Computation of electrostatic forces with edge effects for non-parallel comb-actuators

The formulas for the capacitance and electrostatic force in a non-parallel comb-drive actuator were derived to accurately predict the electrostatic force. In actual electrostatically actuated micro-electromechanical devices, the capacitance edge effects are very significant, which greatly alter the electrostatic force. Therefore, the equations for the electrostatic force include the edge-effect for parallel and non-parallel comb-drives. The equations compare well with the results of a 3-D finite element method simulation. Therefore, the equations including the edge-effects can be used when parallel capacitor models are not sufficiently accurate.