Analysis of lateral stability of electrostatic comb-drive structure

Electrostatic comb-drive actuators have been widely used in MEMS field. In general, the traveling ranges of comb-drive actuators are limited by the lateral instabilities which cause a sudden snap between the movable comb fingers and the fixed fingers, resulting in functional failure. The lateral stability of the typical electrostatic comb structure was investigated. From theoretical simulations and experimental verifications, it was found that the ratio of lengthwise stiffness to transverse stiffness of the suspensions is a key factor for lateral stability. With increased stiffness ratio, the lateral stability of comb-drive structure is improved.