Antiswellable, Conductive, and Recyclable Coacervate Polyacrylamide/Tannic Acid Composite Hydrogel for Underwater Wearable Sensors

Hydrogel-based sensors have attracted increasing attention as fascinating materials for various applications in biomedicine and bioelectronics. However, the application of strain sensors underwater remains a great challenge due to the swelling of hydrogels in an aqueous environment. Herein, we report a coacervate conductive polyacrylamide/tannic acid (PAM/TA) composite hydrogel with strong antiswellable properties. The PAM/TA composite hydrogel exhibits a good electrical performance, where the conductivity is found to be 2.7 × 10–4 S/cm, which is stable during recycling, with an excellent stretchability of 1000% at a tensile strength of 1.5 MPa. The composite hydrogel shows excellent biocompatibility and antiswellable behavior and maintains long-term stability underwater to monitor human movements. In addition, the environmentally friendly composite hydrogel can be recycled repeatedly. The PAM/TA composite hydrogel with excellent antiswelling and stability, good electrical performance, and remarkable stretchability has great potential for the applications as underwater wearable sensors.