Researchers in the US have tweaked a regular Wi-Fi router and made it capable of continuously powering a battery-free surveillance camera. Even better, their work didn’t interfere with the router's data transfer speeds.
The breakthrough could help researchers overcome one of the main challenges when it comes to the development of new technology - including the Internet of Things, which aims to put a chip inside all our household appliances and bring them online: how do we keep everything powered up without lots of cords?
Researchers have long known that the electromagnetic waves broadcast by Wi-Fi routers could be harnessed for energy as well as sending information, but the challenge was finding a way to do this reliably and continuously. A team from the University of Washington in the US has now accomplished this by simply changing the way a router broadcasts. They’re calling their new approach ‘power over Wi-Fi’ or PoWi-Fi.
"The ability to deliver power wirelessly to a wide range of autonomous devices and sensors is hugely significant," writes MIT's Technology Review. "PoWi-Fi could be the enabling technology that finally brings the Internet of Things to life."
In the past, scientists have never been able to harness enough Wi-Fi signals to power anything of much use. But the team’s big break came when they attached a simple antenna to a temperature sensor in order to see how much power they could get from a nearby router.
They found that the resulting voltages produced by the Wi-Fi signals were never high enough to cross the operating threshold of around 300 millivolts. But they often came close.
The problem, they realised, was that Wi-Fi routers don’t continuously blast out electromagnetic waves, they send them out on a single channel in bursts. But by programming a router to broadcast noise across a range of Wi-Fi channels even when it wasn't transmitting information, they were able to pump out enough signals that their antenna could then use to provide continuous power to electronic devices.
Using their prototype, the team managed to show for the first time that they could not only run battery-free temperature and camera sensors using Wi-Fi signals from a distance of six and five metres respectively, they also proved that they could charge a range of coin-cell batteries at distances of up to nine metres.
They then took their system into six metropolitan homes to show that the set-up worked in real life, and didn’t interfere with data transfer speeds. The results are published over at arXiv.org.
The question that needs to be answered now is how these routers interfere with other signals in the area. “Having a router next door that is blasting out signals on three Wi-Fi channels might not be everybody’s idea of neighbourly behaviour,” writes MIT’s Technology Review. “It is worth pointing out, however, that if this kind of interference turns out to be a problem for current routers, it is one that could be solved in future generations.”
The next step is further testing on these routers under a range of different conditions to make sure they really can help to provide us with regular power for our devices while we browse the Internet. And if that’s the case, then it could seriously change the way we power up our homes. We can’t wait.