic transducer analysis. This is because it is highly repeatable, simple, and highlights the performance of the crystals.

What frequency should we measure capacitance at?

Measure capacitance at a frequency much lower than resonance. Let's say, at least 10x lower than your lowest resonance frequency in your structure, the minimum being 1 kHz. Measuring capacitance at too low of a frequency will (sub 1kHz) may result in contributions from space charge rather than the desired contributor to polarization.

Did I mention there is a caveat?

But be careful, there are acoustic resonances in your system that may be much lower than your resonance frequencies. These will alter your capacitance and drive the loss properties way up.

In order to decide the best frequency to use for single frequency capacitance measurements, perform a slow frequency sweep from 0.8 kHz to 15 kHz (or whatever range is LOW frequency for your application) with an impedance analyzer and look for a continuous or flat change in phase - this is a stable region without subliminal resonances. Choose a nice round frequency value for testing in this region. The best practice is either to use 1 kHz or 10 kHz.

Stop Using Fixed Boundary Conditions On Your Piezo Simulation

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 17 Aug 2021 13:53:06 GMT

The question was poised to me:

I received a question from someone who was doing a basic piezoelectric simulation - they were applying a force, and they wanted to measure voltage

The values they calculated, however, were much smaller, just over half of the voltage he expected.

So, what was the problem? BOUNDARY CONDITIONS.

Here is a link to my youtube video explanation if you are into watching videos: https://youtu.be/uTLpeb2ooAs

If not, read on!

What's wrong with fixed boundary conditions?

The piezoelectric constitutive equations, and the definition of the voltage constant “g” assumes there is no restraining force on the piezo.

However, in order to do a static simulation you have to put a fixed constraint somewhere.

The constraint does not allow the piezo to deflect outward according to the Poisson's ratio, so this reduces the Z-axis strain and hence reduces the charge and voltage generated.

The easy solution

Upon reading this solution, you are going to say "Why didn't I think of that!"

The solution is to use a low frequency harmonic analysis to avoid the requirement for a fixed boundary condition to constrain the model. For example, specify the forces and supporting forces at 10 Hz, instead of doing a 0 Hz frequency static simulation. This way, you don't have to apply the fixed boundary condition constraint. If you think about it, DC or static is just a very low frequency. Thus, using 10 Hz or even 1 kHz will work.

Piezo Fundamentals: Two origins of piezoelectricity

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 16 Aug 2021 16:45:08 GMT

What factors contribute to piezoelectricity? YouTube link: https://youtu.be/-ynVKJkFKsE

In this post, I am sharing a video I've made for explaining the two origins of piezoelectricity. Simply put, they are:

Unit cell contributions
Originate from non-symmetric structure of the piezoelectric crystal
Domain wall motion
Domains are "sub-lattices" in a crystal. The movement of different domains interfaces or "domain wall" adds a significant contribution to piezoelectric material properties. This is especially true in PZT materials

The What, the Why, and the How of Impedance Analysis

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 13 Aug 2021 17:22:03 GMT

My estimations

My estimate is that about 75% of ultrasonic transducer companies are using impedance analysis to capture relevant data.

Of those companies, my estimate is that only 5% have a good understanding of impedance analysis, which is THE essential tool for ultrasonic transducer analysis.

How do I know this? I work with several piezoelectric and ultrasonic transducer companies and have had many many sales calls with such companies (slightly less than 1 to 2 calls per week for the last year).

The "what" the why" and the "how"

This brings me to the point of this article, which is the “what”, the “why”, and the “how” of impedance analysis.

What

The 75% of companies that use impedance analysis have partially achieved the “what”, that is, they are routinely taking impedance measurements and are aware what data they should capture.

Why

But of those companies, only 5% have a good understanding of what they are looking at. This is the “why”. Only those 5% can deeply explain the physical phenomenon behind what causes the impedance response. I created my course on impedance analys i s to help companies get to this stage, to perfect both the “what” and the “why”.

How

Even a smaller subgroup are those companies who can use impedance data to stare deeply into the soul of their devices. These companies are able to make nontrivial analysis based on impedance data. They make surprising decisions based on what they see, what they can explain, and what they can back up with other experimental proof. I'd put this percentage at 0.5% or 1/200 companies. This is the “how” level. Top notch.

The method to achieve the "how" level

How can you get to the “how” level? No amount of instruction can get you there. You need to do purposeful experiments for learning while having mastery of the “what” and “why”. I'd like to say I have achieved this though my PhD studies where I was afforded the opportunity to dig in to the subject very deeply. But you don't need to go back to school. This level is open to any company willing to go through the first two stages and then willing to dedicate time to feed their fundamental curiosity regarding physical relationships through experimentation.

Does your ultrasonic transducer move at cheetah speed?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 10 Aug 2021 13:08:29 GMT

A transducer with the velocity of a cheetah

Is your ultrasonic transducer faster than a cheetah? Of course your ultrasonic transducer doesn't run across land, as a resonating device it oscillates about a reference point. However, if we back calculate the displacement of a transducer oscillating at the speed of a cheetah, assuming the transducer is working at a classic 40 kHz, here is what we get:

Velocity = Displacement * 2 pi * frequency

That give a displacement of 115 um.

An amazing acceleration

The displacement of ultrasonic transducers are puny, but the velocity is formidable. However, the acceleration is AMAZING!

Acceleration = Velocity * 2 pi * frequency

Acceleration = 7,288,495 m/s^2

A cheetah can reach a speed of 100 kph in three seconds, which is an acceleration of 9.25 m/s^2.

Therefore, the acceleration of the transducer is ~800,000 times larger than that of a cheetah. WOW! This high frequency acceleration is the cause of large localized forces in many transducer applications.

Ultrasonics and Antarctica

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 09 Aug 2021 15:44:16 GMT

Colin O'Brady was the first person to cross Antarctica/South Pole on foot, unassisted by machine, animal, or wind. (please keep reading, I am going somewhere with this).

His journey was highly disputed because his approach to achieving this feat was by creating a “criteria for ever-more finely sliced accomplishment.” Basically, he figured out a way to cross the South Pole in the easiest fashion by foot in order to increase his chances to accomplish the feat. People said he cut corners and, for example, trekked on a beaten path of vehicles instead of going head-on against challenging terrain.

We ultrasonic folks have a lot to learn from Colin. Unfortunately, me and other engineers get ego-struck and try to accomplish things the hard way, just because we think it can be done. Or, we just head into things head first and think that we will just figure it out as we go.

To put it frankly, “taking the hard path” across the South Pole resulted in some men being frozen solid when crossing by foot. Colin made it across because he was smart, but that doesn’t mean he was not equally as gifted.

Don’t get frozen solid on your ultrasonic/piezoelectric transducer projects. Achieve the minimal viable product, do complete system testing often, and don’t skip measurement steps. Otherwise, your company’s transducers will just be some forgotten ice cubes in a closet somewhere in your lab.

Is high stress the best?

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 07 Aug 2021 19:34:33 GMT

In order to have the highest electromechanical coupling in a power ultrasonic transducer, you need to place your piezo crystals at the nodal point of the assembly. However, in certain situations you don't want to do that. Because the nodal point is at a high stress location, the piezo will be necessarily undergo large stress for any level of vibration. Here are two points to consider when specifying the placement of your crystal which may actually warrant not placing your crystal exactly at the nodal point:

1. The cyclical stress limit of the piezo ceramic may actually limit the maximum oscillation amplitude which a design can reliably achieve.

2. When the ceramics are not placed at the nodal point, the Q of the assembly increases as now (A) the metal components contain more strain energy per unit of oscillation and (B) you removed component interfaces at the nodal point, which are hubs for power loss.

What's your transducer IQ level?

Sat, 07 Aug 2021 03:05:03 GMT

IQ is basically a measure of a person's ability to recognize patterns. It is your ability to make non-trivial connections.

A person's IQ is certainly put through the test when developing, enhancing, or maintaining ultrasonic transducers.

I know that experienced ultrasonic transducer engineers can tell when the impedance response of a transducer looks “funky” even though they can't fully explain the cause. Those engineers are using pattern recognition, which is a function of IQ and experience:

However, I'd like to add another factor to this discussion. That factor is “understanding.” IQ and experience are incredible forces. These forces are amplified with the “fulcrum” of understanding. Simply put, this is the “why?”. I argue that your ability to overcome ultrasonic transducer challenges is the product of IQ, experience, and UNDERSTANDING.

One method to start building your understanding of the impedance response of ultrasonic transducers is to take my “to-the-point” course on the subject.

Formal learning aside, you and your team should take the time to do learning experiments. Often times, the only experiments and tests we complete are with a commercial transducer and a realistic setup (this is not good for learning!). These systems are complex, and often it becomes hard to weed out essential observations needed to build understanding.

Never stop asking why - in your heart you know when you are stopping yourself from asking the hard questions.

New Impedance Analysis Course!

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 04 Aug 2021 21:38:31 GMT

New course offering!

After reflecting on several of my recent client engagements, I realized one of the most important areas I add value is in instruction of the fundamentals of ultrasonic and piezoelectric device analysis. Toward that end, I decided to start creating formal online courses to provide a structured environment to facilitate that learning. My first course will be on impedance analysis and will be available August 11, 2021 (1 week from today!).

Course on impedance analysis of ultrasonic/piezoelectric transducers

Impedance measurements are the most fundamental measurements one can do to characterize, analyze, and develop ultrasonic devices. Many engineers working in this field have an incomplete understanding of this topic, so this course will help fill their knowledge gaps and increase their confidence and competence.

You can find more information about the course at the following link:

Impedance Analysis of Ultrasonic/Piezoelectric Transducers

All the topics in the course are extremely practical and fundamental to working in ultrasonic transducers. I am just a few edits away from having all of the content uploaded.

Why start with a course on impedance analysis?

Most textbooks start with teaching students with anisotropic material properties and the crystal structure origin of piezoelectricity. This loses most people and quite frankly is not very important or practical for a device designer. What is important is a working knowledge of phenomena which can help lead a transducer developer to important analysis and design decisions - the best way to accomplish that is with understanding the impedance response.

