Analytical and high accurate formula for electrostatic force of comb-actuators with ground substrate.

Designing a comb-actuator requires calculating electrostatic force. In this paper, the analytical and high accurate formula of electrostatic force for comb-actuators with ground substrate is derived. This analytical formula enables the fringe effect to be taken into account. According to the geometric feature, the whole structure of a comb-actuator is divided into two types of units, the capacitances of which can be calculated by Schwarz-Christoffel mapping. Based on the capacitance results, the electrostatic force acting on moving fingers can be obtained by the energy method. The results of electrostatic force obtained by this analytical formula are compared with that obtained by finite element method. The compared results illustrate that the analytical formula has very high accuracy for calculating electrostatic force, which is meaningful for designing comb-actuator precisely. [ABSTRACT FROM AUTHOR]