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 anomalie s 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 t he measurements show good agreement with the calculated data. A new driving scheme is proposed that, together with surface treatments based on self-as sembled monolayer, desensitizes the actuator to environmental conditions. I n this way, actuators working without failure in room air for over 40 milli on cycles were obtained. (C) 2000 Elsevier Science S.A. All rights reserved .