Recyclable Wearable Sensor Based on Tough, Self-Healing, Adhesive Polyurethane Elastomer for Human Motion Monitoring

Abstract

Although some progress has been achieved in flexible strain sensors, it is still a big challenge to develop sensors with excellent self-healing capability, adhesive, and recyclable properties for enhanced lifespan, facile operation, and decreased waste pollution in the flexible electronic field. In this study, we successfully synthesized the pyrene-terminated multifunctional polyurethane elastomer called PMFPU based on dynamic covalent bond and noncovalent hydrogen bonds, which integrates exceptional tough mechanical properties (the tensile toughness of 168.4 MJ/m3), excellent self-healing performance (healing efficiency of 96%), superior adhesive property (shear strength as high as 1.46 MPa), and well-performed reprocessability (more than five cycles). Furthermore, we applied PMFPU in the fabrication of stretchable strain sensors based on the π–π stacking interactions between pyrene in PMFPU and carbon nanotubes (CNTs). Based on this unique design, the obtained flexible sensors can dissolve in THF and DMF solvents, enabling the reprocessing ability and avoiding electronic waste pollution. The stretchable strain sensors could detect human movements and facial expressions. Moreover, the sensors can restore stable sensing capabilities even after a repaired process or recyclable process, which is of significant importance for the development of environmentally friendly and high-performance sensors. The fabrication of these functional sensors holds broad application prospects in fields such as medical monitoring, human–machine interaction, and electronic skin.