Power Output Force Generation by a MEMS Phase Change Actuator

A microelectromechanical-systems-based phase change actuator has been developed and tested for high-speed mechanical power output and force generation. This actuator is well suited for a variety of advanced devices like tactile displays or micro fluidic systems. The device features two thin membranes that bound a cavity filled with working fluid. The working fluid boils at low temperature. Two sizes of actuator are tested, an actuator with membrane sidelengths of 5 mm and an actuator with top membrane sidelength of 10 mm. Two top membrane materials are explored consisting of 2 μm thick silicon and 300 nm thick silicon nitride. Heat addition is through the lower membrane which is fabricated with novel capillary structures designed to increase the efficiency of actuator operation. The actuator is shown to produce up to 2.6 mW of mechanical power output and generate an applied force of 43 mN. Operating speeds up to 100 Hz are demonstrated.