Please contact me if you are interested in this course and help me spread the word!

Reliability vs. Variability

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 29 Jul 2021 16:01:07 GMT

Are you concerned about reliability?

Are you concerned with the reliability of your ultrasonic transducer? Are you concerned about delamination, fracture, and depoling? You can solve this by utilizing a deep understanding of your transducer to reduce variability based off of the universal principle that higher power operation results in more failures.

Let me give the world's most simple solution to the problem of reliability- just use less power.

You may pushback and say that the performance is going to get worse if you do that.

If you want to reduce power without negative consequences, you need to tighten up variability.

An example

For example, say your performance spec requires 3um of displacement and your current devices run at 5um +/- 1.5um. In order to improve reliability you need to reduce the performance to 4um with a variability of +/-1.0um.

The moral

The easy way to fix reliability is to spend more money on a tougher design. The elegant way to fix reliability is to use a deep knowledge of factors causing variability to reduce variation and bring the mean level of performance closer to the necessary specifications.

Beware of the FEA Dungeon and Save Your Friend!

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 27 Jul 2021 15:37:34 GMT

The top problems I help my clients solve are (1) getting to a better understanding of underlying physics (2) reduction of variability (3) improvement of reliability.

The Beast In the Dungeon

The application of FEA to ultrasonic devices can solve all three of these problems. However, there is a beast at the bottom of the dungeon if you choose to utilize this tool. That beast is “matching FEA and experiments.”

You say there is no beast? Really?

It’s all too easy to just take a few steps into the dungeon and say “There is no beast, all I saw were little bats.” You say “Matching FEA with ultrasonic devices is not tough.”

I challenge you - I say you did not go far enough down into the dungeon. How do I know that? I can just ask you three questions:

Three questions to know if you really went deep in the dungeon

(1) How many different samples did you use for your experimental comparison?

(2) Does your model include nonlinearity and how are those physics validated with experiments?

(3) Does the model applied in different conditions still match experiments?

Some advice for you

You did not go far enough down to see the beast. Also, for the sake of your life I must tell you something. There is no prize for slaying the beast. The point of going into the dungeon is to save your friend Sir Done-Is-Better-Than-Perfect. The beast is a danger and a distraction, but not the prize.

Let me introduce you to your better half – simple modeling approaches

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 26 Jul 2021 16:07:17 GMT

You are single, you head over to a bar, and who knows? You just might finally meet your better half. When you get there, you pull out your laptop, login to your company's computing workhorse remotely, and fire up your FEA program of choice.

Obviously, since all of your company’s ultrasonic transducer models are 3D CAD models, you always simulate 3D models. Just import, clean things up a bit, and you are ready to start meshing, assign materials, and place boundary conditions.

You follow best practices of meshing, and perform convergence studies to things started. Seems like 5 million nodes is a sweet spot . You decide to couple the fluidic domain to the elastic simulation and set the optimization simulation to start and you call it a night.

Come Monday.....

Monday morning, you check on your simulation and… the simulation seems like it will be done on Friday. Meanwhile, another colleague of yours is fooling around with parts in the lab, doing his own method of optimization.

“He’s a fool,” you think to yourself.

However, because he immediately gets results on what is working and not working, he is able to present his results to the team all week. The team asks you about your progress - what can you say except “In progress.”

Friday

Friday arrives. Your colleague’s experiments looked promising, but ended up not being repeatable. You open up your simulation Friday morning and realize that you forgot to assigning bonding conditions between components and the results also just looked too “wiggly” (the word for transverse resonance modes for commoners).

Months later

Both of you will continue for several months, improving your techniques but making no progress. I can’t tell you how the story ends, but here is moral of the story, my friends:

Simulation gives insight that experiments cannot, but it can also be paralyzing. Establish simple models that give you definite progress, instead of going all out for a home-run (or gold medal).

Are you using 2D axisymmetric modeling? Are you using 1D modeling? Are you using 0D modeling? Have you done any hand calculations?

Simple modeling approaches are the better half of an engineer.

I look at FEA as a tool for insights, not design.

Driving Ultrasonic Transducer Simulations Without A License

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 25 Jul 2021 13:40:36 GMT

Don't let this be you!

Improve your relationship

Finite element analysis of ultrasonic transducers is very much like being in a committed relationship - even if you cannot grasp all the physics behind her behavior doesn’t mean you wouldn’t immensely benefit from investing time in getting to a deeper understanding.

Understanding is key

One of the biggest issues that engineers make when doing finite element analysis of ultrasonic devices is that they don't understand the piezoelectric effect. You may think that how could this be true? Could a professional working on ultrasonic device simulation implement the piezoelectric phenomenon but has little to no understanding of it? Well, I have witnessed it on many occasions that the basic effects of the converse and direct piezoelectric effects are not understood by simulation engineers. This is because their previous experience lacks a background in piezoelectric materials, and piezoelectric transducers are not taught at a fundamental level in universities.

Engineers coming from different disciplines often don’t have an understanding of the concept of electromechanical coupling. Even more rare is the awareness of the factors which cause differences between simulations and experiments.

Finally, learn your license and learn to drive

FEA tools are powerful, perhaps the most powerful vehicle in development an engineer has. Without “learning to drive,” you can still drive fast, but you will learn by crashing.

How do you learn to “drive” piezoelectric simulations?

STEP 1: Compare theory and FEA

Firstly, compare finite element simulations with hand calculations of the converse and direct piezoelectric effects. Here are my tutorials on those topics:
Simulation of the “direct” effect (sensor | input force output voltage)
Simulation of the “converse” effect (actuator | input voltage output displacement)
Next, familiarize yourself with the impedance response and factors that change it and what those changes mean to the electrical and mechanical performance. Here is a tutorial to get you started on understanding the impedance response from a theoretical and FEA perspective:
Impedance Frequency Response of a Piezoelectric Element Using COMSOL

STEP 2: Compare FEA and experiments

In order to achieve a complete understand of how material properties, boundary conditions, and other parameters affect ultrasonic devices, you must do experiments and compare them with theory and FEA
Here are some basic experiments that can compare to FEA help you get started on your holistic understanding
Impedance response of a piezoelectric disk
Impedance response of ultrasonic cleaning transducer
Impedance response of a piezoelectric disk bonded (by you) to a substrate
I recommend using the impedance response for comparison because impedance analyzers are standard tools in most laboratories and provide both electrical and mechanical data in a format that is easy to compare to FEA

Is this just homework?

This may seem like a lot of homework, but the flip-side of not having a holistic understanding is a sub-par competence of your modeling efforts.

What FEA program should you use to simulate power ultrasonic devices?

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 24 Jul 2021 12:40:15 GMT

This is the first post in a series describing the common mistakes and misconceptions that engineers make when simulating an ultrasonic transducer in finite element software.

Do you really need piezoelectric physics?

The first mistake they make is that they assume they need to use piezoelectric multiphysics modules in order to simulate those devices. This may at first look obvious - if you want to simulate a piezoelectric device, you should be able to model those physics. This is fundamentally wrong assumption because simple standard elastic material physics (standard in any FEA program, expensive or inexpensive) are sufficient to determine many key performance characteristics of ultrasonic devices.

Resonance Simulation

Firstly, take the resonance frequency and mode shape (displacement profile, nodes, antinodes) - modal analysis solves for the resonant modes and their frequencies. You do not need to perform harmonic simulations in order to determine the resonance frequency and the displacement distribution, nor do you need to include piezoelectric phyiscs in 95% of cases.

Static Simulations

Secondly, to perform static simulations to determine displacement without piezoelectric physics, you can apply forcing on the faces of the piezoelectric material according to the piezo crystal's own blocking force. Yes, you will have to implement a hand calculation in order to determine what force you need to apply, but the process is not complex!

What could go wrong?

What happens when you use piezoelectric physics when you don't need to is that you will (1) over-complicate the problem and (2) overstretch your goals for the simulation.

When the FEA modeling gets more complex, there is additional time spent in perfecting simulations and running optimizations. Understand that your FEA model is in fact a MODEL not THE REAL THING . There are many differences which occur in a real prototype that cannot be reliably predicted with FEA. The two largest phenomena that come to mind are non-linearity and component interface effects.

Imagine you are going on a vacation. You have to drive there. The "car ride" is the FEA modeling step and the "destination" is your prototype.

The Simple Principle

So, should you use piezoelectric physics in your modeling approach? If you don't know or cannot explain concepts in piezoelectricity, you should not. In that case, you should focus on simulations focusing on elastic material physics only, and continue your studies on piezoelectricity. A plus side of this approach is that you will have simpler simulations, an emphasis on prototypes, and also the ability to use lower cost FEA programs and modules.

Where did we go wrong!

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 20 Jul 2021 14:05:21 GMT

Root cause analysis of failure, variability, or other undesirable effects unavoidable in ultrasonic transducer product development.

What is avoidable, in many cases, is realizing that your product's issues from customer complaints. That being said, many times we discover issues regarding our device from customers because our production testing methods are incomplete to sufficiently guarantee performance.

There are many steps going into the production of a product, and missteps at any portion of the chain is going to result in a faulty final device.

In the ideal case, I recommend to seek out anomalies through testing as far back as possible. This could mean comprehensive testing of piezoelectric crystals before assembly and testing bulk metal materials before machining. It could also even mean composition analysis of each batch of crystals.

Some of these suggestions may seem extreme, but even if these tests save your company from doing ONE root cause investigation, it will reward you SEVERAL TIMES MORE than the expenses of your comprehensive test regimen.

The k31 mode - the original multilayer

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 19 Jul 2021 16:03:10 GMT

Some people think that the way to increase displacement in a piezoelectric transducer is add more layers or utilize an optimized resonator assembly. Don't limit your thinking.

The "original multilayer" aka displacement enhancer is actually the "k31" mode of a piezo.

When we apply voltage to a piezo, there is expansion or contraction in the polarization direction - that is the k33 mode. In this case, the displacement is equal to the d33 coefficient multiplied by the voltage.

