Tough and Self‐Adhesive Nanolignin Multifunctional Hydrogel‐Based Strain Sensor for HumanMachine Interaction

Conductive hydrogels are crucial to intelligent robotics and wearable devices, but their adoption is hindered by limited functionality and energy-intensive petrochemical synthesis. To address this challenge, a nanolignins (NLs)-reinforced polyacrylamide hydrogel (NL@PAM) was prepared via a green strategy at room temperature. Lignin nanoparticles were synthesized by a green method and integrated into the polyacrylamide network through extensive hydrogen bonding and interchain interactions. This structure imparts the NL@PAM hydrogel with a unique combination of mechanical and functional properties, including high tensile strength (1.32 MPa), ultrahigh stretchability (1880%), strong self-adhesion (196 kPa), and high ionic conductivity (13.96 mS cm^-1). As a demonstration, the hydrogel was used as a wearable sensor on human fingers; it converted real-time finger movements into control signals for a robotic arm, which faithfully replicated the gestures. These results demonstrate a high-performance multifunctional hydrogel and establish a sustainable paradigm for soft electronics, leveraging green chemistry and renewable biomass for future intelligent systems.