PVDF membrane hydrophone performance properties and their relevance to the measurement of the acoustic output of medical ultrasonic equipment

Three basic types of membrane hydrophone made from the piezoelectric polymer polyvinylidene fluoride (PVDF) are described. These have been developed as instruments for the characterisation of ultrasonic fields in the megahertz frequency range. Performance properties such as sensitivity, directional response, membrane reflection, linearity and signal-to-noise ratio are considered for various devices made from films of thicknesses between 0.006 mm and 0.080 mm and with active elements from 0.5 mm to 4 mm diameter.