Design of the Monolithic Integrated Array MEMS Hydrophone

Abstract

Since the sensitivity and frequency band of the micro-electro-mechanical system (MEMS) bionic vector hydrophone restrain each other, a single hydrophone can not simultaneously meet the high sensitivity and wide frequency band requirements. Therefore, in this paper, based on a single MEMS bionic vector hydrophone, a $2\times 2$ four-unit array microstructure on a chip has been proposed to realize both high sensitivity and wide frequency band, which consists of four four-beam-cilium structures with different cilium lengths of 10000, 8000, 6000, and 3000 $\mu {\mathrm{ m}}$ , respectively. The array structure sizes are determined by the theoretical and simulation analysis, and then the array structure is fabricated integrally by the MEMS manufacturing technology. Finally, this paper presents the experimental characterization of the packaged array hydrophone in a standing wave tube to validate the theory and the simulation. The test results show that the array hydrophone has high sensitivity and good frequency response, exhibiting the highest sensitivity of −189 dB (without pre-amplifier, 0 dB reference 1 V/uPa) and frequency band of 20–5000 Hz, both bearing witness to a good directivity in the shape of 8. The improvements of the hydrophone performance broaden its application scope.