The tyranny of the phone charger is just about over. That wire, the pronged plug - the panic when the charger has been left at home. It's so over, so 20th century. In the future, we'll be able to power up our devices with a wave of the hand, a short walk or via our heartbeats, said engineers from the Georgia Institute of Technology on Thursday. Batteries are now a thing of the past, they said, thanks to nanotechnology that converts mechanical energy from body movements to electrical energy.