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

Abstract

This paper presents design, simulation, fabrication, and testing of a novel two-way micro-membrane actuator able to deflect in both upward and downward directions with continuous deflections. The design concept, to realize two-way continuous movement, is achieved by arranging different bimorph structures at different regions of the actuator with two kinds of boundary conditions. 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 top layer of the bimorph beams and plate has a larger thermal expansion coefficient than the material (e.g. silicon dioxide) of the membrane. The driving 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 simulated temperatures less than 420 and 150 degrees C, respectively. A finite-element model is built to simulate the thermal mechanical behaviors that are compared with the experimental results. The design parameters influencing the deflections of the actuator are also discussed.