Highly\nSensitive and Stretchable Polyurethane Fiber\nStrain Sensors with Embedded Silver Nanowires

Abstract

Flexible\nstrain sensors have attracted a great amount of attention\nfor promising applications in next-generation artificially intelligent\ndevices. However, it is difficult for conventional planar strain sensors\nto meet the requirements of miniature size and light weight for flexible\nelectronics. Herein, a highly sensitive and stretchable fiber strain\nsensor with a millimeter diameter was innovatively fabricated by the\ncapillary tube method to integrate silver nanowires (AgNWs) in polyurethane\n(PU) fibers. Scanning electron microscopy results demonstrate that\nAgNWs were embedded into the surface layer of PU fibers and formed\ncompletely conductive networks. The unique AgNW networks endow the\nPU/AgNW fibers with superior electrical conductivity of 3.1 S/cm,\nhigh elongation at break of 265%, wide response range of 43%, high\ngauge factor of 87.6 up to 22% strain, fast response time of 49 ms,\nand excellent reliability and stability. Such satisfactory stretchability\nand sensitivity is attributed to the combination of the highly stretchable\nPU matrix and the embedded architecture of the AgNW conductive network.\nMoreover, PU/AgNW fibers can be employed as wearable devices to detect\nvarious human motions and to drive light-emitting diodes at a lower\nvoltage (2.7 V).