Researchers create a 'battery-free' mobile phone

Your future phone may never need to be charged. 

That's the exciting implication of new research out of the University of Washington, where researchers have created a mobile phone prototype that doesn't require a battery to operate.

The astonishingly efficient prototype requires just 3.5 microwatts of juice, and it employs an innovative approach to avoid the need for a battery cell. Instead, it uses ambient power from radio signals and light — its onboard solar cell is "roughly the size of a grain of rice" — to transmit a signal back to a base station 50 feet away.  Read more...