3D printed silk fibroin-based hydrogels with tunable adhesion and stretchability for wearable sensing

Abstract

Hydrogel-based wearable strain sensors have recently gained considerable interest due to their promising applications in real-time health monitoring and motion detection. However, achieving integrated high-stretchability, self-adhesiveness, and long-term water-retaining property simultaneously in hydrogel systems remains a big challenge, which limits their applications in wearable electronics. Herein, a multifunctional hydrogel material designed is proposed for wearable strain sensors that can be manufactured by digital light processing (DLP) 3D printing technology. By tailoring the composition of chemically cross-linked networks (ploy(acrylamide)/poly(acrylic acid)/poly(ethylene glycol) diacrylate), physically cross-linked networks (ploy(acrylamide)/poly(acrylic acid)/poly(ethylene glycol) diacrylate/silk fibroin/glycerol/water) and microstructures on the surface, the 3D printed hydrogel exhibits promising superior and adjustable mechanical properties, tunable adhesion and good water-retaining property simultaneously. In addition, through adding conductive ions, high ionic conductivity can also be achieved for stretchable sensing applications. Based on these integrated multifunctionalities, the 3D printed hydrogel is suitable for wearable strain sensors to detect various body motions. This work provides a prospect for 3D printable hydrogel systems with broad applications in wearable electronics.