Bio-Inspired Bicomponent Fiber with Multistimuli Response to Infrared Light and Humidity for Smart Actuators

Smart actuators with multistimuli synergistic response functions can be widely used in complex environments. In this study, a torsion side-by-side sodium alginate-sodium alginate/graphene oxide (SA-SA/GO) fiber-based smart actuator with an intermittent spiral structure is reported by the side-by-side wet spinning and twisting methods. With the excellent humidity response of SA and the photothermal properties of GO, the side-by-side fiber can produce a twisting motion of 449 rpm and untwisting rotation motion of 201 rpm at full speed when stimulated by infrared (IR) light (0.5 W/cm2) or moisture (90% RH). Meanwhile, due to the unique bicomponent intermittent spiral structure of the side-by-side fiber, the SA component and the SA/GO component in the spiral structure show different response speeds to infrared light and humidity stimulus, and the actuator can complete a controllable and programmable "forward–stagnation–reverse" synergistic drive response behavior under the co-stimulation of IR light and humidity using the alternating transformation of torque force and solvation force. In addition, owing to the excellent flexibility and synergistic responsiveness of the side-by-side SA-SA/GO smart actuator, it can be prepared to form a series of programmable smart devices for the design of bionic muscles and multifunctional load devices in complex environments, which has important applications in future smart device development.