Magnetic-field induced asymmetric hydrogel fibers for tough actuators with programmable deformation

Our work develops a class of shape programmable hydrogel fibers with high mechanical strength, which were further designed as soft grippers and intelligent curtains in response to solvents and environment humidity. [Display omitted] •A magnetic-field induction strategy was used to fabricate programmable actuators.•The tough AMFI hydrogel fibers had asymmetric structure.•The AMFI hydrogel fibers exhibited rapid bending velocity in response to solvent.•The AMFI and NMFI hydrogel fibers were designed as soft gripper and smart curtains. Ingenious design of soft actuators with high mechanical performance, rapid actuation, and programmable deformation is necessary for their practical applications in the fields of artificial muscles, smart textiles, and soft robotics. Here we used a facile magnetic-field induction strategy to fabricate programmable actuators composed of tough hydrogel fibers. The anisotropic hydrogel fibers that consisted of dual physically cross-linked networks showed high tensile strength (28.9 MPa), while the asymmetric distribution of magnetic nanoparticles in hydrogel networks endowed the actuators with rapid bending velocity (3.2°·min−1·mm−1) in response to solvents. The pick-and-place manipulation of objects from ethanol to water were demonstrated by using the soft grippers composed of asymmetric hydrogel fibers. Furthermore, smart curtains that were woven by hydrogel fibers automatically rolled up or spread out in response to the change of ambient humidity. This work proved that tough hydrogel fibers fabricated by our magnetic-field induction strategy provided more possibilities in the field of soft actuators.