Tiny wireless sensor never needs a battery

This minuscule temperature sensor gets power from its own wireless networking.

The internet of things is a nice idea, but there's one big catch: you have to power all those smart devices, which is no mean feat when some of them might not even have room for a battery. Dutch researchers think they have a solution, though. They've built an extra-small (2 square millimeters) wireless temperature sensor that gets its power from the radio waves that make up its wireless network. All it needs is energy from a nearby router -- once there's enough, it powers up and starts working.

Right now, the sensor can't be further than an inch from its host, which isn't exactly practical. Thankfully, this isn't the end of the story. The team hopes to extend that range to nearly 10 feet within a year, and ultimately to 16 feet. If the network-based power takes off, you could see smart homes full of virtually invisible sensors that control all your devices. You could have lights that turn on the moment you enter any room (not just those you care about the most), or heating that shuts off as each room warms up. The best part may be that these sensors would be very cheap, at about 20 cents each. At that price, it wouldn't cost a fortune to make the upgrade.

[Image credit: Bart van Overbeeke/Eindhoven University of Technology]