Self-Repairing, Large Linear Working Range Shape Memory Carbon Nanotubes/Ethylene Vinyl Acetate Fiber Strain Sensor for Human Movement Monitoring

Flexible strain sensors have shown great application value in wearable devices. In the past decades, researchers have spent numerous efforts on developing high-stretchability, excellent dynamic durability, and large linear working range flexible strain sensors and shaped a series of important research results. However, the viscoelasticity of the elastic polymer is always a big challenge to develop a flexible sensor. Here, to overcome this challenge, we developed a novel self-repairing carbon nanotubes/ethylene vinyl acetate (CNTs/EVA) fiber strain sensor prepared by embedding the CNTs on the surface of the swollen shape memory EVA fiber via the ultrasonic method. The CNTs/EVA fiber strain sensors responded with significant results, with high stretchability (190% strain), large linear working range (up to 88% strain), excellent dynamic durability (5000 cycles), and fast response speed (312 ms). In addition, the permanently damaged conductive network of the strain sensors, caused by the viscoelasticity of elastic polymer, can restore above the transforming temperature of the shape memory CNTs/EVA fiber. Moreover, the performance of the restored strain sensors was almost as same as that of the original strain sensors. Furthermore, human health monitoring tests show that the CNTs/EVA fiber has a broad application prospect for human health monitoring in wearable electronic devices.