Operational characteristics of microfabricated electric motors

Abstract We report on the operational characteristics of LOCOS-based microfabricated radial-gap electric motors through lifetime tests, transient measurements, modeling, and parameter extraction. We have found that the reduction of static friction (stiction) in the bearings by the incorporation of a silicon nitride film permits these micromotors to spin in normal air ambients. Frictional drag from the bearing, which results from the electric-based side-pull of the rotor, is found to be the dominant rotor-retarding force and to lead to motor wearout after approximately 10 000 rotor revolutions. Furthermore, the frictional coefficient of the nitride-on-polysilicon micromotor bearing is determined to be 0.36 ± 0.04.