A highly durable textile-based sensor as a human-worn material interface for long-term multiple mechanical deformation sensing

A sensor with matchable configuration and features is one of the essential components of flexible and wearable electronic systems. The textile is considered as an ideal platform that can integrate diverse flexible electronic devices for developing textile-based wearable electronic systems. A one-dimensional (1D) flexible sensor in a yarn-type configuration is an ideal device for a textile-based wearable system, which can be easily woven and knitted into textile structures for fabricating fabrics via existing textile technologies. However, the development of such a 1D flexible sensor with fiber/yarn-type configuration, multiple deformation sensing function and excellent sensing performance is still a great challenge. Herein a new yarn-type strain sensor with both 1D configuration and excellent weavability was developed by employing the commonly used elastic polyurethane yarn (PUY) as a substrate coated with a reduced graphene oxide (rGO) conductive layer, allowing the sensor to be incorporated within the textile structure easily and efficiently without interfering with the exceptional properties of the fabric as well as the comfort and aesthetic beauty of the clothing. Moreover, as a unique adhesive and skin-friendly material for packaging the sensing structure, mussel-inspired polydopamine (PDA) was introduced into the sensor system, leading to a great enhancement of the interfacial adhesion between the PUY core and conductive sheath, the stability of the sensing layer and the integrality of the sensor. The resultant yarn sensor exhibits excellent sensing properties, with a large gauge factor (131.8 at 90% strain), very low hysteresis, and especially perfect linearity (a correlation coefficient of 0.999). Of great importance is its superior durability even after longtime stretching-releasing for 30 000 cycles. In addition, the sensor demonstrates a good capability to sense the multiple deformations of tensile- and bending-induced strains. Subsequently, a new sensing textile was developed by integrating the yarn sensor into the fabric structure by using the automatic weaving machine, showing a very good and stable sensing performance even after 10 000 testing cycles.