Simulation Study of Mems Piezoelectric Hydrophone Based on Flexible Substrate

In this paper, three types of AlN film-based piezoelectric hydrophones with the rigid, quasi flexible, and flexible substrates are designed and the performance of them are optimized by using 3D-FEM in COMSOL simulation software. In addition, a systematically investigation is performed to assess the impact of the silicon layer thickness, PI layer thickness and cavity radius on the receiving sensitivity and resonance frequency of the hydrophones. Simulation results show that the receiving sensitivity level of the flexible hydrophone with PI substrate is 7.18 dB higher than that of the rigid hydrophone based on Si substrate, and the receiving performance is improved by 129.0%. In addition, the resonant frequency of the flexible piezoelectric hydrophone is 39.7 kHz, and the resonant frequency of the rigid piezoelectric hydrophone is 40.2 kHz, which is further reduced by 0.5 kHz. Therefore, the ability to pick up low-frequency sound signals underwater is enhanced. These results can provide constructive guidance for improving the performance of flexible hydrophones.