Power delivery for remotely located microsystems

Supplying power to bio-implanted devices or to devices located in a hostile environment is an important problem. In the former case, power can be supplied by means of an implanted or a local battery, or by wires, which for a bio-implanted application results in wires penetrating through skin. This work examines a wireless power delivery system for a remotely located microsystem. The external transmitter coil and the receiver coil located with the microsystem form a loosely coupled system. A conventional rectifier circuit is used for conversion of induced receiver coil ac voltage to a de voltage. For an input supply voltage of 0.35 V_rms, the transmitted power to a 34 Ω load resistor connected to the receiver coil were 4 and 13.2 mW, when the receiver coil was placed at the center and at the rim of the transmitter coil, respectively. These values are encouraging and means for further improvement are discussed.