Wearable Stethoscope Based On Resonant Microphone Array With Wireless Data Transfer

RMA is built on a silicon-on-insulator (SOI) wafer using a shared window for fitting two width-stepped cantilevers in one window to reduce pressure leakage through the air gaps around the cantilever edges. Four resonant microphones are used in the array to cover the entire frequency range. The highest unamplified sensitivity in the array is measured to be 94.4 mV/Pa at 330 Hz, which is more than 4 times that of any commercially available condenser microphone. Experimental results show more prominent wheezing signatures in the spectrogram of the signals obtained with RMA compared to those with a reference microphone. A folded printed circuit board (PCB) houses ultra-low-power op Amps, filters, a commercial wireless chipset (CYBLE-416045-02) with a built-in antenna for Bluetooth communication, and a battery. Data transfer is obtained through Bluetooth low-energy (BLE) communication from the wireless chipset to a mobile phone. The wearable and wireless stethoscope (including the RMA, electronics, and battery) weighs 33.2 g, and can continuously pick up sounds with the RMA and send the data through BLE for several hours.