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

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 mu m, 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 mu m. Acoustic testing demonstrated a pressure-induced deflection of 2380 nm kPa(-1) and a noise equivalent acoustic signal level of similar to 2.7 mPa/Hz(1/2) 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.