Wireless electrical power to sub-millimeter robots

A sub-millimeter scale coil is investigated as an alternative means to power electronics for small-scale robots. The AC voltage is induced by time-varying magnetic field. FEM analysis of employing magnetic field concentrators to increase the field density is carried out, concluding with their ineffectiveness to offset the occupied space. The choice of conductive versus non-conductive photoresist is investigated. The coil fabrication process is based upon three-dimensional, two-photon-absorption photolithography. Additional steps include metal sputtering, microlaser patterning and wire-bonding. The steps detailing the entire design process are described. With the coil occupying a volume of 0.45 pico m3, the maximum AC voltage of approximately 84 nV, with power density of about 1.96 mW per meter cube were measured. The study concludes with proposing ways to increase the induced voltage to a useable voltage of 2 V.