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.