Graphene coated nonwoven fabrics as wearable sensors

Wearable electronic devices are becoming increasingly popular. They can bring a tremendous impact to human life. Wearable sensors, a class of wearable electronic devices, have attracted considerable attention because of their importance in healthcare. In this study, graphene-based wearable sensors, which can be directly integrated into clothes or textile products, are fabricated by a simple and cost effective method. Non-woven fabric (NWF) is considered as a green and low cost textile material, and its properties can be engineered for specific functions, such as medical systems, clothing, filter and packaging. A piece of NWF was dipped into graphene oxide (GO) solution and then reduced in HI acid. The GO reduction was confirmed by both X-ray photoelectron spectra and scanning electron microscopy. In the final product, reduced GO sheets were evenly coated on the NWF surface. The as-prepared graphene-NWF (GNWF) sensors exhibited a negative gauge factor at small strain. The signal has good reproducibility in response to stretching, bending and pressure. The highest gauge factor is -7.1 at 1% strain, and the highest sensitivity is 0.057 kPa(-1). The GNWF sensors are able to respond to a series of human motions with the differentiation of various degrees of motions, and it can monitor small scale motions such as pulse and respiration.