MEMS Microbreaker With Electrostatically Actuated Closure and Tunable Electrothermal Reset

Microelectromechanical systems (MEMS) circuit breakers offer an attractive pathway toward miniaturized, energy-efficient, and fast-acting electrical protection systems capable of operating in harsh environments. To advance their integration within existing microfabrication frameworks, this paper demonstrates a MEMS-based circuit breaker (MCB) fabricated using the commercial PolyMUMPs process. The device employs electrostatic actuation for contact closure and Joule-heating-induced thermal recovery for reopening, enabling reversible switching. Adhesion-based latching at the contact interface is exploited so that, once closed, the breaker maintains the closed-state without any static hold power. A novel dual-air-gap configuration is implemented to enhance contact force and minimize closed-state resistance, while ensuring negligible leakage current due to high open-state resistance. Experimental characterization reveals an average closed-state contact resistance of 169 Ω at 140 V and the ability to sustain up to a 100 mA current. Under certain operating conditions, the device exhibits self-unlatching behavior when the conduction current exceeds certain values, corresponding to thermally induced release of the contact interface. This thermally induced reset current that defines the breaker trip point is tunable via the post-actuation gate bias, with the minimum current required to reopen the contacts increasing from 10 mA with no residual gate voltage to 38 mA at a 100 V gate voltage. Temperature-dependent measurements from 20 °C to 170 °C show stable conduction behavior with a temperature coefficient of resistance (TCR) of 414 ppm/°C, supporting operation in elevated-temperature and in harsh-environment applications.