Advantages of alternative actuating signal for MEMS actuators

In this paper, we report the different advantages of using AC actuating signal for driving MEMS actuators. The study is based upon micro-mirror devices used in scanning or digital mode. In scanning mode, an AC signal can be used to overcome difficulties induced by the high voltages required in electrostatic systems by taking advantage of the double rectifying effect of electrostatic actuation within a second order system. On the other hand, when the pull-in effect is used, charge injection occurs after a long time in the deflected position except when the landing electrodes are electro-statically separated from the control electrodes. An AC signal also eliminates charge injection particularly if a bipolar signal is used. Long term experiments have demonstrated the reliability of such a signal command to avoid injection of electric charges.