Electric micromotors: Electromechanical characteristics

The fabrication of planar rotary and linear motors using silicon micromachining is discussed. These motors, referred to as micromotors, have a gap separation on the order of 1 micron, and lateral dimensions on the order of 100 microns or more are examined. An analysis of electromagnetic-to-mechanical energy conversion is presented to demonstrate that electric drive is preferable to magnetic drive in micromotors. This is followed by a discussion of the geometry, design, and operation of electric micromotors, emphasizing the duality of electric and magnetic motors. A prototype design for the rotary variable-capacitance micromotor is considered as an example. Rotor speeds over 105 rad/s and accelerations over 109 rad/sq s appear possible. Some of the research problems posed by the development of micromotors are identified.