Stretchable Polyaniline@Epoxidized Natural Rubber Composites with Strong 3D Conductive Networks for High Performance Strain Sensors

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 study, polyaniline (PANI) is successfully coated onto the surface of epoxidized natural rubber (ENR) nanospheres to form the PANI@ENR composites with core–shell structure by in situ polymerization. At PANI content of 5 wt% (PANI/ENR), the optimally conductive networks of PANI endow the composites with excellent comprehensive properties. The strain-sensing tests show that the PANI@ENR composites possess two successive linear sensing ranges (gauge factor of 7.3 in 0–400% strain, gauge factor of 1.8 in 400–1000% strain) and excellent cycling stability (over 2500 cycles at 0–50% strain). In addition, PANI@ENR-based strain sensors can monitor the movements of human finger joints, elbow joints, and knee joints in real time, indicating a wide range of potential applications in wearable flexible electronics.