Not quite at the point of harvesting energy from passing em waves and making batteries obsolete, but still a major advance from the current nuisances of carrying a host of charging devices and looking for compatible plugs: WiTricity has signed a technology transfer and licensing agreement with MediaTek, a semiconductor company in Taiwan, to collaborate on systems for wireless charging of mobile handsets, tablet computers, game controllers and other devices, Mr. Giler said. WiTricity is also developing technology for wireless charging of electric vehicles and, later, for use in implanted medical devices like heart pumps, said Katie Hall, its chief technology officer. The technology is based on magnetic induction — the process used to recharge electric toothbrushes. In the toothbrush, the base has a magnetic coil that generates a magnetic field.