PVDF sensor design and FPGA implementation of ultrasound power measurement

Ultrasound devices provide either diagnostic or therapeutic purpose in biomedical application. To avoid unwanted power exposure to the patient for safety concern but at the same time maintaining optimum diagnostic and therapeutic effect, ultrasound power meter is used to measure and calibrate the output power and intensity of the ultrasound machine. Most of the current ultrasound power meters are limited for either high power therapeutic or low power diagnostic purposes but not both and it is expensive. To enable Polyvinylidene fluoride (PVDF) for low cost ultrasound power meter, a robust low cost casing has been designed for optimum ultrasound power capturing from both therapeutic and diagnostic ultrasound machine. The system has been designed to minimize interference effect and noise, as well as to stabilize mechanical construction of the sensor. This paper presents a PVDF sensor design of an ultrasound power measurement system that is compact and simple in construction, easy and user friendly, but at the same time provides a reliable power measurement result. The power meter is designed using PVDF sensor and Altera Cyclone II Field Programmable Gate Array (FPGA) technology. Results show that this in-house power measurement system is able to measure 0.5 MHz - 10 MHz of the frequency range and 1 mW/cm² to 10 W/cm² of the intensity range.