Optimization of MWCNTs/Epoxy for High Strain Sensor Performance

In this paper, the development of a conductive polymer composite filled with carbon nanotubes (CNTs) for the fabrication of highly performant strain sensors is performed. Films were fabricated via direct mixing method of multi-walled carbon nanotubes (MWCNTs) into epoxy matrix. The optimization of the nanocomposite dispersion is very important step in the preparation of strain sensor and needs deep investigation. By controlling the CNTs concentration and the degree of nanotubes dispersion with the use of suitable process parameters, the sensor performance can be improved. Therefore, these different aspects are considered in this paper. The homogeneity and uniformity of MWCNTs distribution within the polymer were examined by microscopic characterization and atomic force microscopy (AFM). The stability and repeatability of the prepared films were investigated via DC electrical measurement. The percolation threshold was found to be less than 0.3 wt. % of MWCNTs. The piezoresistive resistance response of the composite was highly dependent on the MWCNTs concentration with a gauge factor around 11.09 at 0.3 wt. %. When multiple cycles were applied, a highly stable and repeatable piezoresistive response was achieved.

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