Highly stretchable hydrogels for sensitive pressure sensor and programmable surface patterning by thermal bubble inkjet technology

Hydrogels with tough strength, programmable deformation are crucial for their practical applications. In this work, we reported the preparation and the programmable shape deformations of highly stretchable hydrogel. The graphene oxide/polyacrylamide/sodium alginate composite hydrogel was prepared, its microstructure and mechanical properties were studied. An aqueous calcium solution was selectively printed onto the hydrogel surfaces using an inkjet printer, resulting in programmable deformation of the composite hydrogel by creating regions of swelling/deswelling when subjected to external stimulations. Next, we fabricated a pressure-capacitance hydrogel sensor to demonstrate its application. Furthermore, the deformation rate and extent of the hydrogels can be controlled by adjusting the printing pattern position, number, length, and calcium solution concentration. Finally, several complex 2D and 3D shapes were fabricated by printing appropriate patterns on one or both surfaces of the hydrogel sheets.