Bio-Inspired Stimuli-Responsive Ti₃C₂T_x/PNIPAM Anisotropic Hydrogels for High-Performance Actuators

Near-infrared (NIR) light-responsive hydrogels have the advantages of high precision, remote control and excellent biocompatibility, which are widely used in soft biomimetic actuators. The process by which water molecules diffuse can directly affect the deformation of hydrogel. Therefore, it remains a serious challenge to improve the response speed of hydrogel actuator. Herein, an anisotropic photo-responsive conductive hydrogel is designed by a directional freezing method. Due to the anisotropy of the MXene-based PNIPAM/MXene directional (PMD) hydrogel, its mechanical properties and conductivity are enhanced in a specific direction. At the same time, with the presence of the internal directional channels and the assistance of capillary force, the PMD hydrogel can achieve a volume deswelling of 70% in 2 s under light irradiation, further building a hydrogel actuator with a fast response performance. Additionally, the hydrogel actuator can lift an object 40 times its weight by a distance of 6 mm, realizing the advantages of both rapid responsiveness and high driving strength, which makes the hydrogel actuator have important application significance in remote control, microflow valve, and soft robot.