Pull-in instability of parallel-plate electrostatic microactuators under a combined variable charge and voltage configuration

In this letter, we present a theoretical analysis of pull-in instability of parallel-plate electrostatic microactuators under a combined variable charge and voltage configuration. This occurs in parallel plate capacitors partially filled with a charged dielectric (electret) where the plates are connected together through an impedance. Our results demonstrate the possibility of achieving full range motion under certain conditions. For Teflon (R) electrets much thinner than the air gap; the maximum traveling distance is similar to the voltage controlled electrostatic actuators (gap/3), whereas for electrets four times thicker than the initial gap the maximum traveling distance can approach 100% of the gap. (c) 2008 American Institute of Physics.