SU-8 chevron electrothermal micro-actuator with three-layer structures

To eliminate the out-of plane actuation of a SU-8 electrothermal micro-actuator,a novel SU-8 chevron electrothermal micro-actuator with a copper/SU-8/copper symmetrical structure was proposed.The mechanical model of the micro-actuator which contains the stiffness of a driven structure was established by using the stiffness matrix method.The geometric parameters of the micro-actuator were designed for a microgripper by using the established model.The designed micro-actuator was simulated by Ansys software and the simulation results verified the reasonability of the mechanical model.Then,the micro-actuator and the microgripper were fabricated by a simple process followed with a performance test.The test results show that when the temperature of the micro-actuator only increases 32.93℃ in a driving voltage of 150 mV,the output displacement is 2.5 μm and jaw gap change is 126 μm.During the operation processes,the out-of plane displacement of the tip is always lower than 500 nm.Finally,the micro-manipulation sequence of a SU-8 micro-part with a size of 1.4 mm×135 μm×50 μm was carried out to verify the driving ability of the micro-actuator.