Skin-inspired healable gradient MXene nanocomposites for flexible ultrawide-range ultradurable sensing electronics with intelligent sign language recognition

Wearable electronics exhibit revolutionary prospects in real-time personalized motion tracking and intelligent human-machine interfacing. However, the development of wearable electronics capable of sensing across a broad pressure range with rapid responsiveness and long-term reliability remains a formidable challenge. Herein, inspired by tactile sensing enabled by the gradient moduli structure of human skin, a gradient-moduli healable waterborne polyurethane (H-WPU)/MXene elastomer nanocomposite was fabricated through solvent evaporation-induced gradient sedimentation of the assembly of H-WPU emulsion particles and conducting MXene nanosheets, and subsequent H-WPU emulsion particles' polymer chain interdiffusion. The healable gradient-moduli H-WPU/MXene elastomer nanocomposite demonstrates excellent mechanical and self-healing performance, including a high tensile strength, an exceptional strain, and a remarkable healing efficiency. When the gradient-moduli elastomer nanocomposite is integrated with the interdigitated electrode, the as-fabricated flexible sensor exhibits an ultrabroad sensing range up to 1250 kPa, rapid response/recovery times (10/8 ms), and outstanding durability over 100,000 loading/unloading cycles. In addition to the high-pressure motion monitoring, the sensor enables precise capture of subtle physiological signals (radial artery pulse, jugular venous pulse, respiration), and when coupled with machine learning, 99.7% accuracy in American Sign Language recognition is achieved, highlighting its promising applicability in intelligent human-machine interface and personalized health monitoring.