However, the same piezo also exhibits transverse displacement (along the width) due to the Poisson's ratio - this is known as k31 operation. If we solve for the displacement in this direction, we will notice that the length (or width) will multiply the displacement. So, for a piezo bar with ratio 1mm thickness x 5 mm width x 20 mm length, the displacement will by multiplied by 20 - WOW!

Here is a complete derivation:

Burger or Bookcase?

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 17 Jul 2021 20:05:03 GMT

Typically when we think of multilayer piezoelectric stacks, we think of the " burger." That is, piezo layers poled in the thickness stacked on top of on another in an alternating polarization configuration. This provides huge advantages in terms of achieving high displacement with low voltage applied.

But the opposite is also true...

Given an applied force (or applied displacement) the generated voltage will also be small for the burger topology.

So are multilayers doomed when it comes to using them for sensors? Not at all! Let me introduce you to the bookcase topology. In the bookcase topology case, the actuation ability would be similar to a single bulk piezo crystal of the same size. However, if you take the bookcase topology and wire the electrodes correctly... VOLTAGE WILL ADD between each layer, plus the long length of each element will further increase the voltage!

So what is best for energy harvesting? It depends on if you need more voltage (usually the case) or more current.

The Boxing Method

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 17 Jul 2021 01:22:16 GMT

The most valuable tool that an engineer has is a box. I'm not talking about a physical box, like a plastic box, metal box, or highly padded box used for transportation of sensitive equipment.

I'm talking about taking a piece of paper and drawing a box.

Sounds worthless? It's actually priceless.

Before a meeting, instead of sending out an agenda, send out a graphic (you can make it in powerpoint) with a box. Inside the box, you will write everything that is in scope for the meeting's discussion. Outside the box, you will write down everything that is out of scope for the meeting. I call this boxing.

The boxing method does two things:

(1) It creates a visual construct. People are hardwired for the physical world, so having a visual helps to internalize the focus of the meeting

(2) It explicitly requires the meeting organizer to specify what is not on the table for discussion. How often have we come to meeting to discuss one issue and the meeting drags on discussing something much different?

Does your team use visuals to keep the team focused and aligned? Hit reply and let me know!

Base Excitation or Forced Excitation?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 15 Jul 2021 21:02:22 GMT

If we draw a similarity from a piezoelectric transducer to a Mass-Spring-Damper (MSD) system, would piezoelectric forcing be akin to base excitation (specified displacement of the base) or force excitation (specified applied force).

Let's assume:

The movement of the mass is akin to the kinetic energy in the system.
The stretch or compression of the spring is akin to stored potential energy.

Now let's consider the application of a step voltage and the reaction of the piezo transducer.

According to the forced excitation model , we equate the applied voltage to the force. In this case, no immediate increase in energy would be present. The mass will take time to move and the spring will thus take time to stretch.
According to the base excitation model, the base excitation would be equated to applied voltage. If we specify a sudden step-wise displacement, we have immediate energy in terms of the compressed spring. The mass then has to react and gain momentum.

I believe the base excitation model is more accurate. When a voltage is applied suddenly (step response) to a piezoelectric transducer, the natural strain state of the piezo is immediately shifted, elastic energy immediately appears, and the piezo then gains velocity and displaces over time until it settles at its new equilibrium strain. Deep stuff.

Does your transducer measurement plan seem like a 5-legged chair?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 14 Jul 2021 16:09:31 GMT

Do you feel like many of the transducer measurements you are doing seem redundant like a 5 legged chair? For example, why would we use a d33 tester on crystals when we do impedance analysis? We get much of the same information from both.

Why measure transducer velocity with a vibrometer when system performance parameters and electrical measurements already give a good indication of how well a transducer is performing?

There are three reasons why you should have some redundancy in your measurement methods:

Some methods are more error prone than others. Multiple measurements using different principles give confidence that no single method is in error
Each measurement method is in fact a little different even though similar phenomenon are measured. Therefore, each gives us a nuanced way of looking at the data
One measurement method may be superior than another for reasons you cannot 100% predict. Therefore, including multiple measurements protects you from using an insensitive measurement method

If done right, most standard characterization on piezoelectric transducers can be automated. My opinion is that it is a wrong methodology to seek the minimum number of measurements.

Resonance measurements, I choose you!

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 13 Jul 2021 18:26:55 GMT

Excitation levels in terms of mechanical oscillation are WAAAAY different for resonance and antiresonance frequencies as driven by a low signal impedance analyzer. Resonance excitation can be 10 to 1000 times higher for the same voltage settings.

In piezoelectric devices, excitation levels make a huge difference on performance, so the antiresonance measurements are sorta wrong and cannot theoretically be used with the resonance frequency for calculations. If we assume the excitation level is so small, we don't have to worry about this. Did I ever mention that assumptions are the fodder for inconclusive results?

The take away message is this: if your resonance and antiresonance frequencies have an impedance difference of more than 5x, you should strongly consider using equivalent circuit analysis using only resonance frequency analysis to determine the coupling factor.

Please hit reply if you need more clarification on this!

Documentation tip for FEA

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 12 Jul 2021 15:43:18 GMT

We as engineers have the tendency not to document our work and to show our colleagues difficult to digest presentations in their raw forms. This includes a common practice of showing people raw calculation Excel files and also showing simulation results directly from the FEA software. I'm personally working hard to break this habit, but it's tough!

In FEA, documentation can be a challenge as exporting results, especially animations, are quite annoying. Here is pro-tip I have found super useful for that:

In Microsoft Powerpoint, in the INSERT -> MEDIA ribbon, there is an option of "Screen Recording. Next time, instead of exporting your FEA animations and then importing them, simply use the PPT screen recording tool to capture your animations directly into Powerpoint

800 page book on product development

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 12 Jul 2021 02:09:34 GMT

I have a 800 page book on product development according to the DFFS method (Design for Six Sigma). The book covers several stages of engineering product design and includes very specific checklists, gates, evaluation criteria, customer need research, statistical analysis methods and more.

When should you follow such a detailed product development method and when should you just follow the classic "Build, Test, Fix" approach? Let me share my thoughts.

If (a) the value of quality is very high and (b) the cost of quality is high, then you need to follow a strict process oriented approach, as that is how you nail down quality.

By "quality", I mean the statistical level of adherence to specifications identified as important by your customer.

Now, if quality is easily achievable or is not of the upmost concern, then you should follow a creative process of product development by doing multiple prototypes.

Your product development team likely needs a method in between 800 pages of process and "Build, Test, Fix". Have you identified a methodology that is working for your team? Hit reply and let me know!

FEA knowledge transfer

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 10 Jul 2021 13:16:54 GMT

At any given ultrasonic transducer company there is usually an FEA guru who, consequently, is often the ultrasonic expert on the team.

FEA simulation can be readily made in to a process by which it can be taught to others, thereby increasing the bandwidth of the product development team.

It takes a huge amount of time to make proper written instructions. However, I would suggest that you use screen recording to document the process by which your team's expert creates simulations for instructional purposes.

Windows OS has a really easy method of screen recording. Simply press Win+Alt+R , and a recording will start. The rest is pretty intuitive.

Why get a deep understanding?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 08 Jul 2021 11:26:02 GMT

Why spend time to understand the the underlying physics of your ultrasonic transducer? Four simple reasons:

(1) To help you discern when you are making incorrect measurements

(2) To help you discern when something is grossly wrong with your device

(3) So you don't try random things to fix problems based off of faulty intuition

(4) So you will be able to take incoherent data from several sources and make logical engineering decisions from them

Measurement method pro-tip

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 06 Jul 2021 18:59:16 GMT

The easiest way to achieve more accurate and repeatable measurements is to take more of them. However, this will take significantly more resources if more samples are to be tested and it will take significantly more time if experiments are to be repeated.

That being said, the first tier of improving repeatability and accuracy of measurements is to take three measurements at each measurement instance. The benefits are:

The average value will get you a more accurate and repeatable result
You can determine the standard deviation of individual measurements, by assessing all the repeats together
The execution time of the experiment does not increase much

Does "build, test, fix" equal "fail"?

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 04 Jul 2021 19:59:01 GMT

When should you resort to fast prototype iterations for your ultrasonic transducer development and when should you delve deep into analysis and thoughtful design? If done incorrectly, quick prototypes can lead to “shooting blindly” and deep analysis can lead to “analysis paralysis”.

It’s a complex question, but here is one easy rule of thumb: if you can tell exactly why your prototype did not work as expected, then you are in a good position to do quick iterations. However, if you cannot discern the reasons for low performance and variability, you need to take a structured approach.

Development is cheap and problem solving is expensive

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 01 Jul 2021 12:54:03 GMT

If you have worked on several ultrasonic transducer products, you will easily be able to provide several technical problems that you had to solve. I believe we as engineers don't give enough attention to not letting the problems happen again.

Yes, we know how to fix the problem quickly. But, we don't take active steps to prevent it from inception.

Development is cheap and problem solving is expensive. In fact, problem solving is 10x more expensive than development in my opinion. Spending a significant amount of resources to prevent a problem is still cheaper than having to fix an unplanned problem.

An example is regarding piezoelectric crystal suppliers. Most transducers have only one crystal supplier, and companies are constantly getting burned by issues coming up with their supplier in terms of property variation and even price gouging. Having more than one supplier is inconvenient and difficult to maintain, but it's an important step to take once your device is reaching early stage maturity.

Bring the heat

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 30 Jun 2021 04:07:08 GMT

Want to know the polarity of your piezo ceramic element? You could bang on it, and infer the polarity from the voltage generated.

An easier way to do this is to apply heat slightly and note the positive voltage. Even your breath will do as a heat source.

The terminal with the higher potential deserves a "dot" signifying that a positive voltage was applied to that terminal during poling.

Heat causes change in spontaneous polarization, which then creates surface charges due to charge conservation.

Crystal specifications for constant voltage drive

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 29 Jun 2021 02:02:31 GMT

Let's take into consideration an application which applies a constant voltage to an ultrasonic transducer which is driven at the resonance frequency via frequency control around phase.

