Ultra-flexible graphene/nylon/PDMS coaxial fiber-shaped multifunctional sensor

The development of flexible and wearable devices is mainly required for tactile sensing; as such devices can adapt to complicated nonuniform surfaces, they can be applied to the human body. Nevertheless, it remains necessary to simultaneously achieve small-scale, portable, and stable developments in such devices. Thus, this work aims at fabricating a novel, lightweight, ultra-flexible, and fiber-shaped coaxial structure with a diameter of 0.51 mm using polydimethylsiloxane/graphene/nylon material, based on piezoresistive and triboelectric principles. The piezoresistive-based robotic-hand-controlled sensor thus realized exhibits a response time of 120 ms and a fast recovery time of 55 ms. Further, the piezoresistive-based sensors effectively feature whisker/joystick-guided behaviors and also sense the human finger contact. Owing to the triboelectric-based self-powered nanogenerator behavior, the resulting sensor can convert mechanical motion into electrical energy, without adversely affecting human organs. Moreover, this triboelectric-based human finger sensor can be operated under different bending modes at specific angles. Notably, this multifunctional sensor is cost-effective and suitable for various applications, including robotic-hand-controlled operations in medical surgery, whisker/joystick motions in lightweight drone technology, and navigation with high-sensitivity components.