Quiescent-sensing MEMS mic enables new applications

Article By : Steve Taranovich

Vesper has demonstrated the first commercially available quiescent-sensing MEMS microphone enabling acoustic event-detection devices that draw just 3µA in listening mode.

Vesper Technologies, a privately held piezoelectric MEMS company, which began at the University of Michigan, has improved the acoustic experience with a wide range of consumer products, including smartphones, smart speakers, IoT devices and connected automobiles, via a patented piezoelectric MEMS platform.

Vesper has now demonstrated the first commercially available quiescent-sensing MEMS device, a piezoelectric MEMS microphone, the VM1010. What that means is that you can design acoustic event-detection devices that draw just 3µA, while in listening mode.

[WakeUpAndListen 1 Pinout VM1010x600]
*__Figure 1:__ The pin out of the VM1010 (Source: Vesper)*

Matt Crowley, Vesper CEO says that this microphone is the only device that uses sound energy itself to wake a system from full power-down. It is known that even when fully powered-off, batteries in smartphones and smart speakers naturally dissipate 40-80µA, which is far more current than this device needs.

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*__Figure 2:__ Key specifications for the VM1010 (Source: Vesper)*

Even in sleep mode, the VM1010 preserves its high SNR, which is needed for a wider acoustic range. There is no SNR penalty from going into low power, extending the distance of far field voice control in battery-powered systems. Watch the following YouTube video, which shows the actual performance and capabilities like wake-on-sound.

When you embed this device into a voice-powered TV remote control or smart speaker, you could turn on the TV from across the room without having to push a button and without diminishing battery life.

[WakeUpAndListen 3 Block diagram VM1010x600]
*__Figure 3:__ Block diagram of the VM1010. (Source: Vesper)*

The microphone employs a rugged piezoelectric transducer that is immune to dust, water, oils, humidity, particles and other environmental contaminants, making it ideal for deployments outdoors or in kitchens and automobiles. This video shows the hydrophone capability of the VM1010.

An ideal feature of any design that uses this quiescent sensor is that essentially no power will be consumed until the appropriate stimulus occurs. To date, Peter Cooney, principal analyst and director, SAR Insight & Consulting claims that no company has demonstrated this in an actual commercial device. Therefore, in an ‘always on’ case, this solution has the potential to advance quiescent sensing into the commercial realm, enabling a new era of ubiquitous ‘always on’ sensors that can run indefinitely on small batteries.

A proof-of-concept board was used to test and evaluate performance (below).

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*__Figure 4:__ The VM1010 proof-of-concept board used to evaluate and test performance. (Source: Vesper)*

Engineering samples of VM1010 are available now to highly qualified customers developing technologically advanced systems. Production samples will be available in Q4 2016.

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