Rapid Fabrication\nof Graphene Fibers and Fiber-Based\nThermistors for Wearable Devices

Wet spinning of graphene oxide liquid crystals (GO LCs)\nis a scalable\nmethod for creating graphene fibers with applications in flexible\nand wearable devices. In this study, high-shear mixing using a rotational\nCouette flow with a small gap between the stator and rotor was used\nto efficiently produce LC phases from a dispersion of nanometer-thick\nmonolayer GO flakes. One minute of high-shear mixing resulted in LC\nphases with higher viscosity than those produced by conventional magnetic\nstirring. Graphene fibers were obtained by wet spinning and subsequent\nchemical reduction of the GO LCs, achieving improved mechanical and\nelectrical properties. Owing to the efficient production of GO LCs\nand subsequent graphene fibers, the graphene fibers were directly\nused as thermistors for flexible and wearable temperature sensors.\nThe fiber thermistor exhibited a high temperature coefficient of resistance\nof −0.21 ± 0.01 %/°C, high linearity with a correlation\ncoefficient of 0.999, a low time constant of 0.33 ± 0.07 s, and\nhigh repeatability. Therefore, this study demonstrated the potential\nof high-shear mixing for the rapid manufacturing of graphene fibers\nfor wearable devices including smart textiles, soft robotics, and\nflexible healthcare devices.