High‐Performance Sound Detection of Nanoscale‐Thick and Large‐Area Graphene Oxide Films in Liquids

This article presents nanoscale‐thick and large‐area graphene oxide (GO) films manufactured by a facile method to enable high‐performance sound detection in liquids. A Fabry–Perot (F–P) cavity consisting of a GO film, whose vibration diameter is ≈4.4 mm, and a single‐mode fiber (SMF) is used as the sensing core for sound detection in liquids. A sound‐transparent cap, consisting of a support sleeve and a sound‐transparent sleeve, is used to protect the GO‐sensing diaphragm to resist liquid pressure to enable long‐term stability. The sensing probes with GO diaphragms of ≈100 and 200 nm thickness are placed in ultra‐pure water for performance testing. Test results show that they maintain a linear sound pressure response, a flat frequency response, and a uniform directional response from 1 to 100 kHz. They have sensitivities of ≈630 mV Pa⁻¹ and about 84 mV Pa⁻¹, respectively, in the range of 1–100 kHz in all directions in different liquids. These results demonstrate the suitability of the nanoscale‐thick and large‐area GO films for sound detection in liquids with high performance.