What is the important crystal specification that would allow you to achieve performance over a threshold in terms of output power?

Firstly, I recommend having some lenient tolerances around what is considered normal for all properties including dielectric permittivity, compliance, electromechanical properties, and loss coefficients.

Now, assuming that your crystals are "normal" statistically speaking, the mechanical quality factor measured at high power would be the most important single parameter which signifies high power performance.

Sadly, the measurement of this parameter does not have a industry standard method with standard equipment from big name electronics vendors.

Are Six Sigma calculations incorrect?

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 26 Jun 2021 20:43:24 GMT

If you use statistical definitions of the standard deviation to calculate variability, you will readily calculate that +/- 2 sigma (standard deviations) would result in ~5% defective product. +/-2 sigma encompasses ~95% of all the samples. 5% defective product for transducer is not bad, as long as you can catch 100% during manufacturing testing. This is definitely normal for many ultrasonic transducers assemblies.

That being said, what you will usually read in "Six Sigma" training materials that a two sigma process results in 30% defective product. So what is going on? Why is there a difference?

Six Sigma methodology adds an extra 1.5 sigma to account for variation in the process in the long term. Obviously, we cannot do experiments and tests today that will tell us the variation of tomorrow. Therefore, we assume 1.5 sigma to be the deviation in the mean of the process in the long term. The actual amount may be much more, or in a rare event the variation will be less.

Don't assume that the transducer testing that you have just completed in the lab, even if it has 100 samples, will properly describe the long term results. There are so many sources of deviation, which include test methods, crystal property variation, and variation in actual part tolerances (both dimension and features).

A calibrated stopwatch?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 25 Jun 2021 15:51:58 GMT

The measurement of time is perhaps is only quantity that can be measured extremely accurately by very low cost cost devices. However, when we look at qualification tests in regulated industries, we still require that stopwatches used for measuring time during an experiment to be calibrated.

The need for calibration is not driven by the need to ensure the watch is not wrong, but it is driven by the need to know that the watch is right.

This rule is true for all processes of manufacturing, data collection, and data analysis.

Are the validation for your processes based of the need to show *error-free operation* or the need to show *correct operation*? I believe the latter is superior

What does your company sell?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 24 Jun 2021 12:47:16 GMT

You may be just an engineer, but do you know what your ultrasonic transducer company sells?

You be tempted to think that it is the final product - the ultrasonic welding transducer, tools, and driver - or maybe the ultrasonic surgical handpiece, consumables, and main console.

As far as the engineer in you is concerned, what your company sells is the systems and processes by which your device has been developed, assembled, tested, and maintained.

If you don't have excellent systems and processes, your company is losing money even if they are making money! That is because such products development & support will consume an unnecessary amount resources, thereby resulting the lost opportunity for new development.

3-point bending test of hard and soft PZT

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 19 Jun 2021 11:02:29 GMT

Who is the winner?

Who is the winner of a three point bending test? Hard PZT (PZT 4 and PZT 8) or Soft PZT (PZT 5A and PZT 5H)? The study by Abramovich et al. 2013 describes a three point bending test on 50 samples of each of these materials. The link to the article is here . The testing conditions were open circuit.

The results show that PZT 5A and 5H are able to exhibit more strain and more stress in an off-resonance actuator scenario before fracture than hard PZT.

How do these results inform us regarding an ultrasonic transducer? Well, for high power applications, we traditionally think of hard PZT being the king due to its low heat generation and high Q. However, ultrasonic transducer transferring energy primarily through epoxy bonds, system Q is very low, and actually approximately equal between hard and soft PZT assembled devices.

In that case, tolerance to high strain is important; the results in the article described here indicate that fracture limits of soft PZT are superior to hard PZT, thus it would be a superior choice for such an actuator. Very non-intuitive.

The square beyond compare!

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 17 Jun 2021 15:49:51 GMT

Sine waves are great for driving ultrasonic transducers. The resulting current waveform, more or less, will have pristine harmonic contents which will be great for analysis and feedback control. You also therefore avoid driving other harmonics which will create heat and cause unwanted oscillatory behavior. Sine waves can also be properly and easily amplified (or reduced) by a transformer in order to deliver maximum power to the transducer. Digital amplitude control is also a common feature of sine wave drive circuits.

So why would be drive our transducer with a square wave, which by its very nature consists of many harmonics and can be quite rigid with regards to amplitude control? There are two aspects of square waves which are awesome:

(1) Square waves drive signals are easy to generate.

(2) The half bridge and full bridge drivers used to generate square wave drive signal have an extremely low output impedance. This means that the drive voltage will not change at all due to changes in impedance of the transducer during operation. You cannot say that for almost all sine wave drive circuits, where such impedance change can cause instability.

Where to put my piezo?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 16 Jun 2021 19:15:47 GMT

Do you ever wonder why we put our piezo material at the nodal point (no displacement) instead at the antinode (highest displacement) in resonant ultrasonic transducers?

Our logic may tell us that the antinodes would be best for piezo material as the crystal would apply force over a longer distance during a cycle.

That would be true if piezoelectric materials applied *force*.

They don't apply force, they apply stress. Does that seem trivial? It's not.

Piezo materials apply stress as the surrounding structure undergoes strain, thus adding energy into the system. The larger the strain of the surrounding structure, the more energy is introduced.

Transcend your transducer assumptions

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 15 Jun 2021 16:43:17 GMT

As a consultant who focuses on providing advisory support to engineering teams developing ultrasonic transducers, I hear the following statement quite a bit:

"The new batch of transducers is different than the last one! We used the exact same materials, the exact same assembly steps, and we tested in the exact same way. But we have different results!"

I think ALL of those statements/claims/assumptions can be challenged despite their external truth.

If performance is different, there is a physical or system difference. Duh!

The problem is not that the same methods creates different results.

The problem is that a method to characterize the system/physical differences causing difference in performance has not been developed or implemented. Stop "kicking the can" and dig in to the meaty analytical and experimental work that will give you clarity instead of confusion.

What the frequency?

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 15 Jun 2021 02:32:24 GMT

The frequency for your ultrasonic transducer is not arbitrary. It (more or less) reflects the frequency for the highest amplitude of oscillation, assuming you are analyzing a resonance operated device.

But why do we different devices have different frequencies frequencies? Isn't ultrasonic just ultrasonic?

Why not make all ultrasonic devices at 20kHz? I'll quickly address two reasons:

[Space constraint] Because we need a device to be small, we are naturally constrained to work with higher frequencies. This is because frequency is inverse to size (sound bounces around more "frequently" in a smaller geometry)
[The desired effect requires a certain frequency] High frequency sound has shorter wavelengths, which is critical to consider for diagnostic ultrasonic applications. Lower frequency transducer (eg 20kHz) are able to transfer a large amount of energy, so that becomes the premium choice for welding applications

I am non-linear, so what?

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 13 Jun 2021 17:59:04 GMT

Your transducer is nonlinear - let's get over that.

But what does that practically mean? The performance and characteristics of your transducer will depend on testing conditions and drive power levels. This means that there will be stark differences between your impedance analyzer measurements and performance in your final application.

Ultrasonic resonance depends on amplitude

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 10 Jun 2021 17:58:32 GMT

The resonance frequency in ultrasonic transducers is affected by the amplitude of power or current delivered. In the figure above, an LCR circuit's admittance is plotted for a linear LCR circuit and a non-linear LCR circuit. In the non-linear circuit, the capacitance is a function of current.

As the current increases, the capacitance increases. The result of this effect is that the resonance frequency decreases and a sharp transition is seen at the new resonance frequency.

For the plot above, the LCR values were:

R=1110 Ohm, L =0.19 H, and C= 15.1nF.

In the nonlinear resonance, the R and L were the same, but the capacitance was defined as:

[15.1 nF]*(1+current/0.007)^2

By using small frequency step sizes, I did not have to get fancy with the determination of current, as I could just use the current at the previous frequency step.

This representation of capacitance results in a similar maximum current amplitude to the linear model, but gives the distinct nonlinear transition and resonance frequency shift seen when doing a constant voltage sweep over the resonance frequency of an ultrasonic transducer.

For small signal excitation, the results are linear. However real-world ultrasonic transducers do not operate with "small signals", so finding appropriate analysis methods is critical for a deep analysis.

Constant current equal linear resonance

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 08 Jun 2021 03:15:50 GMT

The two figures above show the same piezo transducer driven over its resonance frequency with two different driving conditions, *constant voltage* and *constant current*.

The left figure shows a constant voltage drive - notice the "drooping over" of the admittance with increasing amplitude - this is a nonlinear phenomenon as power input strongly increases at resonance with constant voltage drive.

The figure on the right shows a constant current excitation scheme - notice that the response is symmetrical. At resonance, current very closely equates to input power, so by controlling current to be constant, we eliminate nonlinearity and thus get a symmetrical response. Yup, we can calculate Q-factor using traditional bandwidth calculations now. Phew!

Linear-ize it!

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 04 Jun 2021 20:05:16 GMT

A huge bulk of analysis relies on system linearity for validity. Without paying attention to the non-linear nature of your system, you will end of up comparing apples to oranges, so to speak.

The best way to "linear-ize" your system is by normalizing your measurement method. Introducing a scaling factor after data has been collected is wrong. The scaling factor must be introduced at the time of measurement to measure the correct system behavior.

The most common example of this is the use of constant current drive conditions to calculate the mechanical Q-factor using power bandwidth calculations. And you guessed it...the Q factor calculation using bandwidth requires system linearity.

More on this type of measurement in the next post. Stay tuned!

Are you linear?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 03 Jun 2021 15:19:27 GMT

Most equations for analysis of piezoelectric materials, including extraction of material properties and equivalent circuit analysis, assume your system to be linear.

Firstly, know without a doubt that your system/device is not linear. That doesn't really matter, though.

What you need to figure out is if your system is linear "enough". Stay tuned to learn how to determine this.

