Pulse and DC operation lifetimes of bent-beam electrothermal actuators

This paper reports on lifetime studies of polysilicon and p/sup ++/ Si electrothermal actuators designed for rectilinear displacements. Measurements show that degradation patterns for displacement amplitude can be linked to design variables and operating conditions. At low power levels (which result in average operating temperatures of 300-400/spl deg/C), both types of devices provide continuous DC actuation for >1400 min. and pulse actuation for >30 million cycles without change in amplitude. A model similar to that used for fatigue in steel is used to fit pulse test data for p/sup ++/ Si actuators. The model parameters are explored as functions of operating conditions and device geometry.