Investigation on Nonlinear Electromechanical Behavior of Conductive Polymer Composites-based Flexible Strain Sensor

Flexible electronics that have significant potential applications on medical care, human motion detection and human-machine interaction have attracted large amount attentions in the emerging electronics field. Particularly, flexible sensors exhibiting perception capability of natural physical signals while sustaining flexible and stretchable properties play a critical role in flexible electronics. In literature, lots of work focus on nanomaterials develop and structure design to promote the applications of variety of flexible electronics. In this paper, a strain sensor based on conductive polymer composites (CPCs) with carbon nanotubes (CNTs) was prepared. Specifically, different weight percentage of CNTs was mixed in the Polydimethylsiloxane (PDMS) substrate. In addition, silicone fluid was introduced into the CPCs to understand the influence on electromechanical performance. Besides, silicone fluid can adjust the flexibility and electrical conductivity of prepared CPCs-based strain sensors. Furthermore, cyclic electromechanical test was deployed to investigate the reliability and dynamical mechanical properties of presented strain sensors. Interestingly, strong nonlinear behavior between electrical resistance and applied strain was presented for strain sensors with different wt% CNTs and whether silicone fluid or not. To understand the mechanism behind this nonlinear behavior, conductive networks competition and time-dependent material mechanical property were discussed to support the presented experimental results. It was believed that the fundamental understanding on the nonlinear behavior of prepared CPCs based strain sensors could pave a way for the wide applications of flexible sensors on variety of areas.