Sensors and Actuators Abstract

Study of contacts in an electrostatically actuated microswitch

Sumit Majumder, N.E. McGruer, George G. Adams, P.M. Zavracky, Richard H. Morrison and Jacqueline Krim


Surface micromachined, electrostatically actuated microswitches have been developed at Northeastern University. Microswitches with gold contacts typically have an initial contact resistance of the order of 0.1 Ohms over the first 10^5 cycles of lifetime while cold-switching 4mA, and have a current handling capability of about 20mA. In general, the contact resistance decreases over the first few thousand switch cycles, and degrades progressively when the switches are cycled beyond approximately 10^6 cycles. In this work, the microswitch contact resistance is studied on the basis of a clean metal contact resistance model. Comparison of the measured contact resistance (measured as a function of contact force) with the characteristics predicted by the model shows approximate agreement. The discrepancies between the model characteristics and measurements are discussed briefly.

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