Fabrication of Acoustic Sensor Using Multilayer Transferred Monocrystal Graphene and Graphene–Polymethyl Methacrylate Composite Film Based on Extrinsic Fabry–Pérot Interference Effect

Graphene that is prepared by chemical vapor deposition (CVD) can realize the regulation of a monocrystalline layer with an arbitrary thickness through multilayer transfer method. This approach has significant advantages and potential for application in the membrane materials of extrinsic Fabry–Pérot interference (EFPI) optical fiber sensors. In this study, a series of <tex-math notation="LaTeX">1100 </tex-math> - <tex-math notation="LaTeX">μ m </tex-math> graphene–polymethyl methacrylate (PMMA) composite film EFPI optical-fiber sensors were proposed and fabricated. Through the optimization of reflectivity enhancement and assembly mode adjustment, its signal-to-noise ratio (SNR) was as high as 68.28 dB, and its minimum detection pressure (MDP) was <tex-math notation="LaTeX">47 μ </tex-math> Pa/Hz <tex-math notation="LaTeX">1/2 </tex-math> at 6 kHz. The preparation process was characterized by simplicity and low manufacturing costs. Additionally, a <tex-math notation="LaTeX">1100 </tex-math> - <tex-math notation="LaTeX">μ m </tex-math> 30-layer monocrystal graphene-film EFPI sensor was prepared, which realized thin-film suspension support under an extremely high diameter-to-thickness ratio. Its SNR was 53.92 dB at 6 kHz, and its Pearson correlation coefficient was 0.83, which was consistent with the frequency response of the loudspeaker output characteristics. The results of this study could provide solutions to meet different application requirements for acoustic pressure detection of EFPI fiber-optic sensors.