Hearing Aid Sensitivity Optimization on Dual MEMS Microphones Using Nano-Electrodeposits

Abstract

We present an in-situ sensitivity tuning method for MEMS (micro-electromechanical systems) microphones via the growth/retraction of nano-electrodeposits to achieve high directionality in hearing aid applications. Nano-electrodeposits are electrochemically grown and dissolved on an Ag-doped Ge-Se solid electrolyte film on a microphone diaphragm using a DC bias at room temperature. The growth and retraction of the nano-electrodeposits generate mass/stress redistribution on the diaphragm, tuning the microphone sensitivity to incoming acoustic sources. Acoustic measurements demonstrate that the directional microphone can achieve a 1.3 dB Directivity Index (DI) improvement upon nano-electrodeposit growth and 0.9 dB DI reversal on nano-electrodeposit retraction