Ultra-highly sensitive graphene/polyaniline@epoxidized natural rubber strain sensors for human motion monitoring

Flexible strain sensors are one of the core devices in wearable electronics. At present, it is still difficult to develop flexible strain sensors with high stretchability, sensitivity, and long-term stability. In this work, polyaniline (PANI) was coated on the surface of epoxidized natural rubber (ENR) nanospheres to obtain the PANI@ENR nanospheres, and then mechanically blended with graphene (GN) sheets to prepare the GN/PANI@ENR composites. The composite conductive networks composed of PANI and GN endow the composites with excellent mechanical, electromechanical and strain-sensing performances. The strain-sensing tests show that the ENR composites possess an ultra-high gauge factor (GF) of 29671.7 within 270% of strain. Meanwhile the composites exhibit excellent cycling stability of over 2500 cycles. In addition, the GN/PANI@ENR strain sensors can monitor the large-strain (finger, wrist, elbow and knee joints bending) and small-strain (strains of vocal cord vibration, pulse, facial muscle movements) motions of the human body in real time, indicating a wide range of potential applications in wearable flexible electronics.