Polyvinyl Alcohol/Silk Fibroin/Borax Hydrogel Ionotronics: A Highly Stretchable, Self-Healable, and Biocompatible Sensing Platform.

The emergence of hydrogel ionotronics has significantly extended the applications of soft electronics by allowing intimate interfaces between electronic units and biological/engineered surfaces for better sensing and communication with surrounding stimuli. However, hydrogel ionotronic devices that combine high stretchability, self-healing, good water retention, and biocompatibility are still desired. Here, we report a biocompatible ionic hydrogel made of polyvinyl alcohol, silk fibroin, and borax. In this ionic hydrogel, polyvinyl alcohol and borax offer the high stretchability and conductivity, respectively, while silk fibroin improves the stability of the hydrogel and increases water uptake by the gels. The hydrogel features strain larger than 5000%, good water retention, self-healing, and tunable conductivity and adhesive capabilities. We also demonstrate the use of the hydrogel as a sensing platform to monitor human body motion for applications in health management, soft robotics, and human-machine interfaces.