Research On Stimuli-responsive Deformable Liquid Crystal Elastomer Fibers And Functional Devices

Liquid-crystal-elastomer(LCE)capable of reversible,large-scale,programmable deformation in response to external stimuli have great potential in many applications,including artificial muscles,soft robotics,micromechanical systems,sensors,microfluidics and wearable devices.Despite their exciting prospects,limitations-such as few modes of shape transformation in a single actuator due to limited degree of freedom(DOF),difficulty to concurrently gain large length change and powerful stress,lack of scalable manufacturing method seriously restrict their engineering applicability.Inspired by the spiral formation mechanism of plant tendrils,we design and prepared bioinspired self-winding LCE fiber actuators that possess diverse controllable shape transformations(bending,twisting,coiling,and shortening),a combination of high contraction ratio(1750%)and high stress(～3.4 MPa),long term photomechanical robustness(over 1000 photodeformation cycles without obvious fatigue),and readily,scalable manufacture.LCE fiber actuators can simultaneously conduct two or three kinds of deformation and thus enables complex morphing behaviors to manipulate objects(grabbing,dragging,lifting,and winding),and even drive gear set.We envision that these self-winding fiber actuators combined with high DOF,tunable actuation,photomechanical robustness,and mass production could be developed as highperformance artificial muscles for broad engineering applications.Based on the high DOF of LCE fiber actuators and their excellent optomechanical properties,we create a phototunable self-oscillating system that possesses a broad range of oscillation modes,controllable evolution between diverse modes,and loading capability.It enables not only controllable generation of three basic self-oscillations but also the production of diverse complex oscillatory motions.Moreover,it can work continuously over 1270000 cycles without obvious fatigue,exhibiting high robustness.We envision that this system with controllable self-oscillations,loading capability,and mechanical robustness will be useful in autonomous,self-sustained machines and devices with the core feature of photo-mechanical transduction.Based on liquid crystal elastomer fibers,we have developed a new processing method for three-dimensional flexible actuators.The method is divided into two steps:the first step is to prepare liquid crystal elastomer fibers by a mold method,and the oriented liquid crystal elastomer fibers are used as the basic assembly unit.In the second step,liquid crystal elastomer fibers are assembled into liquid crystal elastomer actuators with various three-dimensional structures through fiber weaving.Using a variety of programming methods,not only tubular actuators with multiple deformation modes,but also multi-functional responsive LCE actuators with complex shapes can be obtained.Tubular LCE actuators can not only transport and control fluids,but also act as soft robots with powerful transport capabilities.Tubular actuators with multimodal actuation and programmable shape transformation can provide potential solutions for the design of microfluidics,medical devices,and soft robotics.