A Novel Bionic MEMS Vector Hydrophone Based on Ultralow-Frequency Detection

The microelectromechanical systems (MEMS) vector hydrophone has significant potential for application in the detection of low-frequency underwater acoustic signals. The present article proposes a novel bionic MEMS vector hydrophone (BVH) based on ultralow-frequency detection, with the aim of overcoming the problem of low sensitivity of conventional hydrophones to low-frequency underwater acoustic signals. The microstructure of the hydrophone is inspired by the inner ear of the bony fish, and the size of the microstructure is determined by finite element iterative analysis. The natural frequency of the hydrophone in a vacuum environment is determined to be 1824.3 Hz, and the natural frequency in the water medium is 514.26 Hz. The integrated manufacturing of the sensitive microstructure of the hydrophone was completed by using MEMS processing technology, and the acoustic packaging was designed and the prototype was fabricated. The experimental findings demonstrate that the working bandwidth of the novel BVH is 10–1000 Hz, and its sensitivity exceeds that of the hollow mushroom-like Cilia MEMS vector hydrophone (MCVH) within this frequency range. Furthermore, the sensor’s sensitivity exhibited a consistent and incremental rise within the 10–500 Hz range. The sensitivity at 315 and 500 Hz is −169 and −165.6 dB, respectively. Furthermore, the depth of the concave point is greater than 30 dB, indicating that the sensor exhibits favorable dipole directivity.