Highly\nSensitive, Stretchable, and Wash-Durable Strain\nSensor Based on Ultrathin Conductive Layer@Polyurethane Yarn for Tiny\nMotion Monitoring

Abstract

Strain\nsensors play an important role in the next generation of\nartificially intelligent products. However, it is difficult to achieve\na good balance between the desirable performance and the easy-to-produce\nrequirement of strain sensors. In this work, we proposed a simple,\ncost-efficient, and large-area compliant strategy for fabricating\nhighly sensitive strain sensor by coating a polyurethane (PU) yarn\nwith an ultrathin, elastic, and robust conductive polymer composite\n(CPC) layer consisting of carbon black and natural rubber. This CPC@PU\nyarn strain sensor exhibited high sensitivity with a gauge factor\nof 39 and detection limit of 0.1% strain. The elasticity and robustness\nof the CPC layer endowed the sensor with good reproducibility over\n10 000 cycles and excellent wash- and corrosion-resistance.\nWe confirmed the applicability of our strain sensor in monitoring\ntiny human motions. The results indicated that tiny normal physiological\nactivities (including pronunciation, pulse, expression, swallowing,\ncoughing, etc.) could be monitored using this CPC@PU sensor in real\ntime. In particular, the pronunciation could be well parsed from the\nrecorded delicate speech patterns, and the emotions of laughing and\ncrying could be detected and distinguished using this sensor. Moreover,\nthis CPC@PU strain-sensitive yarn could be woven into textiles to\nproduce functional electronic fabrics. The high sensitivity and washing\ndurability of this CPC@PU yarn strain sensor, together with its low-cost,\nsimplicity, and environmental friendliness in fabrication, open up\nnew opportunities for cost-efficient fabrication of high performance\nstrain sensing devices.