The sensing device is a MEMS microphone that outputs a pulse density modulated (PDM) signal. There are chips available to directly interface such a microphone to a USB port, but [Mahesh] found ...

Deciding to go for a full digital design for the circuitry, the peripheral is based off of a MEMS microphone and an STM32 microcontroller doing the heavy lifting between it and a USB connection.

X-FAB to Provide Foundry Services for Akustica's Family of CMOS MEMS Silicon Microphone Chips ERFURT ... fabrication methods by which those products are manufactured. CMOS MEMS structures are composed ...