Dynamics of MEMS Microengines Using Optoelectronic Laser Interferometry

Abstract

AbstractWe have developed an optoelectronic laser interferometry microscope (OLIM) methodology for rapid characterization of MEMS' motion dynamics. In this study, electrostatic comb drive actuated microengines comprised of a 64 μm diameter drive gear and a 300 μm output gear (load gear) were characterized dynamically. Two different input signals were used: 1) a four-step square wave input and 2) an optimized input signal calculated from an analytical model. Out-ofplane motion on rotating microgears was measured as a function of the input signals. The outof-plane motions for the drive during the four-step input ranged from zero to ±462 nm and from zero to ±514 nm for the drive and output gears, respectively. For the optimum input, the out-ofplane motions ranged from zero to ±1030 nm for the drive gear. However, for the output gear the tilt magnitudes were nearly constant at ±514 rum, and were independent of angular position. The more constant out-of-plane motions of the load gear for the optimized signal are due to improved kinematics and kinetics leading to more continuous rather than impulsive forces (e. g., frictional, inertial) acting on the output gear.