Analyzing the applicability of miniature ultra-high sensitivity Fabry–Perot acoustic sensor using a nanothick graphene diaphragm

Abstract

A miniature Fabry–Perot interferometric acoustic sensor with an ultra-high pressure sensitivity was constructed by using approximately 13 layers of graphene film as the diaphragm. The extremely thin diaphragm was transferred onto the endface of a ferrule, which had an inner diameter of 125 μm, and van der Waals interactions between the graphene diaphragm and its substrate created a low finesse Fabry–Perot interferometer with a cavity length of 98 μm. Acoustic testing demonstrated a pressure-induced deflection of 2380 nm kPa−1 and a noise equivalent acoustic signal level of ~2.7 mPa/Hz1/2 for a 3 dB bandwidth with a center frequency of 15 kHz. The sensor also exhibited a dynamic frequency response between 1 and 20 kHz, which conformed well to the result obtained by a reference microphone. The use of a suspended graphene diaphragm has potential applications in highly sensitive pressure/acoustic sensors.

Noise Properties of Graphene-Polymer Thick-Film Resistors

“…Its outstanding properties make it an ideal material for various applications, e.g. optoelectronics [1], RF communications [2], strain and pressure sensors [3,4]. Due to its very high thermal conductivity, graphene is also used in electronic devices as a heat dissipation material [5].…”

Ultrasensitive Pressure Detection of Few‐Layer MoS2

“…Diaphragms with thin thicknesses and high mechanical strength are crucial for achieving high sensitivity, which is defined as the ratio of the F–P cavity's length variation to the applied pressure. By measuring the deflection deformation of the diaphragm, the corresponding applied pressure can be determined . In order to achieve high sensitivity, large deflection deformations of diaphragms at the same applied pressure are desirable.…”

“…After graphene was discovered in 2004, a family of 2D layered materials with atomically thin thicknesses attracted increasing research activity due to their unprecedented properties and possible applications in diverse fields . In our previous work, multilayer graphene film with Young's modulus of ≈1 TPa and Poisson's ratio of ≈0.17 was used as a diaphragm material for F–P sensors with a high sensitivity (2.38 × 10 3 nm kPa −1 ),[1a] which is two orders of magnitudes higher than that of traditional thin‐film materials (e.g., 11 nm kPa −1 for silica hydrogen‐evolution‐reaction (HER) electrodes, photodetectors, transistors, and tactile or gas sensors .…”

“…The total intensity of the reflected light is the sum of the two reflected beams (reflected lights 1 and 2 in Figure S8, Supporting Information). By applying the theory of interference, the reflective interference intensity I r can be expressed as:[1a]where R 1 and R 2 are values of reflectivity of MoS 2 diaphragm and fiber end/air interface, respectively; δ is the phase difference of two reflected beams; I i is the intensity of the incident light, and ξ is the coupling coefficient of cavity length loss and is related to the wavelength and cavity length, which could be described by the equation as below:[1a]…”

“…An excellent linear fit can be obtained for experimental data. e) Comparison of sensitivity of different diaphragm materials (data sources: thin graphene film,[1a] thick graphene film, thin silver film, thick silver film, silica film, polymer/metal film, and the MoS 2 films in this work).…”