What does it mean to be linear?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 02 Jun 2021 19:07:08 GMT

What does it mean to have a linear system? Here are some simple rules

The frequency of the output response is the same as the frequency of the input driving mechanism
At a given frequency, the output response is related to the input response by a known ratio (for example, impedance)

Look for more the next few emails to understand why you should care if your system is linear or non-linear.

Alternate way to check boundary conditions

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 01 Jun 2021 20:23:31 GMT

Power ultrasonic transducers are applied against environmental conditions or loads in order to utilize the ultrasonic energy to accomplish the desired function.

One way to characterize the interaction of the transducer with the load/environment is to use the transducer capacitance.

When a transducer is loaded, it will more constrained - this will reduce the capacitance and this reduction can be used to characterize the extent of loading. The load won't be significant enough in all cases to cause a measurable change in capacitance, but you might be surprised as to how useful this measurement can be in your application. Try it out!

Alternate way to calibrate 10x probe

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 29 May 2021 14:17:56 GMT

The problem...

The standard method for calibrating a 10x probe is by measuring a square wave provided by the oscilloscope, and adjusting the trim-cap until all overshoot and undershoot is eliminated. This ensures the accuracy of the probe over a large bandwidth, but the accuracy at any specific frequency may have a degree of error which is unknown.

How can you address this?

Most of time, we are only interested in certain frequencies, especially for resonance devices. In that case, you can measure a sine wave signal from a function generator at the desired frequency with a 1x probe and a 10x probe. You can adjust the 10x probe's trim-cap until the two signals have the same amplitude.

Now, you have calibrated your 10x probe at the frequency of choice and you can be sure about the accuracy! This also ensures compatibility with your 10x and 1x probes as well.

You have running shoes, now what?

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 27 May 2021 19:23:20 GMT

If you have been on this list for any amount of time, you probably know that I'm not a big fan of diving right into problems without and unbiased survey of all available options and evaluation of risk.

But I do think there is a required level of inspiration necessary for any major breakthrough. I also believe that those breakthroughs don’t happen in a repeatable way; they just happen.

However, after that breakthrough, you and your team will be on a marathon to get that idea into the market in the form of a successful product from both engineering and business objectives.

Basically, after you found the perfect running shoes you should get ready to run for a long while. Don’t think you are in for a stroll.

Why should you care about the off-resonance response?

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 26 May 2021 14:16:54 GMT

Wishful thinking as a project strategy

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 25 May 2021 15:45:13 GMT

Wishful thinking is not a valid strategy for your ultrasonic transducer project.

If you do not have a plan on the course of action if your experimental results are inconclusive or disprove your hypothesis, then you have a strategy of wishful thinking.

Ultrasonic transducer project management in a nutshell

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 23 May 2021 19:18:53 GMT

Ultrasonic transducer project development is organized into three hierarchical topics:

Tactics
Tactics are the exact things engineers do during the project. These are the samples you build, the tests you run, simulations you construct, and operational aspects of a project
Objectives
The objective is the description of the goal. For example, we want to have a transducer that operates at XX performance metric with XX% yield and last for XX months of continuous operation, by XX date in the future
Strategy
The strategy is the guideline by which you decide on the tactics which will achieve the objective. For example, will you build a transducer from scratch or improve an existing design? Will you perform system testing early or after a transducer has been well defined?

Explicitly listing out your tactics, objectives, and strategy is essential for an unbiased look at your ultrasonic transducer project's potential for success.

This is all I got!

hshekhani1989@gmail.com (Husain Shekhani) — Sat, 22 May 2021 20:38:24 GMT

In the prototype stage, usually we only have a few transducers, let's say, 3 transducers. What is the best way to perform statistical analysis in this case? Just don't do it.

So, what can we learn from just a few samples? You can create specifications on critical performance parameters. That is to say, from a small sample size you can understand what you want (or don't want), but you can't determine what you will get.

The worst part is not knowing

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 21 May 2021 13:46:15 GMT

The worst part of having a small sample size is not knowing. If all of your samples have good performance, you don't know the likelihood of failure. If you have a failure, you don't know the percentage of good samples you will expect to have in the future.

Basically, low sample sizes breeds pessimism because of human nature's tendency to predict the future based off of incomplete facts.

However, many times we do not have the luxury of testing many samples, so what can we do? Don't predict the future.

Clever or Complete?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 21 May 2021 02:20:13 GMT

Let's me be honest: I have not worked on a piezoelectric/ultrasonic device where simulation of piezoelectric physics was necessary for the design of the device. But I have worked on projects where simulating the piezoelectric converse effect was a distraction.

Yes, simulating piezoelectric physics makes your simulation more complete, but it does not make it correct. Dissimilarities between experiments and simulations exist that will never be explained by linear piezoelectric constitutive equations.

If I were faced with a choice to be complete (use piezo physics simulation) or be clever (simulate what is necessary in order to get to experiments), I would always choose to be clever.

Root cause analysis starts on Day 1

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 20 May 2021 15:11:58 GMT

Your first transducer prototype will have noticeable differences from your simulations. The first root cause analysis effort of a transducer project is to understand those differences and explain them.
I don’t think it’s particularly important to get a close match between simulations to experiments. However, it is important that the differences between theory (simulations) and practice (experiments) are explained. Lack of understanding early in a project will magnify as the project continues.

The forgotten analytical parameter: the threshold

hshekhani1989@gmail.com (Husain Shekhani) — Wed, 19 May 2021 14:41:18 GMT

Threshold analysis vs. single factor analysis

When you build a bunch of transducers, you will get a variability. That’s the real world. The parameter with the most variability is often the Qm, the mechanical quality factor.

One of the major goals of measurement is to determine tolerances by which we can exclude transducers that are likely to perform poorly.

However, with regards to Qm (mechanical quality factor), we often find lower Qm transducers perform to a similar standard as higher Qm transducers. This is for transducers built with the same methods.

So, is Qm a bad metric for finding ineffective transducers? Not necessarily. In these cases, it becomes very useful to test the parameter, in this case Qm, over a variety of power levels. Then, instead of looking for a low Qm at a specific power condition to find a bad apple, we observe and document thresholds of abnormal changes.

When measurements at a certain condition can’t be correlated to other behaviors, try varying the measurement conditions (eg power levels) and looking for thresholds.

Automation, easier than ever!

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 18 May 2021 18:35:18 GMT

Digitally controlled relay boards make automation easier than ever!

Often times, only one set of expensive test equipment can be purchased. The impedance analyzer is a common piece of equipment that fits this bill (new impedance analyzer ~$30k). This creates a bottleneck in transducer testing.

In order to solve this issue, you should consider writing a script to use an Arduino to trigger a relay board. With simple wiring and some scripting, you can use the 8-channel relay board above to test 8 transducers at one time. There are also readily available 16 relay boards. You can even wire one of the relays to a test device to ensure consistency between measurements.

What would you do with the extra time you save by collecting your data 8x as fast? Testing one transducer not only takes longer, but it involves manual labor and concentration. Do the math and be good to yourself; invest a little time in automation.

Friends don't let friends....

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 18 May 2021 12:21:03 GMT

Precise frequency analysis is very important for analyzing the live performance of a control algorithm, so the jitter in the range of a few hundred hertz will not allow you to perform detailed analysis on frequency measurements. How can you achieve precise frequency measurements with a noise of <10 Hz?

As your friend, I must tell you the solution. The solution is in using FFT to measure frequency. However, using your oscilloscope's FFT capability for this will simply result in the same jitter as before. You need to improve the frequency resolution using parabolic interpolation. You need capture your waveform to your PC and then perform FFT with parabolic or Gaussian interpolation for frequency

Python and Matlab solutions are given here: https://gist.github.com/anubiann00b/97dd05df5f2082fabb53
If you use LabVIEW (like me), you can use the "extract single tone" vi to accomplish this.

Ballpark analysis is okay if you are looking to get an idea about how the transducer/control algorithm is generally behaving. However, if you are looking to upgrade from the entry level analysis, what I described in this email is essential.

The world's first piezoelectric car

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 17 May 2021 17:45:42 GMT

Have you seen the world's first piezoelectric car?

Here it is:

Yes, I believe that the we are more likely to use piezoelectric crystals as wheels than as a propulsion system. Use the right technology for the right job. Don't be hopeful working on hopeless technology.

Why 1 year?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 17 May 2021 11:46:37 GMT

Why 1 year?

In a previous email/post, I described that you should take ultrasonic transducer measurements in such a way that 1 year from today you will be able to use the data along with your additional notes and protocols and have an understanding and a level of confidence in the data as if you took the data today. AND, if you were to take the data again today, you would end up with the same measurements - that is confidence.

So why do I mention 1 year ? That is because root cause analysis can last up to one year or even more. Unfortunately, during ultrasonic transducer root cause analysis, tensions are high and answers seem just around the corner. This results in protocols, documentation, and diligence going out the window (then going SPLAT!).

Do you trust yourself?

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 17 May 2021 03:41:30 GMT

Do you trust yourself?

I'm not talking about if you trust yourself today . I mean to say, do you tr ust yourself last year ?

Basically, do you trust the measurement that you did last year at this time (May, 17, 2020)? Are your notes comprehensive enough? Did you include any safeguards against incorrect measurements? Are you sure you did fixture compensation? Were you using an obscure cable, unsure about it's quality? Was averaging enabled or not?

Data is gold, but unlike gold, it tarnishes very quickly without delicate care.

What can you do today such that you will absolutely trust, understand, and be able to confidently use your data one year from now?

Energy in an ultrasonic resonator

hshekhani1989@gmail.com (Husain Shekhani) — Tue, 27 Oct 2020 19:18:28 GMT

Energy in an ultrasonic resonator

Losses in piezoelectric/ultrasonic devices are an interesting topic both from scientific and engineering perspectives. Here, I will touch on the most important loss parameter – the mechanical quality factor.

This discussion makes some generalization for the sake of simplicity.

The root definition of the mechanical quality factor is:

Q = 2Pi (energy stored per cycle) / energy lost

Or in terms of frequency:

Q= 2Pi *f *energy stored per cycle/power loss

If we assume that the system is a first order resonator (linear-“ish”), Q can be determined from the 3db bandwidth of impedance or from the half power bandwidth considering real admittance.

