A leisurely stroll could charge your cellphone

Charging your cellphone by taking a leisurely stroll might not be all that utopian but something of a working reality in the near future -- thanks to a wafer-thin device embedded in the sole of your shoe.

The device, developed by scientists from the Lawrence Berkeley National Lab (Berkeley Lab), harnesses harmless viruses to turn mechanical energy into electricity with the movement of your feet.

They tested their approach by creating a 'live' generator that produces enough power to operate a small liquid-crystal display. It works by tapping a finger on a stamp-sized electrode which is converted into electric charge by the specially engineered viruses, the journal Nature Nanotechnology reports.

Their 'living' generator is the first to produce energy by harnessing the piezoelectric properties of a biological material. Piezoelectricity is the accumulation of a charge in a solid in response to mechanical stress.

The milestone could lead to tiny devices that harvest electrical energy from the vibrations of everyday tasks such as shutting a door or climbing stairs. It also points to a simpler way to make microelectronic devices, according to a Berkeley statement.

That's because the viruses arrange themselves into an orderly film that enables the generator to work. Self-assembly is a much sought after goal in the finicky world of nano technology.

"More research is needed, but our work is a promising first step toward the development of personal power generators, actuators for use in nano-devices, and other devices based on viral electronics," says study author Seung-Wuk lee, scientist in Berkeley lab's Physical Biosciences Division.