Spinning solution viscosity reducing and wet spinning of carbon black-based elastic conductive fibers for sports monitoring and healthcare electrical heating

Elastic conductive fibers are of significant importance in the development of smart wearable strain sensors and electrically heated healthcare fabrics. Nevertheless, considerable quantity of conductive particles has to be incorporated into the fibers for the high conductivity, which would result in a notable increase in the viscosity of the spinning solution. The present study reports a wet spinning carbon black-based composite elastic conductive fiber utilizing copper flake powder to reduce the viscosity of the spinning solution (reduces viscosity by approximately 33%) with enhanced electrical conductivity (up to 56.4 S/m). The fibers can be prepared continuously and in large quantities (laboratory: 10.613 m/min). Moreover, the composite conductive fibers showed excellent durability after bending, cyclic stretching plus unloading (>10,000 cycles) and cyclic washing and drying (>10 cycles) with small changes in electrical properties. When employed as a wearable sensor, the fiber enables the continuous, real-time monitoring of alterations in the kinematic behavior of the body's four major movement joints. Furthermore, the temperature of a healthcare heater by weaving a plain fabric using the conductive fibers as weft can reach up to 38 °C by gradually introducing heat within the safe voltage range for the human body, which prevents the human body from being subjected to low temperatures injury. This demonstrates the potential of this composite elastic conductive fiber in the smart wearable textiles and electrically heated fabrics.