This piezo MEMS Microphone patent was filed back in 2020 and was granted 1 March 2022. “The invention provides a piezoelectric micro-electromechanical system (MEMS) microphone includes a base with a cavity and a piezoelectric diaphragm arranged on the base.” Right now, this appears to be the only significant competitor device to Vesper MEMS products.
Whether AAC has any intention of bringing products to market remains to be seen but it would be a major confirmation of piezo usage for MEMS microphones and may lead to increase usage of the technology in devices.
The patent says, “One of the major objects of the present invention is to provide a piezoelectric MEMS microphone with improved sensitivity.” A few years ago, the higher SNR possible with piezo MEMS microphones was one of the major selling points but increases in SNR have become difficult, and now with new silicon MEMS designs such as Infineon’s XENSIVTM SNR now surpasses that for piezo.
It will be interesting to see if new AAC piezo MEMS products enter the market.