The ability to charge your cell phone literally from the thin air may someday be possible if experiments at the Nokia Research Center here come to reality.

Researchers are studying how to convert ambient electromagnetic radiation, such as that emitted from wi-fi devices, cell phone towers and TV masts, into electrical signals that could recharge cell phones.

The concept is similar to the manner in which crystal radio and RFID tags are powered.

Markku Rouvala, who is leading the work, said his group hopes to produce a cell phone that can "harvest" up to 50 milliwatts of power, enough to slowly recharge a phone that is turned off. So far, a prototype phone can harvest 3 to 5 milliwatts, according to Rouvala. He believes that a working model would have to receive many more frequencies than the current operating range of cell phones.

A researcher at the University of Washington in Seattle said earlier this year that the production of 50 milliwatts of electricity could require about 1,000 strong signals.

"I reckon if it's possible, then it'd be something pretty spectacular," wrote James Collins, a blogger for Nokia. "The notion that you could just put your phone down and it'd be charging itself would be pretty awesome."