Imagine a future where battery life isn't about how fast a gadget charges or how long it lasts, as everything runs without batteries. While that's still a long way off, one gadget has been developed that runs off radio waves for power.

A temperature sensor has been created that's able to measure and deliver figures purely using radio waves. It's not too dissimilar to the way RFID works in your contactless payment card. But this has far higher power use and consumption as it's a working sensor not just data transmission.

The 2 milimeter square sensor weighs in at just 1.6 milligrams and communicates temperature with a nearby router. It's even able to operate through layers of paint, suggesting it could be used in buildings invisibly in the future.

The researchers at Eindhoven University say that this is just the start and future sensors could measure movement, light and humidity. Imagine all your smartphone's sensors suddenly using no power, that should help battery life plenty. Or picture a host of smarthome sensors that don't require wiring in or batteries - paint with smart sensors included perhaps?

So what's the downside? At the moment the temperature chip is limited to a transmission range of just 2.5 centimeters. Researchers say it's early days and that should be bumped to one metre within a year and five metres ultimately.

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