Hu Bin, Hu Ning, Li Yuan, Akagi Kentaro, Yuan Weifeng, Watanabe Tomonori, Cai Yong
Department of Mechanical Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan.
Nanoscale Res Lett. 2012 Jul 17;7(1):402. doi: 10.1186/1556-276X-7-402.
In this work, we propose a comprehensive multi-scale three-dimensional (3D) resistor network numerical model to predict the piezoresistivity behavior of a nanocomposite material composed of an insulating polymer matrix and conductive carbon nanotubes (CNTs). This material is expected to be used as highly sensitive resistance-type strain sensors due to its high piezoresistivity defined as the resistance change ratio divided by the mechanical strain. In this multi-scale 3D numerical model, three main working mechanisms, which are well known to induce the piezoresistivity of strain sensors fabricated from nanocomposites, are for the first time considered systematically. They are (a) the change of the internal conductive network formed by the CNTs, (b) the tunneling effect among neighboring CNTs, and (c) the CNTs' piezoresistivity. Comparisons between the present numerical results and our previous experimental ones were also performed to validate the present numerical model. The influence of the CNTs' piezoresistivity on the total piezoresistivity of nanocomposite strain sensors is explored in detail and further compared with that of the other two mechanisms. It is found that the first two working mechanisms (i.e., the change of the internal conductive network and the tunneling effect) play a major role on the piezoresistivity of the nanocomposite strain sensors, whereas the contribution from the CNTs' piezoresistivity is quite small. The present numerical results can provide valuable information for designing highly sensitive resistance-type strain sensors made from various nanocomposites composed of an insulating polymer matrix and conductive nanofillers.
在这项工作中，我们提出了一个全面的多尺度三维（3D）电阻网络数值模型，以预测由绝缘聚合物基体和导电碳纳米管（CNT）组成的纳米复合材料的压阻行为。由于其高的压阻率（定义为电阻变化率除以机械应变），这种材料有望用作高灵敏度电阻型应变传感器。在这个多尺度3D数值模型中，首次系统地考虑了三种主要的作用机制，这些机制是由纳米复合材料制成的应变传感器产生压阻的众所周知的原因。它们是：（a）由碳纳米管形成的内部导电网络的变化；（b）相邻碳纳米管之间的隧穿效应；（c）碳纳米管的压阻。还将当前的数值结果与我们之前的实验结果进行了比较，以验证当前的数值模型。详细探讨了碳纳米管的压阻对纳米复合应变传感器总压阻的影响，并与其他两种机制的影响进行了进一步比较。结果发现，前两种作用机制（即内部导电网络的变化和隧穿效应）对纳米复合应变传感器的压阻起主要作用，而碳纳米管压阻的贡献相当小。当前的数值结果可为设计由绝缘聚合物基体和导电纳米填料组成的各种纳米复合材料制成的高灵敏度电阻型应变传感器提供有价值的信息。
