In-situ growing of helical carbon fibers on graphene for high-performance flexible strain sensor

Flexible strain sensors have broad applications in the field of human health monitoring. It is essential to design and manufacture sensors with high sensitivity and stability. The aim could be achieved by constructing multi-level interface structure with non ohmic contact in the flexible three-dimensional conductive network. In this paper, helical carbon fibers (HCF) were grown in situ on the surface of 2D sheet material graphene. The prepared composite conductive material GO/HCF has an excellent 3D structure, significantly enhancing the sensor's sensitivity. PDMS and NH4HCO3 encapsulated strain sensor (GO/HCF/N) has GF values of up to 622.8. Besides, the sensor exhibits unique sensing characteristics that other sensors do not have: under low strain conditions, the resistance of the sensor increases with the increase of deformation, and when the deformation exceeds a certain value, the resistance decreases instead. Therefore, GO/HCF/N sensor has a shallow detection limit (0.1 %) and works steadily after 1000 times tensile release cycles. This flexible strain sensor can quickly and accurately identify different human movements in human health monitoring.