The awesome thing you can do if you measure both power (with voltage, current and phase) and the Q factor using the bandwidth method is that you can back calculate the mechanical energy stored in the system

Energy stored = Q *power loss /(2 Pi* f)

However, you must measure the Q factor using a constant current sweep, which can be accomplished by providing a sufficiently large resistor in between your driver and transducer or by using a closed loop control to maintain constant current.

What’s the benefit of knowing your mechanical energy? It tells you how much energy is stored in your system, which is closely related to how much energy can be delivered per cycle. It also tells you how robust your transducer is to loading.

Please let me know if you have questions and comments on this topic at husain@ultrasonicadvisors.com. Also please send your colleagues this email and ask them to subscribe if you think they would benefit from these emails. This is the subscription link: [ Link to subscribe ]

Regards,

Husain Shekhani, PhD

Ultrasonic Advisors

husain@ultrasonicadvisors.com

Hard PZT vs. Soft PZT as an off-resonance actuator

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 23 Oct 2020 13:53:27 GMT

Hard PZT vs. Soft PZT as an off-resonance actuator

Let me ask a question. Is hard or soft PZT a better off-resonance actuator?

We all know that Soft PZT has superior d-coefficent aka piezoelectric charge coefficient. This means that a soft PZT element will exhibit more displacement for a given drive voltage( off-resonance). It will also produce more charge than hard PZT, given a specified load.

So is soft PZT better than hard PZT for off-resonance actuator applications? And if so, by how much?

Comparing a hard PZT and a soft PZT, we can find that the d coefficient is roughly twice as large. However, the d coefficient as a actuator only relates to a piezoelectric element by itself – not bonded to an external structure. Its like saying a Ferrari is fast car, but can it tow a trailer? In order to understand how much a piezo material can “tow”, you need to look at the compliance.

Hard PZT has a lower compliance (higher stiffness) than soft PZT. What this ends up meaning is that the performance gap between hard PZT and soft PZT in terms of an off-resonance actuator becomes less when considering the compliance.

This can be accomplished via d33/s33^E. For this ratio, soft PZT is only 1.6x better than hard PZT, not 2x. Please see my videos on piezoelectric actuators, blocking force, and the piezoelectric stress coefficient here: https://www.learnpiezo.com/lectures#lecture7

Regards,

Husain Shekhani, PhD

Ultrasonic Advisors

husain@ultrasonicadvisors.com

The two types of antiresonance

hshekhani1989@gmail.com (Husain Shekhani) — Mon, 19 Oct 2020 13:58:25 GMT

This is a subtitle for your new post

A colleague on my recent post on LinkedIn regarding antiresonance in piezoelectric devices call attention to the “mechanical antiresonance”.

Indeed, there are two types of antiresonances:

1. Electrical – Parallel resonance between the motional (LCR) and the capacitive current (Co). This is where current is the lowest level, i.e., the highest impedance

2. Mechanical antiresonance – frequency at which the displacement output is at a local minimum

Just like you can quickly identify the antiresonance frequency from an impedance graph (impedance peak) you can identify the mechanical antiresonance by a displacement “valley”. You can find this most easily by using an FEA program and plotting displacement of a free end vs frequency. Below you can find a plot of displacement amplitude (y axis) vs frequency (x-axis). This may look like a piezo admittance plot, but it is actually a displacement plot. The “valleys” are the mechanical antiresonance.

Displacement vs. Frequency - the valleys are the mechanical antiresonance

Frequencies where sections of your piezoelectric element or transducer are vibrating out of phase, the net displacement as seen at the end is close to zero – however, there is still vibration occurring in your structure. Mechanical antiresonances cannot be discerned from impedance analysis, because they are masked by the parallel capacitance of the other LRC branches.

Notice that the mechanical antiresonance is typically more than 20% higher than the resonance frequency. Mechanical antiresonance comes about, in on sense, by interaction of different resonance modes, thus causing maximum destructive interference at the free ends of a transducer. Electrical antiresonance is a single mode phenomenon arising from the local resonant mode and the parallel capacitance.

Please let me know if you have questions and comments on this topic at husain@ultrasonicadvisors.com . Also please send your colleagues this email and ask them to subscribe if you think they would benefit from these emails. This is the subscription link: [ Link to subscribe ]

Regards,

Husain Shekhani, PhD

Ultrasonic Advisors

Why is Antiresonance driving good and why could it be bad?

hshekhani1989@gmail.com (Husain Shekhani) — Fri, 16 Oct 2020 14:51:24 GMT

Why is Antiresonance driving good and why could it be bad?

We all understand resonance - at a certain frequency, a mechanical system oscillates, and in the case of an piezoelectric device, at a certain driving frequency we get the most bang for our buck in term of voltage input to displacement output. And, due to the direct piezoelectric effect, current is generated, which is alternating charge due to alternating stress on the piezo element.

But what about antiresonance? Many years ago, as a mechanical engineering undergrad doing piezo device research, I was completely confused about the existence of the antiresonance phenomenon. That is because for 99% of transducers, the antiresonance effect is a pure electrical phenomenon. The antiresonance can be described as the frequency where the direct piezo effect is creating current at an opposite phase to the intrinsic capacitance of the transducer. That means mechanically generated current is canceling with capacitive current, thus making the current draw of the transducer very small giving it a high impedance.

Is high voltage drive really that bad?

Piezoelectric devices are voltage driven, and thus there is no “displacement peak” at the antiresonance frequency. Actually, if you were to hold voltage amplitude at a precise level, you would not find any distinguishing feature from a displacement vs frequency response at the antiresonance frequency.

If the displacement is smaller at anti-resonance in comparison to the resonance frequency, why would we use anti-resonance at all? Most commonly, ultrasonic welding equipment uses anti-resonance, so why should those applications use antiresonance if it takes more voltage to drive the transducer to the desired mechanical output.

The last paragraph was “charged” with an assumption (no pun intended). The assumption is that high voltage is not desirable. The four universal reasons why high voltage (500V+) is undesirable is

(1) Dielectric heating

(2) Increasing the potential for arcing

(3) Safety risk

(4) Risk depoling ceramic if negative voltage is applied.

These problems can be combated by:

(1) Dielectric heating can be combated by using hard PZT (low dielectric loss)

(2) Good mechanical and acoustic design, conformal coating, applying insulation, and increasing the number of piezo elements can decrease the likelihood of arcing

(3) For non-consumer applications, proper grounding can ensure user safety

(4) A positive DC bias can provide relieve from negative voltage

Why is antiresonance a good thing?

We just discussed why antiresonance and it’s necessity of using a large voltage in actuator applications is not necessarily a bad thing. But why is it a good thing? What benefits does antiresonance driving provide?

Antiresonance presents a high electrical impedance to the electrical driver. When a transducer is loaded, the antiresonance impedance drops –voltage delivered to the piezo is still constant because the impedance is still high (although lower than before) the amount of power delivered increases. Going back to Ohms law, V=IR, the R drops, and therefore the current and hence power delivered to the transducer increases. What is happening is that the transducer output power is self-regulating without the need for a high-performance feedback circuit. When the transducer is loaded, more power is instantaneously required to maintain the oscillation amplitude -hence, using the anti-resonance frequency drive promotes an analog method of adjusting power according to the load presented to the transducer.

Antiresonance drive can also be thought of as oscillation amplitude correlating directly with voltage, whereas at resonance the oscillation amplitude correlates to current. Because electrical driving circuits operate on a controlled output voltage level scheme, and not constant current, utilizing antiresonance makes the electronics and control algorithm simpler.

A proper transformer is all you need to efficiently step up your low voltage driver to become an antiresonance driver. If your application requires a lightweight electrical driver, this method may not be possible because transformers are large in comparison to other electronic components.

Please reach out if you have comments and questions on this article ( husain@ultrasonicadvisors.com ). I’d love to hear from you.

Impedance Frequency Response of a Piezoelectric Element Using COMSOL

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 30 Jul 2020 11:57:14 GMT

Impedance Frequency Response of a Piezoelectric Element Using COMSOL

***I provide ultrasonic transducer simulation services for product development. Please learn more about my consulting here: https://www.ultrasonicadvisors.com/ ***

In this article, we are going to demonstrate the electrical/impedance frequency response of a piezoelectric element using COMSOL. We will perform this using a 2D simulation. We will also be discussing phasor theory, how to use relevant expressions in COMSOL, apply boundary conditions, and how to determine and plot the impedance and the phase .

SETTING UP THE SIMULATION

To start, go to COMSOL -> WIZARD -> STRUCTRURAL MECHANICS -> PIEZO. Next, Go to STUDY and select FREQUENCY RESPONSE.

After setting this up, Select Rectangle as the Geometry.

Change the unit to millimeters, and then create a rectangle with Width = 40mm and Height = 1 mm.

Select PZT-4 as the material.

Under Solid Mechanics, set the thickness of the material to 0.005 m.

The thickness here is the out-of-plane thickness of the sample which is important for the mechanical response of the material. Although you won’t get stress distribution in that domain, it has effects on other parameters.

Under Linear Elastic Material, Select Damping.

Select Isotropic as the Solid Model.

Set the Isotropic Loss Factor of the material which relates to the Quality Factor (Q) of the material.

Assuming a Quality Factor Q = 500. Using this , we have the Equation:

Using the value Q = 500, we have:

Ideally, we should set the Isotropic Loss Factor on COMSOL to the computed value 0.001, as that is close to the value for PZT-4. However, in this simulation, to be able to witness the effect of damping better, we will use a value of n = 0.01 instead. This translates to a Quality Factor Q = 50. A more typical representation of our software PZT such as PZT-5.

Specify the bottom of the plate as Ground.

Specify the top of the plate as having Electric Potential.

Set the Electric Potential to 1 Volt.

Apply Boundary Probe by going under Definition -> Probes -> Boundary Probe.

After creating Boundary Probe, select the top of the plate as the boundary.

Notice the unit of our expression, Charge per meter (C/m) .

