A simple and cost-effective method for improving the sensitivity of flexible strain sensors based on conductive polymer composites

Abstract Conductive polymer composites (CPCs) based flexible strain sensors requires high performance in terms of sensitivity and stretchability towards potential applications in health monitoring, motion detection and human-machine interaction. In this work, a simple and cost-effective method was proposed to improve the sensitivity yet maintain the stretchability of CPCs based strain sensor. Compared with conventional multi-wall carbon nanotubes/polydimethylsiloxane (MWCNTs/PDMS) flexible strain sensors, silicone fluid was introduced to configure the conductive networks as well as the mechanical properties. It was found that silicone fluid can increase the sensitivity of strain sensor by 10-30 times without reducing the stretchability, which was attributed to the non-covalently functionalized surface of the carbon nanotubes leading to higher ratio of the tunneling resistance to overall resistance of CPCs based flexible strain sensor. Furthermore, the synergetic effect between silicone fluid and CNTs was investigated through conductive network reconfiguration and electromechanical test. The proposed efficient and effective flexible strain sensor preparation approach provides useful insights for high-performance flexible strain sensor design and application.