Open Access Nano Express

Multi-scale numerical simulations on piezoresistivity of CNT/polymer nanocomposites

Bin Hu1, Ning Hu2*, Yuan Li3, Kentaro Akagi2, Weifeng Yuan4, Tomonori Watanabe2 and Yong Cai4

Author affiliations

1 Department of Chongqing, University of Science & Technology, Daxuecheng, Chongqing, 401331, People’s Republic of China

2 Department of Mechanical Engineering, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba, 263-8522, Japan

3 Department of Nanomechanics, Tohoku University, 6-6-01 Aramaki-Aza-Aoba, Aoba-ku, Sendai, 980-8579, Japan

4 School of Manufacturing Science and Engineering, Southwest University of Science and Technology, 59 Qinglong Road, Mianyang, 621010, P.R. China

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Citation and License

Nanoscale Research Letters 2012, 7:402  doi:10.1186/1556-276X-7-402

Published: 17 July 2012

Abstract

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.

Keywords:
Carbon nanotube; Conductive network; Nanocomposite; Piezoresistivity; Tunneling effect