In case we have a 3D simulation, this unit will be Charge per square meter (C/m^2) because that would be the electrode and the electrode is in 1D, therefore we have to integrate over that electrode.

To be able to do this in COMSOL, select Integration as the Method and set the probe type as integral.

Normally, with a two dimensional electrode we use the formula :

However, in our case, since the electrode is defined one dimension, we only have:

Based from our new equation, it means that we can already integrate the width by multiplying it.

To reflect this on our COMSOL simulation, we multiply the expression with our set width which as defined earlier is 0.005 m.

At this point, we already know the total charge of the material. However, in most cases, we are more interested in the current.

Using the equation of charge with respect to time,

And since we know that the derivative of charge is equal to the current, we have the equation:

Simplifying the equation:

From the equation we can see that

To reflect this to our COMSOL simulation, we should also multiply our expression by the angular frequency. Also to make sure that we get the units right, we will also specify the units in our expression.

Under Frequency Domain, Set the Frequency Range Step to 1000.

Now we have already finished setting up, we can now run the simulation by going to Study and press Compute.

ANALYZING SIMULATION RESULTS

In order to view the impedance and current response, select Probe Plot in the results.

The figure shows the current response with respect to frequency.

We have both negative and positive current. We also have imaginary current which this is due to the fact that we have positive and negative phase. Only the real part of the current is being plotted here, however we need to plot amplitude and in order to plot amplitude we need to calculate the absolute value.

To do that in COMSOL, under Results create 1D Plot Group.

Under 1D Plot Group, create Point Graph.

Set the Point Graph to Active and select a Point on the boundary we previously measured.

Type the corresponding expression for impedance.

We also need an expression to calculate phase.

Using the diagram above, we have the Equation:

Converting the phase angle in degree we multiply the right side of the equation with the conversion factor:

It must also be noted that Impedance (Z) is inversely proportional to Current (I) .

And basically, bnd1 is proportional to the current.

That being said, we can also write the equation of phase in terms of current so we have:

Reflect the corresponding equation in COMSOL expression.

Plot the graph.

On the graph, we can see that the resonance and anti-resonance frequency is plotted on the negative side.

To compensate that, we simply negate our expression and plot again.

So basically that’s it, we are now able to show the electrical frequency response of a piezoelectric element using COMSOL. By including a finer frequency interval, we will be able to see the gradual change in phase and impedance around the resonance and antiresonance frequency.

If you need help with simulation of your ultrasonic device in COMSOL or any other FEA package, please set up a free consultation with me at calendly.com/ultrasonicadvisors/30min or by emailing me at husain@ultrasonicadvisor.com

I advise to students and industry professional alike. Many of these discussions have resulted in full projects with Ultrasonic Advisors.

COMSOL Simulation of the Direct Piezoelectric Effect

hshekhani1989@gmail.com (Husain Shekhani) — Thu, 09 Jul 2020 18:14:26 GMT

COMSOL Simulation of the Direct Piezoelectric Effect

***I provide ultrasonic transducer simulation services for product development. Please learn more about my consulting here: https://www.ultrasonicadvisors.com/ ***

In this article, we are going to demonstrate the simulation of direct piezoelectric effect by using a FEA simulation program known as COMSOL. We will apply force to a piezoelectric element and from that force the piezoelectric element will produce voltage.

Equations Describing the Direct Piezoelectric Effect

We will start with two equations. First is the piezoelectric equation, the relationship between polarization and stress:

The second equation is the electrostatic equation of a capacitor:

These two equations are important in understanding how an applied stress/force relates to a charge developed and will serve as the basis of our derivation. Since polarization (P) is essentially charge per area we have:

Also, since stress (X) is force per area we have:

Substituting Equation iii and iv to Equation i we have:

Simplifying the equation, we get:

With this equation, we can conclude that if we have a piezoelectric material and we apply a force to that material over a small area or a large area, we will get the same voltage – this is because the force is the area integral of applied stress.

However, in sensor applications, we typically measure voltage. There, we need to further derive to get an equation with respect to voltage.

Substituting equation ii to Equation v we have:

Simplifying the equation, we get:

The capacitance here is determined by the permittivity of the material under free stress. So, we have the capacitance of the material using the formula:

Substituting Equation vii to Equation vi we have our working equation in terms of voltage as:

Based from the derived equation, we can say that as the area of the piezoelectric material increases, the voltage decreases.

Setting Up a Static Simulation in COMSOL Describing the Direct Piezoelectric Effect

Now let’s witness the direct piezoelectric effect by designing a simple cylinder in COMSOL and applying force and measuring voltage.

Firstly, we will go to model wizard in COMSOL. In our case select 3D then go to structural mechanics and select piezoelectric devices and add necessary physics for this simulation. We want to look at stationary results because we are doing a static simulation, so add stationary physics.

Change meters to millimeters because that’s primarily the scale we work in for piezoelectric devices.

In order to add the piezoelectric element geometry, go to the geometry panel and build a cylinder.

Set the cylinder radius and height 10mm and select Build All Objects.

From the materials options, assign the PZT material by going to library and select PZT-4 which is the standard PZT.

Select Fixed Constraint in the Solid Mechanics to fix the material at the bottom.

In order to apply force, under Solid Mechanics go to Boundary Load. Select Total Force as the Load Type and apply -10N to z-axis.

In order to measure voltage potential across the piezoelectric material, it is very important to note that when doing this in COMSOL, we need to specify one of the electrodes as "floating" and one as "ground".

Select Add Study and Select Stationary.

Under Definition, go to Probes, select Boundary Point Probe and specify the top of the piezoelectric material.

Under Point Probe Expression, specify Floating Potential.

With all parameters set, we can now start the simulation by going to “Study” and clicking “Compute”.

Comparing Simulation Results

In order to find the voltage measurement, select Probe Plot in the Results. Here we can easily see that the floating potential is -7.58 V.

To verify our simulation, we will use our previously derived equation to solve the voltage and compare it with the value from our COMSOL simulation.

Using the formula, we substitute our values used in the simulation

Substituting the values to the equation we get:

As we can see, there is a slight variation between our computed value and the value given by the COMSOL simulation. That difference is due to the constraint we put in the COMSOL simulation. When we constrained the bottom portion of the piezoelectric material, the material cannot get larger at the bottom as the force is applied. Nevertheless, we are able to verify that our simulation is correct.

Here are some important relationships, assuming we increase one variable, keep constant another, and the following result:

COMSOL Tutorial - Converse Piezoelectric Effect

hshekhani1989@gmail.com (Husain Shekhani) — Sun, 07 Jun 2020 04:04:37 GMT

***I provide ultrasonic transducer simulation services for product development. Please learn more about my consulting here: https://www.ultrasonicadvisors.com/ ****

In this article, we are going to demonstrate the simulation of the converse piezoelectric effect by using a FEA simulation program known as COMSOL. We will apply voltage to a piezoelectric element and from that voltage the piezoelectric element will produce strain, or we can also say displacement.

Equations Describing the Converse Piezoelectric Effect

Figure 1: Piezoelectric Element

In order to determine the strain, and hence, displacement, we multiply the electric field E_3 by the piezoelectric constant d33. d33 is measured for strain in same direction as the spontaneous polarization and this property is measured under constant stress which means that there are free-stress boundary conditions on all of the adjacent sides of the piezoelectric element in question.

Along the polarization direction, x_3 , $x_{3}$ is the strain, d_33 is the piezoelectric charge constant, and E _3 s the electric field.

x_3 = d_33 * E_3

We know that the strain is the change in the length over the total length. In this case, thickness is actually the length

x_3 = delta t / t

$x_{3} = \frac{Δ t}{t}$

The electric field is the voltage per length (thickness) i.e.

E_3 = V_3/t

Resolving, Equations (2) and (3) in to Equation (1) we have

delta t / t = d_33 * V_3 / t

After cancellation of thickness from both sides we will get

delta t = d_33 * V_3

And also "delta t" is the change in thickness, which is also the displacement. Note how the actual thickness does not change the amount of displacement.

Setting up a Static Simulation in COMSOL for the Converse Piezoelectric Effect

Now let’s witness electric field induced strain (converse piezoelectric effect) by designing a simple rectangular block in COMSOL and applying voltage.

Firstly, we will go to model wizard in COMSOL.

In our case select 3D then go to structural mechanics and select piezoelectric devices and add necessary physics for this simulation. We want to look at stationary results because we are doing a static simulation, so add stationary physics.

Change meters to millimetres because that’s primarily the scale we work in for piezoelectric devices.

In order to add the piezoelectric element geometry, go to the geometry panel and open your work plane and build a circle of radius 10mm at coordinates (0,0).

Then draw another circle of radius 0.2mm in the center and select build all.

After that extrude the larger circle and we will get our final piezoelectric disk as shown in figure. The smaller circle will be used to add a fully contrained mechanical boundary condition which has a low impact on the final simuation, because all static simulation must have a fixed boundary as a reference. An important note here is that if we were to full constrain the entire face, the element would undergo resistance to stretching in the thickness due to the poissons ratio lateral contraction expansion that happens in tandem with extension in the thickness direction, which is the main effect and the effect we will be looking at in this simulation. If you do fully constrain the entire face, you will get less displacement (but not zero) and you will not be able to validate the equation of $d_{33}$ .

From the materials options, select the PZT-4 and add that in model.

We will now need to add boundary conditions. We added a small circle in the model so that we can add a fixed constraint reference. Add this condition that part by selecting Fixed Constraint in the Solid Mechanics.

In order to apply voltage, go to Electrostatic and apply voltage boundary conditions on the opposing faces of the disk. We have to apply a voltage boundary condition on the bottom as well. Assign an Electric Potential boundary condition on the top face of the disk and Ground to the bottom.

Now go to the Piezoelectric Materials setting and change to “Strain-charge form” because this form of describing the piezoelectric effect allows us to use the piezoelectric charge coefficient d33 . The alternative standard setting is to use the piezoelectric stress coefficient e33 which is not directly calculated from any standard experimental measurement methods. It’s is derived from measuring multiple anisotropic properties and matrix calculations; however, the piezoelectric charge coefficient can be readily determined from laboratory equipment, especially from a d33 meter.

