Smart fabric strain sensor comprising reduced graphene oxide with structure-based negative piezoresistivity

Fabric strain sensors have attracted significantly increased interest as wearable electronics for their flexibility, softness, and wearing comfort in recent years. However, most of the fabric strain sensors fail to pay attention to directionality (negative piezoresistivity) and it remains a big challenge to fabricate wearable fabric strain sensors with a broad sensing range. Here, the strain sensing fabric comprising reduced graphene oxide is developed by using a facile dip-dry-reduce method. Compared to the prior textile strain sensors, the remarkable deformation capacity and a broad reversible strain sensing range (up to 450% strain without breaking) of our treated fabric are with special attention. Meanwhile, it owns great sensitivity (gauge factor of -5.92 under 10.7% strain), stability (> 1000 cycles) and reliability. In addition, sensing strain such as tensile, twist, shear and poke is quantitatively determined. Moreover, the sensing fabric exhibits resistance strain anisotropy (Delta R/R-0 at the wale direction / Delta R/R-0 at the course direction = 5.23), electric thermal behavior (about 60 degrees C under a voltage of 10 V). Finally, the equivalent electrical circuit is provided based on the structure, which is presented for the analysis of electromechanical behaviors, structure-activity relationship, transport models and mechanism. Based on this work, the strain sensing fabric comprising reduced graphene oxide can be knitted to shape for application in human motion detection and electric heater as a kind of flexible smart electronic.