Thermal bubble powered microactuators

Thermal bubble powered micro mechanical actuators have been successfully demonstrated in working liquids. Micro mechanical plates which function as the mechanical actuators are 70×60×2 m³ in size. They have been fabricated by surface-micromachining technology and suspended 2 m above the substrate by the supports of cantilever beams. Micro thermal bubbles which are generated by heavily phosphorus doped polysilicon line resistive heaters have been used to lift the mechanical plates in a controllable manner. The typical current required to generate a single, spherical thermal bubble as the actuation source on top of the micro line resistors (60×2×0.3 m³ in size) is 8.4 mA (80 m Watt) in FC 43 liquid (an inert, dielectrical fluid available from the 3M company). The thermal bubbles have been demonstrated to actuate the mechanical plate perpendicularly to the substrate with a maximum elevation distance of 140 m and a maximum actuation force of 2 N. This new actuation mechanism is expected to find applications for micro fluidic devices.The authors would like to thank Prof. V.P. Carey, Mechanical Engineering department, U.C. Berkeley and Dr. A.P. Lee for valuable discussions. The devices were fabricated in the UC Berkeley Microfabrication Laboratory and the FC liquid was provided by 3M company. This work has been supported by Berkeley Sensor and Actuator Center, an NSF/Industry/University Co-operative Research Center.