The Applied Materials Group (AMG) is focused on the integration of novel smart materials into micrometer-sized devices. Our main emphasis has been on vanadium dioxide (VO2) thin films. VO2 exhibits a solid-solid phase change, which can be thermally induced at a temperature of ~ 68 °C. During this phase transition, the material goes through an electronic/structural transformation (Mott-Peierls type) during which many of the material properties (e.g. electrical, optical, mechanical) change abruptly. The multifunctional properties of VO2, the relative proximity of its transition temperature to room temperature, and its intrinsic hysteretic behavior – which gives the material memory capabilities – make this material very attractive for practical applications.
Given the repeatability, large strain energy density, robustness, and inherent multifunctionality that VO2 brings to MEMS actuators, these devices are expected to replace currently used actuation technologies. VO2 thin films have successfully been integrated on MEMS actuators. Our VO2-based micromechanical actuators can oscillate at frequencies around 1 kHz – which is considerably fast for a thermal-based actuation process – while sustaining their large vibration amplitudes. The abrupt changes in VO2’s optical properties, and its inherently hysteretic behavior has also been used to program and project near infrared (NIR) images.