Variable-capacitance micromotor with levitated diamagnetic rotor

A novel micromotor is described, in which the gear-shaped pyrolytic graphite rotor is levitated, rotated and constrained by the combination of static magnetic, electrostatic forces and torques. Two concentric ring-shaped permanent magnets are presented, which are used for realising the static magnetic field. By the microelectromechanical systems process, the metal electrodes, pads and SU-8 column post were fabricated on the silicon substrate above the magnets. The stator was assembled by the silicon and the magnets. The three-phase axial variable-capacitance motor principle was applied for driving the rotor. The rotor is stably levitated to a height of about 0.70 mm over the magnets. When a 30 V driving voltage was added, the rotor speed was over 10 rpm in atmosphere.