Laterally driven electrostatic repulsive-force microactuators using asymmetric field distribution

We present a new electrostatic actuation method using a lateral repulsive-f orce induced by an asymmetric distribution of planar electrostatic field. T he lateral repulsive-force has been characterized by a simple analytical eq uation, derived from a finite element simulation. Quality-factors are estim ated from the computer simulation based on creep flow model. A set of repul sive-force polycrystalline silicon microactuators has been designed and fab ricated by a four-mask surface-micromachining process. Static and dynamic r esponse of the fabricated microactuators has been measured at the atmospher ic pressure for the driving voltage range of 0-140 V. The static displaceme nt of 1.27 Irm is obtained at the de voltage of 140 V. The resonant frequen cy of the repulsive-force microactuator increases from 11.7 kHz to 12.7 kHz when the de induction voltage increases from 60 V to 140 V. The measured q uality-factors are increased from 12 to 13 in the voltage range of 60-140 V . Fundamental characteristics of the force, frequency and quality-factor of the electrostatic repulsive-force microactuator have been discussed and co mpared with those of the conventional electrostatic attractive-force microa ctuator.