Direct 4D printing of functionally graded hydrogel networks for biodegradable, untethered, and multimorphic soft robots

Abstract

Highlights The binder jetting method for the 4D printing of soft robots has been developed. Compositionally graded cross-linking agents gradually form stable porous network structures that enable programmable hygroscopic deformation. A multi-stimuli-responsive and untethered soft robot with stark stimulus selectivity has been developed using the systematic bed design incorporating additional functional agents. The biodegradability of the soft robot has been confirmed with degradation rates of 96.6% within 72 h.