The batteries used in remote controls can be costly to replace-and they seem to run out of juice at the most inconvenient times. MIT Media Lab researchers Joseph Paradiso and Mark Feldmeier have devised a way to eliminate this hassle: a batteryless controller powered solely by the energy that goes into pressing its buttons.The control (photo) contains a piezoelectric material that produces a voltage pulse when compressed. This electricity powers a wireless transmitter that can send a digital code more than 20 meters. The researchers have demonstrated this concept in a keyless car-entry remote. The same technology could also replace the batteries in TV remote controls. Products incorporating the controller could be on the market within two years.