Recent measurements on improved thick film piezoelectric pvdf polymer materials for hydrophone applications

A broad outline is given of THORN EMI Central Research Laboratories’work in converting PVdF materials into sensitive hydrostatic-mode hydrophone elements. Emphasis is placed on the piezoelectric coefficients and voltage sensitivities obtained. Some data is also presented on ageing characteristics at normal ambient and elevated temperatures and for repeated pressure cycling between ambient and high pressures (∼20 MPa). Hydrostatic-mode hydrophone sensitivities of -195 dB rel 1VμPa−1 are reported for 630μ thickness highly voided PVdF which greatly surpasses the typical -205 dB rel 1VμPa−1 for natural draw ratio material calculated at the same thickness.