Magnetic Field Assisted Fabrication of Asymmetric Hydrogels for Complex Shape Deformable Actuators

Hydrogel actuators exhibit various motions such as contraction, expansion, bending, and rotation in response to external stimuli, which are of potential applications in artificial muscles, photonic displays, and soft manipulators. However, it remains a challenge to fabricate hydrogel actuators with complex deformation through a facile pathway. Herein, we report that hydrogel actuators with asymmetric structure were rapidly fabricated by magnetic inducement and subsequent in situ polymerization. The asymmetric hydrogel actuators could deform in acidic solution and reversibly recover in alkaline solution. Importantly, the programmable deformations of hydrogel actuators could be achieved by introducing complex patterns into hydrogel networks through prearranged magnets. The patterned hydrogel was demonstrated for the application as the switch in an electric circuit. This work provided a facile, fast, and universal strategy to fabricate programmable hydrogel actuators with asymmetric structures.