We present a new electrostatic actuation method using a lateral repulsive-force induced by an asymmetric distribution of electric field. The asymmetric electric field is induced when an electrostatic induction voltage is applied between a movable electrode and a pair of adjacent fixed electrodes. A simple analytical equation of the repulsive force has been derived from a finite element simulation. A set of repulsive-force polysilicon microactuators has been designed and fabricated by a 4-mask surface-micromachining process. Static and dynamic drive tests of the fabricated microactuators have been performed at atmospheric pressure for a varying induction voltage. The static displacement of the fabricated microactuator is proportional to the square of the DC induction voltage and is obtained as 1.27μm for the DC induction voltage of 140V. The dynamic amplitude of the fabricated microactuator has been measured as 1.9μm for the DC induction voltage of 140V with the AC drive voltage of 20V. The resonant frequency of the repulsive-force microactuator increases from 11.7 kHz to 12.7 kHz when the DC induction voltage increases up to MOV. The characteristics of the repulsive-force drive have been discussed and compared with those of the conventional attractive-force actuation.

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