Unclosed Hexagonal Piezoelectric MEMS Hydrophone Based on Rigid-Flexible Composite Membrane

In this paper, a piezoelectric microelectromechanical system (MEMS) hydrophone based on rigid-flexible composite membrane of unclosed hexagonal beam is reported. This rigid-flexible composite membrane is the vibrating membrane of hydrophone, which is composed of rigid silicon-on-insulator (SOI) and flexible 3μm thick Parylene C. The structural design of this hexagonal beam vibration sound transmission unit and the unique interaction mechanism of rigid-flexible composite show extremely high sensitivity in a specific frequency band, and -161 dB@1.6 kHz. The high sensitivity displayed at low frequency bands and specific frequencies indicates the important potential of this MEMS hydrophone in underwater monitoring, signal transmission, ocean affairs and so on.