Graphene-Based Fabry-Perot Acoustic Sensor Aided by Miniature Sound Amplification Structure

We demonstrate a miniature high-sensitivity Fabry-Perot (FP) acoustic assembly composed of an FP sensor with multilayer graphene diaphragm and an aided sound pressure amplification structure (SPAS). Based on the principle of force conduction amplification, the SPAS with dual 10-
$\mu \text{m}$
-thickness E-shaped copper diaphragms interconnected with a 3-mm-length stepped PMMA round rod enables the acoustic sensor to exhibit up to 40.65 times higher acoustic sensitivity in the frequency range of 0.2-4 kHz compared with the reference electrical microphone, in combination with the use of anti-reflective coating for multi-beam interference suppression in FP compound cavity. Moreover, an extremely high acoustic pressure sensitivity was measured to be 1351.4 mV/Pa at 1.8 kHz with a minimum detectable sound pressure of
$32.4~\mu $
Pa/Hz
$^{1/2}$
, which contributes to long-distance weak sound detection application.