Lixuan Li

To enhance low-frequency detection sensitivity and achieve omnidirectionality in underwater acoustic sensors, this paper reports a hexagonal array piezoelectric MEMS acoustic sensor (HAAS). The HAAS comprises six identical triangular cantilever beams symmetrically arranged in a regular hexagon. This array configuration enables signal superposition to boost sensitivity, while the multi-degree-of-freedom vibrating membrane promotes omnidirectionality in underwater acoustic detection. The distinctive hexagonal array structure imparts exceptionally high sensitivity in the frequency range of 630Hz to 1.6kHz (−161.2 dB at fixed 1.6kHz,ref.1 V/ $\upmu $ Pa) and superior omnidirectional directivity, with nonuniformities of ±0.5 dB in the horizontal plane and ±0.3 dB in the vertical plane at 2 kHz. Experimental results demonstrate the substantial potential of the HAAS for applications in underwater biological activity monitoring, communication, and resource exploration.[2025-0191]

Inspired by marine mammals’ exceptional low-frequency hearing, we present a biomimetic cochlea-like scandium-doped aluminum nitride MEMS hydrophone (BCMH) for miniaturized, high-fidelity underwater acoustic sensing. The device employs a compact spiral stress-sensing architecture, achieving a flat receiving sensitivity of $- 167.7~\pm ~1.1$ dB (re V/ $\mu $ Pa), excellent omnidirectivity ±0.5 dB vertical and ±0.9 dB horizontal, with lower than the self-noise base of the first-order sea state. Enabled by bioinspired cochlear geometry and advanced piezoelectric materials, it offers a practical, high-performance solution for low-frequency seismic monitoring and next-generation underwater acoustic sensing, surpassing conventional hydrophone technologies.

MEMS vector hydrophones are poised to become the core devices of miniaturized underwater acoustic sensing. However, existing MEMS vector hydrophones suffer from low sensitivity and shallow concave point depth, which hinders long-range detection. In this work, we present an axisymmetric bionic seal whisker–type piezoelectric MEMS vector hydrophone (ASWVH) that leverages bioinspired geometries and stress-concentration regions to amplify piezoelectric output, yielding enhanced directivity and high sensitivity. The optimal microstructure dimensions for ASWVH were determined using COMSOL 5.6 simulations. The biomimetic seal whisker structure not only ensures an operational frequency bandwidth of 20–2000 Hz but also expands the effective acoustic reception area, thereby further enhancing sensitivity. The unique wavy bionic sealing whisker shape provides high sensitivity, and the measured X-axis and Y-axis sensitivities are -171.7 dB and -173.2 dB@2 kHz (re. 1 V/μPa), respectively. Moreover, the device exhibits an exceptional “8”-shaped directivity pattern with concave point depth exceeding 40 dB in both channels, rendering it well-suited for high-precision passive underwater detection.