Hygroresponsive Torsional Yarns and Actuators Based on Cascade Amplification of the Deformation

Fiber-based hygroresponsive torsional actuators provide desirable merits, such as light weight and shapeability, for developing smart systems to harvest energy from moisture which is a ubiquitous natural resource. A key challenge in this development realize moisture-triggered actuation combining large rapid responses. Here, multiscale design strategy explored create high-performance consisting of chitosan multiwalled carbon nanotubes (MWCNTs). The superior performance arises the synergism contributing factors at different scales, including 1) MWNCTs accelerate water transport primary twisted fibers (PTFs), fostering rotation PTFs upon stimuli; 2) situ-formed hierarchically-assembled twists cascade amplification actuation. Specifically, are self-twisted generate secondary helical yarns, that subsequently over-twisted yield tertiary coiled yarn. resultant yarn actuator can reach maximum speed 11 400 rpm 5 s, output gravitational potential 2.4 J kg−1 power 0.053 W during contraction. This work represents first fiber-based by virtue situ formation yarns. established principles will enable toward advanced intelligent textile soft robotics.