Hybrid Zwitterionic Hydrogels with Encoded Differential Swelling and Programmed Deformation for Small-Scale Robotics

This work introduces a zwitterionic/acrylate hybrid hydrogel system with encoded differential swelling and anisotropic elasticity for programmable deformation in small-scale soft robotics. By combining 3-dimethyl(methacryloyloxyethyl) ammonium propanesulfonate (DMAPS) and methacrylic acid (MAA) in tunable ratios, the researchers achieved hydrogels exhibiting reversible expansion or contraction in response to ionic strength, along with self-healing and mechanical adaptability. These materials were tessellated into hybrid constructs that transform predictably from 2D to 3D shapes (rolling, buckling, or spiraling) upon salinity changes, enabling untethered robotic functions such as cargo gripping, magnetic navigation, and controlled release. The study establishes a ‘molecule-to-robot’ framework for designing biocompatible, programmable hydrogel actuators for biomedical microrobotics.