Research on the Nested Package Structure of a MEMS Vector Hydrophone

The main frequency band of the radiated signals from ships is 20–500 Hz and also the main working frequency band of the micro-electromechanical systems (MEMS) vector hydrophone. To improve sensitivity in this frequency band, this article presents a nested package structure, which encapsulates the sensitive sections of the vector hydrophone with a mesh-like interior support and a sound-transparent cap. By COMSOL Multiphysics 6.0 simulation, the particle acceleration and intrinsic frequency of the hydrophone with different interior supports and sound-transparent cap are compared and analyzed. The simulation results show that the hydrophone encapsulated with nylon interior support and latex acoustic cap has higher acceleration, and its intrinsic frequency is 2285.1 Hz in air and 804.64 Hz underwater. The results of the testing indicate that the nested package hydrophone designed in this article has a bandwidth of 10–800 Hz, meeting the main working frequency band of the hydrophone. Additionally, the sensitivity of the hydrophone with latex encapsulation is increased by 7.8 dB at 100 Hz than polyurethane encapsulation. The depth of the notch at 100 and 500 Hz is more than 30 dB, which indicates that the hydrophone has good dipole directivity. Compared with the traditional polyurethane-packaged hydrophone, the nested package structure can effectively improve the performance of the hydrophone.