Poly(Ionic Liquid)/Silk Fibroin Conductive Hydrogels with Intrinsic Antifreezing and Water Retention Properties for Multimodal Sensing and Human–Machine Interaction

Ionic conductive hydrogels have garnered considerable attention as flexible wearable sensors due to their intrinsic flexibility and tailorable properties. However, their practical applications have been significantly limited by poor water retention capability, insufficient antifreezing performance, limited conductivity, and inadequate sensing sensitivity. Herein, we report an ionic conductive hydrogel fabricated by introducing silk fibroin (SF) and lithium bromide (LiBr) into a poly(ionic liquid) (PIL) network via a one-step electron beam irradiation strategy. Benefiting from the synergistic effect of the PIL and LiBr, the resulting hydrogel exhibits exceptional freezing resistance (<−60 °C) and remarkable water retention (>92% after 30 days). The flexible strain sensor based on the obtained hydrogel exhibits excellent cyclic stability, enabling real-time and accurate monitoring of human joint motion as well as gesture-based robotic hand control through human–machine interaction. Furthermore, multiple hydrogel sensors can be integrated into a soft sensor array for tracking tactile trajectories and detecting spatial pressure distribution, and can also serve as a writing sensor to transmit handwriting information. Notably, the as-prepared hydrogel displays outstanding temperature sensitivity within the 30–40 °C range, achieving a temperature coefficient of resistance as high as −3.63%/°C. This study provides an effective strategy for the design of high-performance hydrogels and underscores their broad prospects in the field of human–machine interactive wearable and flexible electronics.