High Performance and Multifunction Moisture‐Driven Yin–Yang‐Interface Actuators Derived from Polyacrylamide Hydrogel

Abstract

High actuation performance of a moisture actuator highly depends on the presence of a large property difference between the two layers, which may cause interfacial delamination. Improving interfacial adhesion strength while increasing the difference between the layers is a challenge. In this study, a moisture‐driven tri‐layer actuator with a Yin–Yang‐interface (YYI) design is investigated in which a moisture‐responsive polyacrylamide (PAM) hydrogel layer (Yang) is combined with a moisture‐inert polyethylene terephthalate (PET) layer (Yin) using an interfacial poly(2‐ethylhexyl acrylate) (PEA) adhesion layer. Fast and large reversible bending, oscillation, and programmable morphing motions in response to moisture are realized. The response time, bending curvature, and response speed normalized by thickness are among the best compared with those of previously reported moisture‐driven actuators. The excellent actuation performance of the actuator has potential multifunctional applications in moisture‐controlled switches, mechanical grippers, and crawling and jumping motions. The Yin–Yang‐interface design proposed in this work provides a new design strategy for high‐performance intelligent materials and devices.

MXene-Based Soft Humidity-Driven Actuator with High Sensitivity and Fast Response

“…When water vapor is applied to the left side of the actuator, the left side absorbs more water molecules, causing it to expand and bend inward into an arc. This asymmetry causes the left edge to have a greater interaction force with the substrate than the right edge, 41 acting as a fulcrum that propels the actuator to the right, causing its movement in that direction. Notably, the soft crawler actuator can autonomously move forward a certain distance without the need for a humidity switch, contingent on the humidity gradient established by the water droplets.…”