On electrostatic actuation beyond snapping condition

Electrostatic parallel-plate actuators are a common way of actuating MEMS devices, both statically and dynamically. In the static case, the actuation range is limited to 1/3 of the initial actuation gap, known as the static pull-in condition. Under dynamic actuation conditions, however, the travel range can be much extended. This paper extends the analysis of pull-in instability to the dynamic case and derives the analytical AC dynamic pull-in condition. This condition predicts snapping or pull-in of the structure for a given domain of DC and AC actuation voltages versus quality factor. Analytical and experimental results are presented to validate the dynamic pull-in condition