Home device listens for fire alarms, then shuts all doors

A novel "zero power" microphone is behind the "always on" fire safety device.

Vesper MEMS microphone

Vesper MEMS microphone Vespermems.com

Matthew McKee Photography

Sprinklers help stop fires, but most houses aren't equipped with them. Turns out another way to help fires from spreading inside a home is decidedly low tech: Shut interior doors to keep the fire from easily moving outward. 

"Eighty percent of children sleep through a smoke alarm," says Joel Sellinger, a firefighter. "Unfortunately, house fires are increasing in frequency and spread 600% faster today as compared to 40 years ago. Ten years of research by the Underwriters Laboratories Firefighters Safety Research Institute shows that fire is getting faster and that a closed-door makes a 900-degree difference."

That's a good tip, only running around shutting doors probably isn't your first instinct when a fire alarm goes off. And since many fires happen when residents are sleeping or out of the house, the odds of successfully containing a fire this way are slim. 

A product called LifeDoor, cofounded by Sellinger, takes a stab at a solution. It's a smart home gadget that's tuned in to the sound of home fire alarms and automatically closes the doors. And the "always-on" microphone technology behind it is equally impressive.

Now, if flashes of scenes from smart-house-gone-awry flicks like Tau or Ex Machina are flitting through your minds ("let us out!"), I don't blame you. But LifeDoor doesn't lock people in, just gets the doors closed. The device also lights up the room and sounds a secondary alarm to alert occupants. The embedded microphones register the sound of the smoke detector, prompting the door closure, and the door is then easily reopened if that's the safest way to exit the home.

Those embedded microphones are designed by a company called Vesper and consume next to no power. The little mics utilize piezoelectric MEMS technology, which is both durable and practically power free, making them ideal for activating devices in deep sleep mode.

"Vesper's ZeroPower Listening technology has enabled an entirely new class of smart home products that use audio event detection in battery-powered devices," says Vesper CEO Matt Crowley. "Embedding Vesper's ZeroPower Listening microphones in an innovative device like LifeDoor's literally saves lives. We are proud to support the founders of LifeDoor in this important mission."

Vesper has a connection to another always on the listener: It's backed by Amazon Alexa Fund. Brings new meaning to the command: "Alexa, turn down the heat.