Polyurethane-based high-performance strain sensor with sliding cyclodextrin molecules

Dissipates stress and stabilizes AgNWs networks via polyrotaxane sliding rings • Achieves 700% strain, GF = 141, and 20,000-cycle stability at 200% strain • Realizes 98% self-healing at 50 °C for 30 min, 13.8 g/(m 2 ·h) air permeability and alkaline degradation • Enables monitoring of human motions for long-term wearable use Flexible resistive strain sensors based on silver nanowires (AgNWs) demonstrate significant potential for wearable electronics and human motion monitoring; however, they face substantial challenges due to severe modulus mismatch and limited cyclic stability under large-amplitude strain. In this context, a sandwich-structured strain sensor was developed based on supramolecular polyurethane functionalized with dynamic polyrotaxane (PR) sliding rings, where the freely mobile α-cyclodextrin units dissipate interfacial stress and stabilize the AgNWs conductive network under repeated stretching. The optimized sensor achieves an ultra-wide operational strain up to 700% and a high gauge factor of 141. Importantly, it maintains a stable resistance response over 20,000 loading-unloading cycles at 200% strain, surpassing all previously reported pristine AgNWs-based counterparts. Additionally, it exhibits 98% mechanical self-healing efficiency at 50 °C within 30 min, along with excellent breathability and alkaline degradability. This research presents a promising strategy for the development of high-performance, sustainable wearable sensing devices.