Wearable graphene film strain sensors encapsulated with nylon fabric for human motion monitoring

Abstract Strain sensors have attracted considerable attention in wearable device for human motion detection, medical and healthcare. This paper reports an simple and low-cost fabrication method of wearable strain sensors based on the flexible and high conductivity graphene film which was fabricated by thermal expansion-pressing forming process and encapsulated by nylon fabric. And the fabricated graphene film has superior electrical property which conductivity is upto 90900S/m. The scanning electron microscopy (SEM) pictures indicate that the graphene film was formed by the graphene platelets (GnPs) layers overlapped each other. The strain sensing test shows that the graphene film encapsulated by nylon fabric (GF/NF) strain sensor exhibits a high sensitivity (gauge factor of 9.78 and 47.6 under 0%–12% and 12%–19% strain, respectively), good linearity (correlation coefficient of 0.992 and 0.949 under 0%–12% and 12%–19% strain, respectively) and low hysteresis. Even after more than 1000 cycles of finger joint bending-straightening a stable electrical response is maintained. Moreover, the GF/NF strain sensors could be assembled on various human body joints to detect human behaviors, such as basic human behaviors and the complex behaviors involved in sports activities, demonstrating that they have wide prospects in wearable sensors applications.