Helical TPU/Ag@K2Ti4O9 fibers with shape memory performance for highly stretchable and sensitive strain sensors

Even though wearable electronics based on e-textiles have been attracting increasing attention, their unsatisfactory durability has significantly impeded their practical applications. In this regard, thermoplastic polyurethane (TPU)/Ag@K2Ti4O9 composite fibers with excellent mechanical properties and conductivity along with outstanding durability have been successfully prepared via wet-spinning in this work. However, it still has some shortcomings, such as a high modulus mismatch with skin, and slow resistance recovery after stretching when applied to human sensing. Therefore, helical fibers have been further developed, which are sturdy and do not bring any uncomfortably wearable electronics (the fracture stress is greater than 0.4 N and an elongation of 50% can be achieved under only 0.01 N with a 40% increased resistance). The resultant helical composite fiber has stable sensing performance under 100% strain, with a gauge factor (GF) up to 0.8–1.5. In particular, it can quickly recover its original length and resistance in hot water or under an infrared lamp due to the thermal shrinkage effect of PU when it breaks under destructive overstretch (greater than 300% strain). This durable, repairable, and cost-effective helical fiber can provide new insights into the design and promotion of fibrous human-computer interaction components.