Bioinspired acoustic flow sensor for low-frequency underwater acoustic vector detection

Spider webs can couple acoustic signals with maximum physical efficiency over a broad frequency range. Inspired by the acoustic flow sensing mechanism of spider webs, a fiber-optic Fabry–Pérot (F–P) hydrophone is proposed. The sensitive diaphragm of the hydrophone adopts a bionic web-like structure (BWS), where the hub diaphragm of the structure and the fiber end-face form an F–P cavity. Finite element simulation is employed to optimize the geometric structure of the BWS and a full-phase spectrum demodulation method is used to demodulate the interference spectra. The test results demonstrate that the BWS hydrophone features a bandwidth of 10–2000 Hz, a sensitivity of 52.4 nm/Pa at 100 Hz and a minimum detectable pressure of 0.44 mPa/Hz^1/2, and it also exhibits favorable acoustic directivity. Furthermore, due to the hollowed-out structure of the BWS, the hydrophone is immune to hydrostatic pressure. This fiber-optic hydrophone based on the acoustic flow mechanism provides a novel strategy and solution for low-frequency, high-sensitivity underwater acoustic signal detection.