Graphene-based fiber sensors with high stretchability and sensitivity by direct ink extrusion

Free-standing stretchable fibers with highly flexibility and sensitivity are the key components of the smart wearable electronic devices. In this work, one-dimensional graphene-based fibers with aligned morphology are fabricated by direct ink extrusion, in which graphene and poly(dimethyl siloxane) (PDMS) can be integrated into a conductive network. The graphene-based fibers can respond to multiple deformations such as bending, twisting, compressing, and stretching. The various response amplitude with a reversible electrical resistance change can be obtained from multiple strain cycles, which exhibits high sensitivity and broad range in strain sensing. The ultra-sensitive electromechanical property with a gauge factor of 65 under 6% strain is attributed to the interwoven graphene network and could be cycled 600 times of continuous stretching-releasing process with less than 6.2% attenuation in the response signal. The intrinsic dynamic fracture procedure and mechanism of graphene-based fibers are investigated as a result of the gradual growth of locally generated cracks. The controllable fabrication of graphene-based fibers with high sensitivity shows great potential applications in stretchable wearable sensors for real-time monitoring and distinguishing of human motion and gestures.