High-Sensitivity Piezoelectric MEMS Accelerometer for Vector Hydrophones

Abstract

In response to the growing demand for high-sensitivity accelerometers in vector hydrophones, a piezoelectric MEMS accelerometer (PMA) was proposed, which has a four-cantilever beam integrated inertial mass unit structure, with the advantages of being lightweight and highly sensitive. A theoretical energy harvesting model was established for the piezoelectric cantilever beam, and the geometric dimensions and structure of the microdevice were optimized to meet the vibration pickup conditions. The sol-gel and annealing technology was employed to prepare high-quality PZT thin films on silicon substrate, and accelerometer microdevices were manufactured by using MEMS technology. Furthermore, the MEMS accelerometer was packaged for testing on a vibration measuring platform. Test results show that the PMA has a resonant frequency of 2300 Hz. In addition, there is a good linear relationship between the input acceleration and the output voltage, with V = 8.412a − 0.212. The PMA not only has high sensitivity, but also has outstanding anti-interference ability. The accelerometer structure was integrated into a vector hydrophone for testing in a calibration system. The results show that the piezoelectric vector hydrophone (PVH) has a sensitivity of –178.99 dB@1000 Hz (0 dB = 1 V/μPa) and a bandwidth of 20~1100 Hz. Meanwhile, it exhibits a good “8” shape directivity and consistency of each channel. These results demonstrate that the piezoelectric MEMS accelerometer has excellent capabilities suitable for use in vector hydrophones.

MEMS flexible conformal hydrophone based on heterogeneous integration technology

“…The second research direction has made material innovation in the first research direction, replacing traditional accelerometers with accelerometers made of piezoelectric thin films. At the same time, through material updates, some shortcomings such as the need for bias voltage during operation, the susceptibility of signal acquisition to parasitic capacitance, complex structure and easy adhesion are addressed (Shi et al , 2023). The first and second research directions are both based on the principle of co-vibrating hydrophones that at low frequencies the motion of a sphere whose mass is equal to that of the water it displaces is identical to the motion of the water particles at this location when the sphere is removed (Leslie et al , 1956).…”