Repairable, Recyclable and High‐Performance Flexible Strain Sensors

ABSTRACT Flexible wearable devices, especially strain sensors, have attracted extensive attention in recent years due to their promising applications in health monitoring and human‐machine interaction. However, most reported flexible strain sensors could not be repaired/healed or recycled, which is vital for their long‐term use and a sustainable society. Furthermore, their existing fabrication process often requires expensive raw materials and complex techniques. Here, we develop high‐performance flexible strain sensors with both repairable and recyclable capacity, by simply hot‐pressing highly electroconductive carbonized silk fabric (CSF) into the surface of exchangeable polyurethane (xPU). The obtained CSF‐xPU strain sensors show a large workable strain range (> 80%), fast response (< 60 ms), high sensitivity, and excellent durability. Moreover, the sensors could also be efficiently repaired/healed and recycled based on the dynamic carbamate bonds in the xPU. Due to the abundant source of silk fabric and large‐scale production of polyurethane, as well as the simple hot‐pressing process to composite the CSF and the xPU, this CSF‐xPU strain sensor is low‐cost. Therefore, the repairable/healable and recyclable strain sensors here show great potential as high‐performance and sustainable wearable devices for practical applications.