Multimaterial cryogenic printing of three dimensional soft hydrogel machines

        The Paper of the Day presents a multimaterial cryogenic printing (MCP) technique that can fabricate sophisticated soft hydrogel machines with accurate yet complex architectures and robust multimaterial interfaces. The MCP technique utilizes an all-in-cryogenic solvent phase transition strategy, involving instant ink solidification followed by in-situ synchronous solvent melting and cross-linking. This allows the fabrication of various multimaterial 3D hydrogel structures with high aspect ratio complex geometries. The authors demonstrate the capabilities of this technique by designing and manufacturing all-printed all-hydrogel soft machines, including self-sensing biomimetic heart valves and untethered multimode magnetic turbine robots.