A reliable MEMS switch using electrostatic levitation

In this study, a microelectromechanical system (MEMS) beam is experimentally released from pull-in using electrostatic levitation. A MEMS cantilever with a parallel plate electrode configuration is pulled-in by applying a voltage above the pull-in threshold. An electrode is fixed to the substrate on each side of the beam to allow electrostatic levitation. Large voltage pulses upwards of 100 V are applied to the side electrodes to release the pulled-in beam. A large voltage is needed to overcome the strong parallel plate electrostatic force and stiction forces, which hold the beam in its pulled-in position. A relationship between bias voltage and release voltage is experimentally extracted. This method of releasing pulled-in beams is shown to be reliable and repeatable without damaging the cantilever or electrodes. The proposed approach is of great interest for any MEMS component that suffers from the pull-in instability, which is usually irreversible and permanently destroys the device, as electrostatic levitation allows pulled-in structures to be released and reused. It has a promising application in MEMS switches by creating a normally closed switch as opposed to current MEMS switches, which are normally open.