3B-3 Calibration of PVDF Hydrophones Using a Broad Focus Electromagnetic Lithotripter

Correct measurement of acoustic pressure is crucial in many applications, e.g. medical diagnostics and therapy, where the physical effect of ultrasound on tissue depends on specific parameters of the wave, such as positive and negative pressure, shock front thickness, and pulse duration. In our previous paper, we reported building a new low-cost PVDF hydrophone to detect broadband signals from lithotripters and high intensity focused ultrasound (HIFU) sources. The hydrophone was built to complement the fiber optic probe hydrophone (FOPH), which has become the de facto standard broadband hydrophone for high amplitude medical devices. Our PVDF membrane hydrophone is more sensitive than the FOPH, thereby making measurement possible when averaging is not an option. The goal of this research was to develop a reliable method of calibration by comparing the PVDF hydrophone to the FOPH in a repeatable broadband pressure field. The results showed that the PVDF membranes had similar, though not identical responses.