MIT Researchers Transmit Wireless Electricity

Scientists at the Massachusetts Institute of Technology have figured out a way to transmit electric power over the air, meaning one day your cell phone could recharge itself without your having to plug it in. They're calling it Wi-tricity — short for "wireless electricity."

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STEVE INSKEEP, host:

Okay, you can already get on the Internet without being plugged in. You can go wireless. Now, imagine if your cell phone or laptop could recharge the batteries without being plugged in. That is the promise of a new trick announced by MIT researchers yesterday. They're calling it Wi-tricity, for wireless electricity.

NPR's Nell Boyce has more.

NELL BOYCE: A few years ago, Marin Soljacic had a problem. He kept getting woken up in the middle of the night by his cell phone.

Professor MARIN SOLJACIC (Physics, MIT): It would make this really loud and unpleasant noise.

BOYCE: Because its battery was low and it wasn't plugged in.

Prof. SOLJACIC: One night at 3 a.m., it occured to me well, wouldn't it be fabulous if this thing took care of its own charging?

BOYCE: Soljacic is a physicist at the Massachusetts Institute of Technology. So he started thinking. Now he's come up with a prototype charger and receiver. They're copper coils about two feet wide.

Prof. SOLJACIC: It's a carefully designed shape. And depending on the shape, they have a characteristic frequency that belongs to them.

BOYCE: Both coils share that resonant frequency, so they exchange energy fairly efficiently. One coil gets attached to the power source. The other goes on the device - in this case, a light bulb. In the journal Science, Soljacic and his team showed that they can light a 60-watt bulb from seven feet away. Soljacic says a lot more work is needed before something similar powers your laptop.

Prof. SOLJACIC: We would like to shrink these coils. We would like to be able to transmit over bigger distances.

BOYCE: And it needs to be even more efficient. Right now, less than half the power reaches the device. Still, his group is ready to license the technology. He says if a company worked hard, it could have devices on the market in just a few years.

Nell Boyce, NPR News.

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