An ultra-high sensitivity Fabry-Perot acoustic pressure sensor using a multilayer suspended graphene diaphragm

A 10~15-layer suspended graphene diaphragm was adhered onto the endface of a ferrule with a 125-μm inner diameter by van der Waals interactions to construct a miniature ultra-high sensitivity Fabry-Perot acoustic sensor. Considering the dynamic acoustic pressure measurement, the properties of film natural frequency and optical reflectivity were investigated by ANSYS modal simulation and Fresnel´s equation, respectively. The average reflectivity of the multilayer graphene diaphragm was measured to be about 1.49%. Acoustic testing demonstrated a pressure-induced deflection of 2.38 nm/Pa at 15 kHz with a nice omnidirectionality. The sensitive diaphragm structure breaks the sensitivity limitations imposed by the increased thickness and the decreased dimension of a diaphragm used in traditional Fabry-Perot pressure sensors.