Bidirectional micro-actuators based on eccentric coaxial composite oxide nanofiber

It is of great importance to develop new micro-actuators with high performance by optimizing the structures and materials. Here we develop a VO₂/Al₂O₃/CNT eccentric coaxial nanofiber, which can be potentially applied as a micro-actuator. The specific eccentric coaxial structure was efficiently fabricated by conventional thin film deposition methodology with individual CNT templet. Activated by thermal and photothermal stimuli, the as-developed actuator delivers a bidirectional actuation behavior with large amplitudes and an ultra-fast response, ~ 2.5 mS. A tweezer can be further made by assembling two such nanofibers symmetrically onto a tungsten probe. Clamping and unclamping can be realized by laser stimulus. More experimental and simulation investigations indicated that the actuation behaviors could be attributed to the nanostructured eccentric coaxial geometry, the thermal coefficient mismatch between layers and the fast phase transition of VO₂. The micro-actuators will have potentials in micro manipulators, nanoscaled switches, remote controls and other autonomous systems. Furthermore, a large variety of coaxial and eccentric coaxial nanofibers with various functions can also be developed, giving the as-developed methodology more opportunities.