Silk fibroin-based conductive and antibacterial hydrogels with a dual network for flexible sensors

The flexible wearable hydrogel strain sensors for human motion monitoring have attracted broad attention. However, developing a high-strength hydrogel strain sensor remains challenging and achieves synergistic characteristics such as biocompatibility, antibacterial activity, and conductivity. This work proposes a two-step UV polymerization method for the preparation of (hydrolyzed silk fibroin (HSF)/polyacrylamide (PAM)/polyacrylic acid (PAA)/poly sulfobetaine methacrylate (PSBMA) composite hydrogels. The monomers AM and AA undergo self-polymerization and copolymerization. Meanwhile, SF is cross-linked with them via multiple hydrogen bonds to form the first network. After the second UV initiation, SBMA polymerizes to create the second network. The HSF 8% /PAM/PAA/PSBMA 2% possesses superior tensile strength (1.49 ± 0.07 MPa) and compressive modulus (21.47 ± 1.07 MPa at 99% strain). The SBMA (4 wt%) endows hydrogels with antibacterial activity (98.53% ± 4.93%). The H + ionized by PAA and the ion channels constructed by SBMA (4 wt%) provide hydrogel with ionic conductivity (0.950 S m −1 ). The hydrogel could be used as a flexible strain sensor to monitor human joint activity. The natural silk fibroin allows the hydrogel to retain degradability. Therefore, the SF-based conductive hydrogel shows the potential application in flexible strain sensors.