Graphene‐Doped Hydrogels with Enhanced Conductivity and Stretchability for All‐Weather Wearable Devices

Abstract Conductive hydrogels with high water content, excellent adhesion, and mechanical flexibility have garnered significant attention for flexible and wearable electronic applications. Despite advancements, achieving hydrogels with robust electrical and mechanical properties under extreme environmental conditions remains a key challenge. In this study, a cost‐effective, lignin‐tannin nanosphere graphene‐doped hydrogel (LTGH) synthesized by dispersing graphene within the hydrogel matrix via self‐assembled sodium lignosulfonate and tannic acid nanospheres is presented. The LTGH exhibits exceptional electrical conductivity (28 S m⁻¹), ultra‐high sensitivity (maximum gauge factor ≈350), and an ultra‐low detection limit (<0.5%). Additionally, it demonstrates outstanding stretchability (>1800%), strong adhesion (>50 kPa), UV resistance, and antibacterial properties. By incorporating ethylene glycol, the LTGH maintains reliable performance across a wide temperature range (−80 to 50 °C). Furthermore, the LTGH is successfully integrated into a convolutional neural network‐based sign language recognition system, achieving a compact and lightweight design with high recognition accuracy, rapid responsiveness, and cost efficiency. This work highlights the superior sensing capabilities of graphene‐doped conductive hydrogels, underscoring their potential in all‐weather wearable technologies.