One-Step\nDigital Light Processing 3D Printing of Robust,\nConductive, Shape-Memory Hydrogel for Customizing High-Performance\nSoft Devices

Mechanically robust and electrically\nconductive hydrogels hold\nsignificant promise for flexible device applications. However, conventional\nfabrication methods such as casting or injection molding meet challenges\nin delivering hydrogel objects with complex geometric structures and\nmulticustomized functionalities. Herein, a 3D printable hydrogel with\nexcellent mechanical properties and electrical conductivity is implemented\nvia a facile one-step preparation strategy. With vat polymerization\n3D printing technology, the hydrogel can be solidified based on a\nhybrid double-network mechanism involving in situ chemical and physical\ndual cross-linking. The hydrogel consists of two chemical networks\nincluding covalently cross-linked poly(acrylamide-<i>co</i>-acrylic acid) and chitosan, and zirconium ions are induced to form\nphysically cross-linked metal-coordination bonds across both chemical\nnetworks. The 3D-printed hydrogel exhibits multiple excellent functionalities\nincluding enhanced mechanical properties (680% stretchability, 15.1\nMJ/m<sup>3</sup> toughness, and 7.30 MPa tensile strength), rapid\nprinting speed (0.7–3 s/100 μm), high transparency (91%),\nfavorable ionic conductivity (0.75 S/m), large strain gauge factor\n(≥7), and fast solvent transfer induced phase separation (in\n∼3 s), which enable the development of high-performance flexible\nwearable sensors, shape memory actuators, and soft pneumatic robotics.\nThe 3D printable multifunctional hydrogel provides a novel path for\ncustomizing next-generation intelligent soft devices.