Design issues in electrostatic microplate actuators: device stability and post pull-in behaviour

In this work, electrostatic stability of microplate actuators is investigated. In particular, the possibility to improve device stability by adopting charge control is discussed. The parallel plate actuator is first introduced as case study. Then, a one degree-of freedom model is obtained for microplate electromechanics. The parasitic capacitance arising from the non-uniform device deformation is evaluated. This practically leads to a reduced capacitance feedback with respect to parallel plate systems. Consequently, a limited stabilizing effect of charge drive can be obtained. The analysis of microplate behaviour is completed by the evaluation of adhesion (stiction) when eventually pull-in is reached.