Programmable multi-stimulus-responsive Shape-Morphing Hydrogels for Small-Scale Robotics

Stimulus-responsive hydrogels have attracted significant attention as a versatile class of soft actuators. Introducing anisotropic properties and shape-change programmability to responsive hydrogels promises a host of opportunities in the development of soft robots. Herein, we report the synthesis of two classes of hydrogel nanocomposite systems with multimodal stimulus-response and with predetermined microstructural anisotropy and shape transformation. Our hydrogel nanocomposites contain asymmetric cellulose nanocrystals. The shear-induced alignment of cellulose nanocrystals provides the hydrogels with anisotropic swelling and mechanical properties. We believe the proposed material systems introduce a powerful toolbox for the development of future generations of biomedical soft robots, especially in confined biological environments where the delivery of functional medical devices is challenging.