Factors enhancing the reliability of touch-mode electrostatic actuators

This paper discusses the failure modes frequently encountered in touch-mode electrostatic actuators (TMEA) and reports on practical ways of increasing the time to failure. Humidity is identified as the main source of anomalies in the behavior of TMEA and charge trapping in the dielectric as the main cause of stiction. A method for direct charge measurement is derived and the measurements show good agreement with the calculated data. A new driving scheme is proposed that, together with surface treatments based on self-assembled monolayer, desensitizes the actuator to environmental conditions. In this way, actuators working without failure in room air for over 40 million cycles were obtained.