Sensitivity improvement of MWCNTs/epoxy composite strain sensor

We investigated the optimal manufacturing conditions for a multi-walled carbon nanotubes (MWCNTs)/epoxy composite strain sensor in order to improve the sensitivity of the sensor. The specimens were manufactured and the electrical properties of the specimens were compared according to different MWCNT concentrations and dispersion methods. The sensitivity of MWCNTs/epoxy composite strain sensor was investigated quantitatively by measuring resistance changes according to the variation of a constant strain. Scanning electron microscopy (SEM) images confirmed that MWCNTs/epoxy composites with different CNT concentrations have a good homogeneity and dispersion. In addition, we attempted to evaluate the sensing characteristics and compared them with those of a conventional foil strain gauge. A MWCNTs/epoxy composite was attached to an acrylic beam. The response of the MWCNTs/epoxy sensor was fairly good, and the result was nearly identical to that of the strain gauge. In order to verify the performance of the sensor, a Wheatstone bridge circuit and a signal conditioning circuit were used. This current study on the sensitivity of MWCNTs/epoxy composite sensors provides a useful tool for designing smart sensing and multifunctional polymer composites. The concept of using these conductive fillers provides a low-cost and effective way to fabricate piezoresistive polymer nanocomposites for structural health monitoring applications.