Going Viral; August 2012; Scientific American Magazine; by Carrie Arnold; 1 Page(s)

In their search for eco-friendly energy sources, scientists have learned how to harness power from ever smaller living things: first corn, then algae, now bacteria. By figuring out how to generate electricity using the M13 bacteriophage, a virus that infects bacteria, engineers at the University of California, Berkeley, have gone smaller still. Although the virus-powered device produces only a tiny bit of energy, it may one day pave the way for cell phones that can be charged while you walk.

The device relies on a property known as piezoelectricity, which can translate mechanical energy, say, a finger tap, into electrical energy. Most cell-phone microphones are piezoelectric and convert the energy from sound waves into electrical output that is transmitted and translated back into sound waves in the recipient's phone. The problem with these piezoelectric devices, Berkeley bioengineer Seung-Wuk Lee says, is that they are made out of heavy metals such as lead and cadmium. Many biomolecules such as proteins and nucleic acids are also piezoelectricthey generate electricity when compressedbut lack the toxicity of traditional devices.