Researchers at the University of Washington have the answer to a dead cell phone battery: Get rid of the battery altogether.Using off-the-shelf parts, the team assembled a phone that harnesses the power of radio waves emitted by FM radio and TV towers. The phone can also be powered by a custom-made base station.With a power limit of 3.5 microwatts, the experimental phone requires a fraction of the 100 milliwatts of power that a conventional phone needs to make a call. Although the prospect is exciting, this is still very much a technology of the future. As of now, the phone can only be used within 50 feet of the base station, much closer than the several-mile range of most cell phones.
The phone also requires that callers press a button when switching between talking and listening, similar to a walkie-talkie. But this new technology could make a difference one day when an emergency call can be made on a phone that’s out of power.