"All-in-one" ink for light-based 4D printing of conducting, tough, anti-freezing, and cytocompatible hydrogels.

[Display omitted] • Novel photopolymerizable ink formulations based on conducting polymer were prepared. • DLP-based-3D printing of the formulation yields multi-functional hydrogels. • 3D-printed gels are mechanically robust and electrically conductive. • Printed gels resist freezing and maintain conductivity at sub-zero temperatures. • Gradient crosslinking of printed gels induces shape-morphing behavior. High-performance hydrogel-based electronic devices require conducting hydrogels. Conducting hydrogels that are stretchable, soft, and biocompatible are in much demand to fabricate human–machine interfaces, wearable devices, soft robotics, and many other applications. We present a new generation polymeric formulation to prepare hydrogels by digital light processing (DLP)-based three-dimensional (3D) printing technology with visible light that are anti-freezing, electrically conductive, tough, stretchable, and non-toxic. The printed conducting hydrogels have exceptional water-holding capability at atmospheric conditions and tolerance to freezing over a wide range of temperatures from − 80 to 45 °C. The inks are amenable to the manufacturing of four-dimensional (4D)-printed hydrogels that can elicit pre-programmed structural deformations. This work presents polymeric formulations for potentially designing ultrafast programmable electronic devices with printed hydrogel electronics in various biomedical applications, soft robotics, biosensors, flexible electronics, human–machine interfaces, and health monitors for use under extreme environmental conditions. [ABSTRACT FROM AUTHOR]