How to Build an Ultrasound Characterization System
If you are developing an ultrasonic device, at some point you need to know what the acoustic output of your ultrasonic device is. Whether it is for internal R&D testing, design verification and validation (DV&V), or for submission to a regulatory body (FDA, EMA, PMDA, etc), understanding the acoustic field of your device is critical for building safe, effective products. In this guide we review the basics of what you need to build your own ultrasound characterization system, and how our services can get you up and running quickly and with confidence.
1) Identify what ultrasonic measurement standards apply for your ultrasound device. All ultrasound characterization systems need to follow IEC 62127. If you have a technology that’s well established, you will also need to apply any device specific measurement and safety standards as well to your methods.
2) Purchase the right equipment. For all systems, you need the following basic equipment:
Hydrophone. For 90% of applications, we recommend getting a needle hydrophone. Needle hydrophones are cost effective, easy to use, robust, and with the latest signal processing guidance from IEC 62127 you can compensate for any potential spatial averaging effects or non-uniform frequency responses of the hydrophone. If your ultrasound device has a fundamental frequency between 100kHz - 20MHz and expected peak pressures of up to 10MPa, go for a needle hydrophone. If your device will likely greatly exceed 10MPa, and you're okay with a 0.5MPa noise floor, you might consider the fiber optic hydrophone from Onda. If you plan to take measurements not in a water bath but would meet the criteria for a needle hydrophone, you might consider the fiber optic hydrophone from Precision Acoustics. But, even if you have high outputs or non-conventional setups, there are lots of creative techniques for using a needle hydrophone for those contexts (which is what I generally recommend for all our customers). Fiber optic hydrophones are hard to use and are very expensive, but sometimes it’s what makes sense for a few applications. Our team is happy to work with you to understand your specific needs and provide a recommendation on hydrophone selection.
Oscilloscope. Any modern oscilloscope with a minimum 250MHz bandwidth should work for an ultrasound data acquisition system. I recommend at least 2 channels, but you may want up to 4 if you are also measuring other non-acoustic parameters of your device.
Motion stage, hydrophone fixture, device fixture, water bath. The rest of the equipment is pretty basic and straight forward. You need a motion stage to position your hydrophone, a fixture to hold your hydrophone and you device, and a water tank to take your measurements.
Water conditioner. In general, hydrophones are designed to take measurements in water (hydro = water, phone = sound). You generally want to use distilled, deionized, degassed water which is where a water conditioner can be helpful. Do I always condition my water? Depends on the types of measurements I’m doing. But, make sure your water is clean and no visible bubbles at minimum. When in doubt, clean your tank and put in fresh water, you’ll be surprised how often that solves weird measurement issues.
3) Signal Processing Algorithm. Once you’ve designed a system that acquires data per IEC 62127, you will need signal processing algorithms that generate the relevant acoustic output parameters based on the relevant ultrasound measurement and safety standards you have identified for your application. IEC standards change over time, so it is important to ensure your algorithms stay up to date to maintain compliance (particularly if these data are used for a regulatory submission).
If you already have an oscilloscope and hydrophone, our team will work with you to automate your existing equipment and ensure your data are being processed in accordance to latest international guidance. There’s a lot to consider when building an ultrasound characterization system. When you work with us, we start with a detailed client intake session to ensure the ultrasound characterization system meets your specifications and will be compatible with your hydrophone and oscilloscope. We then send you the blueprints to build your own validation ready data acquisition system and the software needed to acquire and process your data based on international standards.
At Bay Area Sonic Solutions, we believe ultrasound measurements and regulatory compliance should be the easiest part of your device development journey. Contact us today to see how we can automate your workflows and bring confidence to your ultrasound measurements. Happy building!
