Investigation into tensile hysteresis of polyurethane-containing textile substrates for coated strain sensors

Flexible sensors based on the highly elastic Polyurethane (PU)-containing textile substrates have been frequently incorporated in enormous wearable applications. However, the desirable sensing properties such as stable sensitivity, small hysteresis and good repeatability depend on the mechanical resilience of the textile substrates. This paper conducts a systematic investigation into the mechanical hysteresis of the PU-containing textile substrates, from fibers to yarns and then fabrics. The impact of fiber materials, yarn structures, and fabric constructions on the overall tensile properties of the PU-containing substrates were examined. It was found that fibers of high elasticity, stable yarn structure with excellent recovery, as well as appropriate fabric construction are effective to reduce the mechanical hysteresis of the textile substrates. Coated strain sensors based on different substrates were then fabricated. Results show that smaller mechanical hysteresis of the PU-containing substrates generally led to lower electromechanical hysteresis and better repeatability of sensors. This paper gives all-round consideration of the fibers and structure features of substrates to provide recommendation for reducing mechanical and electromechanical hysteresis of sensors based on PU-containing textiles and benefiting the design and optimization of other flexible sensors.