Highly sensitive omnidirectional signal manipulation from a flexible anisotropic strain sensor based on aligned carbon hybrid nanofibers

Although wearable electronic technology has been largely improved to accomplish numerous requirements, the traditional single-axis strain sensor is normally limited in the process of detecting the complex movements of the human body. Here, a simple and efficient strategy is proposed to prepare an anisotropic film that is composed of aligned carbon hybrid nanofibers for multidirectional sensing. The introduction of vanadium nitride (VN) nanoparticles with metallic conductivity improves the conductivity and elasticity of the carbon nanofibers, affording outstanding sensitivity for their sensing behaviors. Due to the ingenious self-alignment, the packed sensor possesses remarkable direction-dependent responsiveness. Specifically, the gauge factor of this anisotropic strain sensor that stretched along the fiber parallel direction is more than 12 times higher than that of the fiber extended in the perpendicular direction. The fabricated sensor also exhibits satisfactory performance with high sensitivity as well as excellent reliability and stability (>4000 cycles). Moreover, an integrated strain sensor has been cross-shaped assembled from these two anisotropic films, displaying a unique capability to distinguish loading direction. As a result, the integrated multidirectional strain sensor achieves the full realization of monitoring human motion with a high degree of freedom, demonstrating its potential application in a new generation of wearable intelligent electronics.