Recyclable Wearable\nSensor Based on Tough, Self-Healing,\nAdhesive Polyurethane Elastomer for Human Motion Monitoring

Abstract

Although some progress has been achieved in flexible\nstrain sensors,\nit is still a big challenge to develop sensors with excellent self-healing\ncapability, adhesive, and recyclable properties for enhanced lifespan,\nfacile operation, and decreased waste pollution in the flexible electronic\nfield. In this study, we successfully synthesized the pyrene-terminated\nmultifunctional polyurethane elastomer called PMFPU based on dynamic\ncovalent bond and noncovalent hydrogen bonds, which integrates exceptional\ntough mechanical properties (the tensile toughness of 168.4 MJ/m³), excellent self-healing performance (healing efficiency\nof 96%), superior adhesive property (shear strength as high as 1.46\nMPa), and well-performed reprocessability (more than five cycles).\nFurthermore, we applied PMFPU in the fabrication of stretchable strain\nsensors based on the π–π stacking interactions\nbetween pyrene in PMFPU and carbon nanotubes (CNTs). Based on this\nunique design, the obtained flexible sensors can dissolve in THF and\nDMF solvents, enabling the reprocessing ability and avoiding electronic\nwaste pollution. The stretchable strain sensors could detect human\nmovements and facial expressions. Moreover, the sensors can restore\nstable sensing capabilities even after a repaired process or recyclable\nprocess, which is of significant importance for the development of\nenvironmentally friendly and high-performance sensors. The fabrication\nof these functional sensors holds broad application prospects in fields\nsuch as medical monitoring, human–machine interaction, and\nelectronic skin.