Invention Reuses Radio Signals To Charge Phones

Our mobile devices have indeed become faster and more powerful but their batteries are having a hard time catching up. The usual solutions involve bigger batteries or power banks or cases, both of which tack on bulk, weight, or inconvenience to otherwise slim smartphones. While we're still a far away from being able to almost magically charge our devices over the air, engineering researchers from Ohio State University have invented what could probably be the next best thing: a way to charge phones using otherwise wasted energy from radio signals.

Whenever our phones communicate with cell towers or Wi-Fi, like when browsing the web, making calls, or sending messages, the radio chips inside broadcast signals in all direction to reach the nearest tower or router as fast as it can. That, however, is also wasteful, causing some of the energy from these signals to be lost for good. This is the exact kind of energy that research associate professor Chi-Chih Chen and his associates are trying to harvest to feed back into smartphones.

Using radio signals as an alternative power source isn't exactly new. Some have already attempted the same to power small sensors, but the Ohio State version has one huge difference. Previous implementations pluck out the energy already in the air, which means they can only get a few micro (millionths) or nano (billionths) watts of power, enough to juice up small sensors but not to recharge smartphones, which require milliwatts (thousandths). The researchers accomplish this by going directly to the source of the radio signals, which is the smartphone itself.

The technology behind the conversion process isn't entirely new either. In fact, it forms the basis of regular smartphone chargers which transform alternating current or AC from wall outlets to direct current or DC accepted by devices. It turns out that radio waves are just very high-frequency forms of AC. But the invention goes about its radio wave to DC conversion process smartly, efficiently identifying which radio signals are being wasted and converting just enough to charge the phone without degrading signal quality. In theory, this could extend your phone's battery life by as much as 30 percent.

The one limitation of this invention is that the rectifier only works when the phone is actively communicating with towers and routers and not when, say, playing an offline game. But considering calls and browsing are the most battery draining activities, that might work just fine.

For now, the rectifiers, the components that convert AC radio signals to DC, are placed inside special smartphone cases that promise to add very little bulk to the device. Some of the inventors have formed a startup and plan to go to Kickstarter soon for funding development. In the future, they plan on reducing the case into a simple smartphone skin, and eventually even licensing the technology to be built into smartphones.

SOURCE: Ohio State University