Tough, Wide-Temperature-Resistant, and Water-Retentive Conductive Hydrogel for Human Motion Sensing

Abstract

Advances in artificial intelligence and the Internet of Things have driven the development of innovative materials for human-machine interfaces, touch panels, and tactile sensors. To meet the performance and functional demands of high-end wearable products, these materials must maintain high conductivity, flexibility, stretchability, and transparency in both low- and high-temperature environments. In this study, we developed an innovative hydrogel, S_xG_y, by copolymerizing acrylamide (AAM), sulfobetaine vinylimidazole (SBVI), and methacrylated lysine (LysMA), combined with dialdehyde-functionalized poly(ethylene glycol) (DF-PEG) and glycerol, where x and y represent SBVI and glycerol content, respectively. This formulation enabled dynamic hydrogen bonding and covalent imine bonds, achieving rapid gelation (under 4 min at room temperature) and producing a stable hydrogel. Experimental results showed that the S_5.0G_0.25 hydrogel performed excellently across temperatures from −20 to 50 °C, exhibiting exceptional toughness (0.562 MJ/m³) at room temperature, retaining 71.5% toughness at −20 °C, and increasing toughness by 210% at 50 °C. It withstood over 500 cycles without significant electrical performance degradation and maintained good transparency across the temperature range. Additionally, the hydrogel demonstrated outstanding water retention, maintaining nearly constant volume for 120 days. This breakthrough positions the hydrogel as a promising material for next-generation wearable sensors and flexible electronics, paving the way for durable, transparent devices in extreme environments.