Stretchable, Antifreeze,and Water-Retaining SilkFibroin-Based Ionic Conductive Hydrogel for Wearable Sensors

Abstract

Silk fibroin shows great potential for epidermal electronics and implantable medical devices due to its excellent biocompatibility. However, its practical application as a hydrogel is limited by poor mechanical properties, low water retention, and freezing susceptibility. To address these challenges, we developed a composite ionic conductive hydrogel (SF-PAM) from polyacrylamide and silk fibroin. This material exhibits outstanding mechanical performance with an elongation rate of 1663%, a tensile strength of 0.38 MPa, and a toughness of 12.58 kJ m^–2, alongside excellent biocompatibility. Enhanced by lithium ions and sodium carboxylate pyrrolidone, SF-PAM achieves remarkable water retention (90% after 30 days) and antifreeze capabilities (unfrozen at −70 °C). A strain sensor made from SF-PAM demonstrates a wide detection range of 1 to 1200%. Additionally, we integrated this sensor into a smart cart, enabling a wearable electronic skin system that allows precise control through finger movements detected by a smart glove, significantly improving motion monitoring and user experience in wearable technology.