VO2 Phase-Transition-Based Vertical MEMS Microactuators

A vertical multilayer VO₂ MEMS microactuator device is reported in this work. A 150-nm-thick VO₂ layer is sandwiched between the top Pt and bottom indium tin oxide (ITO) electrodes. An equivalent thermal circuit is developed with a thermal response time of 0.39 ms. With the insulator-to-metal phase transition of VO₂ at ~68 °C accompanied by large electrical and lattice changes, a 35-μmlong VO₂ actuator experiences 2-μm deflection across the phase transition driven by heating and 0.22-μm deflection when electrothermallyactuated.The COMSOL finite element analysis is performed to determine the spatial distribution of the current flow and temperature profile and to verify the experimental measurements of strain-induced bending in this multilayer vertical structure. The obtained experimental result shows a good fit with the simulation analysis, which can in future be used to develop a generic understanding of such vertical MEMS devices.