<title>Solid state MOSFET-based hydrophone</title>

Abstract

In this paper, we present the design and fabrication of MEMS hydrophones on a silicon wafer using standard NMOS process technology. The effects of two MOSFET amplifiers with different W/L ratios on the hydrophone performance are investigated. A piezoelectric polymer, polyvinylidene difluoride, is employed as the sensing material. Acoustic impedance possessed by this piezoelectric material provides a reasonable match to that of water, which makes it very attractive for underwater applications. Measurements of the hydrophone devices were carried out in a pulse tube with a frequency range of 4-10 KHz. The results reveal that the hydrophone comprising a MOSFET with larger W/L ratio provides better sensitivity.