Change the piezoelectric coefficient value to 289 E-12, whose units are Coulombs/meter.

To more easily view the model, you can just change the extrusion distance. I changed it to 10mm here. Now, build the mesh.

Compare Simulation Results (Displacement) to Equations

Then go to Study and Compute and go to the 2D plot Group 3. By looking at the scale from the figure, we determine the total displacement. The maximum displacement is little more than 3 E-7 mm, which is 3 nanometers.

We can clearly see the displacement varying dominantly in the thickness direction, and a slight variation along with width effect due the fixed boundary constrain we needed to put in order to allow the model to solve. When we apply an electric field to a piezoelectric material it expands to a zero stress condition. So, although there is no stress, there is displacement.

We can understand this from an analogy to thermal expansion. For example if we heat a material, it expands but when the material expands it’s not under stress. Internal stress is actually causing to expand. Once expansion is finished there is no more internal stress. However you will clamp it anyway you will develop stress. There it is correct that there is no stress involved here. If we did not allow the material to expand then it would be under external stress. Basically, applying an electric field resets the equilibrium dimensions of the piezoelectric material, after which the material deforms to reach that equilibrium zero stress state.

In order to find the exact displacement, make a probe by selecting definitions in Component 1 and finally Domain Point Probe in probes. Run the simulation again to get the solution. Select Probe Point 4 in results. Here we can easily see that it’s 2.9E-7mm. Therefore,

delta t = 2.9 E-7 mm = 2.9 E-9 m

As we applied electric potential of 1V, d33 calculated from the simulation via the electric field and the strain

d33 = E_3 / x_3 = 290E-12 C/N

We can check the coefficient value that we got by simulation simply by going to material properties again. Here we can see that it is 2.89 E-12, exactly what we put in for the d33 e arlier

In microns the measurement will be 2.9e-4 $2.9 \times 10^{- 4}$ μm, very small!. Because the displacement generated by the converse piezoelectric is very small, we use resonance, large voltages, and multi-layer structures to increase the displacement

High Power Characterization of Ultrasonic Transducers - Four Methods You Need to Know About

Mon, 03 Feb 2020 15:54:56 GMT

The need for high power measurements is real

The tool you are using to characterize ultrasonic transducers is the impedance analyzer (or network analyzer). However, the excitation power of this piece of test equipment is on the order of mW, while power ultrasonic transducers operate from 1W to 100W, and even upwards of 1kW for some applications.

Non-linearity both at the microscopic (eg material properties) and macroscopic level (eg component interaction) cause drastic differences between impedance analyzer testing and high power performance - for example, the mechanical quality factor and impedance can increase by an order of magnitude from lower power and high power characterization. This can result in approving transducers who exhibit good characteristics under manufacturing impedance analyzer tests, but fall extremely short when they are put to test in a real application.

Luckily, there are four ways to increase your confidence in the performance and reliability of your transducers by determining their high power performance. Don't let an unhappy customer be your final testing platform!

Four methods to determine the high power performance of your transducer

Use the actual application/driving system
Use an impedance analyzer with a power amplifier
Use custom scripting program with an oscilloscope and function generator
Use a USB oscilloscope, with advanced spectrum analysis capabilities

Method 1: Use a version of the actual application to characterize the transducer

Let's take an ultrasonic cleaning transducer as an example. The goal is to ensure the transducer will deliver adequate acoustic power to the cleaning chamber. You can verify this using a test device's drive electronics, which delivers a certain voltage to the transducer at the specified frequency. The transducer's power consumption is monitored and recorded via an external oscilloscope. If the power delivered is too high or too low, then the transducer would be considered out-of-tolerance.

Pros +

If the transducer under test works as expected in the test device system, then it is a great indication that it will work as intended as a system component in the final assembled system
You have all the supplies needed in-house to create the test setup

Cons -

In this method, part to part variation will be assessed from a system level, therefore, using this method will increase variability in the measured transducer characteristics. My experience has shown up to a 100% increase in variability when using a test device to evaluate the characteristics of a transducer
The test setup will have issues with reproducible, as the device electronics and firmware used for drive is not designed for accurate characterization
Each transducer in a company's offering may need a different testing setup
The test method may not readily provide necessary information about the transducer, such as resonance frequency and resonance impedance

Method 2: Adapt the impedance analyzer to work with a power amplifier

In this method, an impedance analyzer's measurement and signal connections can be hooked up to a power amplifier. An impedance analyzer has four terminals: H-CUR, H-POT, Low-CUR, L-POT. Connecting these terminals according to the figure below will allow you to drive your DUT with high power, while relying on the impedance analyzer for measurement and display.

Figure: How to use an impedance analyzer for high voltage measurements (Figure 5-44 of Agilent's Impedance Analysis Handbook ).

Pros +

Impedance analyzers are common (but expensive), so you already have the basic equipment and parts needed to accomplish the measurement
A full frequency sweep can be performed and the data output (impedance) will be presented to the user in a similar manner to the normal (low power) operation of the impedance analyzer.
Accurate measurements are possible

Cons -

Post-processing of impedance data may be necessary
Using a high power amplifier in-line with your impedance analyzer may put the impedance analyzer at risk for electrical damage. Tip: Make sure you have insurance on your impedance analyzer before attempting to hook up a power amplifier.
Excitation levels, compensation circuitry, and measurement circuitry must be carefully chosen for the specific transducer and excitation level. Changes in frequency, excitation levels, or transducers may require significant changes to the test setup

Method 3: Programming an Oscilloscope with Signal Generator

A signal generator and oscilloscope controlled via a computer scripting language such as Python, C#, or LabVIEW can be use to capture the frequency response of an ultrasonic transducer. The program will incrementally sweep the frequency across the desired band, during which the oscilloscope's measurements will be read by the computer program. Because this method uses a computer program, the user has full control on how the application functions. During my academic work, I've worked on a LabVIEW application which uses closed loop control of either voltage, current, power, or measured vibration during the frequency sweep to make for some very insightful measurements ( link to research article ).

Custom computer program controls an oscilloscope and function generator to measure frequency response of a ultrasonic transduce r ( my dissertation pg 68 )

Pros +

System is flexible, and can be altered according to the needs of varying types of transducers

Closed loop control can be used to fix parameters such as output voltage, which would otherwise decrease at resonance due to the drop in impedance of the DUT

Uses an oscilloscope and function generator, which are very common and versatile instruments

Cons -

Custom programming is required

Method 4: USB oscilloscope (Picoscope) with power amplifier

A USB oscilloscope ( specifically, a Picoscope from Pico Technologies ), has a unique function in it's spectrum analyzer, It can hold the peak detected value over a frequency sweep. Therefore, it can record the frequency response of voltage and current at a DUT during a frequency sweep, to give important impedance response data. The USB oscilloscope has an AWG built-in which should be used with a power amplifier for high power excitation of your transducer. The USB oscilloscopes can be very inexpensive and still have sufficient bandwidth to handle <100kHz signals. Take a look at Picoscope 2204a)

Voltage (blue) and Current (red) vs. Frequency from Picoscope desktop program. Minimum voltage signifies the DUT's lowest impedance, which is the resonance frequency

Pros +

Does not require special circuitry and is robust to over-voltage, as current does not sink into the test equipment. Additionally, running off of a laptop, the Picoscope becomes a floating scope.
Does not require any programming or custom software

Cons -

The frequency resolution is limited based on the sampling scheme supported by the hardware
Optimal program settings have to be determined, especially with respect to the FFT sampling and binning settings
The frequency resolution is limited based on the sampling scheme supported by the hardware

The winners according to price, repeatiblity, and value of the collected data

High power characterization is a must have for any manufacturing or R&D operation of ultrasonic transducers. Between all of these methods, here are my winners according to price, repeatibility, and value of the data:

Price of the test setup

Method 4: Hands down, the Picoscope provides the most inexpensive option, while producing highly relevant measurements. The fact that a standard program can be used to administer testing is a huge thumbs up

Repeatiblity of the measurement

Method 2 (Impedance analyzer) and Method 3 (programmed oscilloscope and function generator) provide the most repeatable measurements. That being said, Method 1 gets a good rating in this category because of the accuracy of the impedance analyzer and Method 3 gets a good rating in this category because of its ability to provide closed loop control of voltage (or another chosen output parameter)

Value of the data

This is a tricky one. Method 2 (use of actual device/driving system) is apparently the best in this category because it is closest to the real driving conditions. That being said, it suffers from being a non-standard test method and is subject to system variation. Therefore, I suggest the best option is to use Method 2, 3, or 4, for characterization, and Method 1 for ensuring system level compatibility

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Resources:

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Beyond PZT: Navigating the Transition to Lead-Free Piezoceramics — Featuring Expert Insights from PI Ceramic

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The Science Behind Piezoelectric Materials

Practical Applications and Limitations ﻿

Medical Applications ﻿

Industrial Applications

Consumer Electronics Integration

Piezoelectric vs Electromagnetic Devices: A Comparison

Design Considerations and Engineering Challenges

Future Trends and Innovations

System Integration and Control

Conclusion

Future Trends in Ultrasonic Technology

When to Seek Expert Help

Power Ultrasonic Transducer Design Guide: From Theory to Implementation

What Are Power Ultrasonic Transducers?

Why Companies Choose Ultrasonic Technology

Understanding the Core Components ﻿

The Central Bolt: More Than Just a Fastener

Back Mass: The Hidden Performance Driver

The Horn: Where Theory Meets Practice

Common Design Challenges and Solutions

Crystal Stack Design ﻿

Managing Stress Distribution

The Assembly Process: Where Success Is Made or Lost

Preparation Is Everything

The Critical Preload Step ﻿

Testing and Validation

Beyond Basic Measurements ﻿

Future Trends in Ultrasonic Technology

When to Seek Expert Help

Conclusion

Free Ultrasonic Modal Analysis/Resonance Simulation Software/FEA

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" How to calculate the equivalent circuit for an ultrasonic transducer from impedance "

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