A High-Flatness Pmut-Based Hydrophone System For Large Bandwidth Underwater Acoustic Detection

Low-frequency broadband acoustic detection is critical for applications such as ocean exploration and seismic monitoring. Conventional hydrophones often exhibit poor sensitivity flatness, necessitating complex post-processing that can introduce signal distortion. This study introduces a high-flatness hydrophone system based on piezoelectric micromachined ultrasonic transducers (PMUT). Utilizing an array configuration, the size of the vibrating membranes is reduced while enhancing the effective vibrating area, thereby increasing the resonance frequency without compromising sensitivity and shifting it outside the operational frequency range. The PMUT -Based hydrophone achieves a sensitivity flatness of within 1.6 dB <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$(\pm 0.8\text{dB})$</tex> over a broad frequency range (20 Hz - 2000 Hz), withstands water pressures up to 10 MPa, and maintains nonlinearity within 4.3%. Minimal sensitivity fluctuation across this range indicates a strong potential for broadband deep-sea detection.