Bending in VO2-coated microcantilevers suitable for thermally activated actuators

The curvature of VO2-coated silicon microcantilevers was measured as the temperature was cycled through the coating's insulator-to-metal transition (IMT), which drives the curvature change mainly through the strain generated during this reversible structural transformation. The films were grown by pulsed laser deposition (PLD) on heated substrates. Cantilever tip displacement was measured for a 130 mu m long cantilever as the temperature was changed by recording the deflection of a laser beam, and the curvature change and estimated film stress were calculated from this data. A change in curvature of over 2000 m(-1) was observed through the narrow temperature range of the IMT, with a maximum rate of similar to 485 m(-1) per degree. Estimated recoverable stress was similar to 1 GPa through the transition region. These results suggest applications in actuator devices with reduced dimensions, including submicron lengths, multifunctional capabilities, and possibly with higher operational frequencies than other thermally actuated devices. (C) 2010 American Institute of Physics. [doi:10.1063/1.3369282]