Electromechanical properties of a yarn strain sensor with graphene-sheath/polyurethane-core

This paper reports on the fabrication of a new yarn strain sensor based on commonly used polyurethane yarn which is easily incorporated into textile structures by using textile technologies for wearable applications. By integrating graphene/poly(vinyl alcohol) composites as the conductive sheath around yarn, and polyurethane yarn as the elastic core by using a layer-by-layer assembly method that is simple, scalable and low in cost, the merits of both types of materials are incorporated to fabricate sensors with enhanced performance. The combined effects of graphene concentration and number of coatings on sensor properties are elucidated, and on that basis, the electromechanical properties can be modified by adjusting the parameters. The sensors are characterized in terms of sensitivity, resistivity, linearity, repeatability, hysteresis and thermal stability. There are two sensors (graphene concentration of 0.8 wt% and 1.0 wt%, and 12 and 9 cycles of coating respectively) with high sensitivity (gauge factor of 28.48 and 86.86, respectively), good linearity between the change in relative resistance and applied strain (correlation coefficient of 0.95 and 0.97, respectively), good repeatability (repeatability error of 2.03% and 1.81%, respectively), low hysteresis (hysteresis error of 7.03% and 9.08%, respectively) and excellent thermal stability (within the range of 25 °C-310 °C).

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