A two-way membrane-type micro-actuator with continuous deflections

This paper presents design, simulation, fabrication, and testing of a novel two-way micro-membrane actuator able to deflect in both upward and downwar d directions with continuous deflections. The design concept, to realize tw o-way continuous movement, is achieved by arranging different bimorph struc tures at different regions of the actuator with two kinds of boundary condi tions. The actuator comprises of a square membrane with four bimorph beams and one central bimorph plate on it. The material (e.g. aluminum) on the to p layer of the bimorph beams and plate has a larger thermal expansion coeff icient than the material (e.g. silicon dioxide) of the membrane. The drivin g voltages in the two operating modes are both less than 3.5 V at about 350 mW maximum power consumption for an 1 mm(2) membrane actuator. The upward and downward deflections achieved up to 50 and 15 mu m with maximum simulat ed temperatures less than 420 and 150 degrees C, respectively. A finite-ele ment model is built to simulate the thermal mechanical behaviors that are c ompared with the experimental results. The design parameters influencing th e deflections of the actuator are also discussed.