Shaking your cellphone to recharge it?

US researchers say they are working on a new cellphone charging system that turns movement into energy, allowing a phone to be recharged by simply shaking it. Researchers at Virginia Tech are designing an emergency onboard charger that draws energy from a common piezoelectric material that can convert vibrations into energy to power a phone, NewScientist.com reported Tuesday. Vibrating the material -- zinc oxide -- produced an electrical current at about 50 millivolts, they said. The vibrations could come from finger taps on the phone's keyboard or by shaking the phone, they said. While it wouldn't produce a great deal of power -- not nearly enough to continuously operate the phone -- it would be sufficient for an emergency situation, researcher Shashank Priya said. "In an emergency you could just shake your cellphone for a few minutes to get enough power to make this one important call," he says.