The impact of environmental parameters on the sensing behavior of carbon nanotube–elastomer nanocomposite strain sensors has been investigated, revealing significant effect of temperature and humidity variations on the sensing performance.
Flexible strain sensors based on carbon nanofillers have great potential in the application of skin-adhesive sensors, wearable sensors, and tactile sensors, due to their superior electrical properties. Herein, the electrical properties of highly sensitive PDMS/MWCNT strain sensors made by vacuum filtration method were investigated. In order to obtain the electrical percolation curve of the flexible conductive films, first different samples were made with the same surface area but with different wt. % of CNTs. Then, depending on CNT content, the obtained conductive films exhibited initial electrical resistance in the range of 12.5 KΩ to 22.8 MΩ. The piezoresistive films with the CNT concentration of 1.4 to 2.9 [Formula: see text] had shown superior resistance drop, so this interval was determined as the percolation threshold region. According to the SEM images, the nanocomposite layer thickness of the flexible strain sensors in this region was 790 nm to 1210 nm. Afterward, the percolation curve was obtained using curve fitting to the experimental data and the exact value of the percolation threshold was defined as [Formula: see text]. Finally, in order to determine the minimum gauge factor ([Formula: see text]) of the sensors in percolation region, a flexible strain sensor in the upper limit of this region was selected and the piezoresistive properties of the selected sample were investigated.
In this study, the temperature-dependent piezoresistivity of hybrid carbon black (CB)/carbon nanotube (CNT) nanocomposites is studied using a percolation model with a Monte Carlo simulation approach. With this approach, the temperature-dependency of electrical resistivity and the strain sensitivity of the nanocomposite are investigated. In addition, other parameters such as the aspect ratio, dispersion state and dimensions’ effect on piezoresistivity of the compensated stretchable nanocomposite are investigated. By developing a temperature-dependent percolation model, the temperature sensitivity response of nanocomposite is investigated based on defining the temperature coefficient of resistance of CNT and thermal expansion coefficient of polymer. It is found that the dimensional aspects and dispersion state affected the percolation threshold and resistivity. The obtained results also indicated that the piezoresistivity increased with the decrease in the Poisson’s ratio and intrinsic electrical conductivity. Moreover, the predicted results showed high prediction accuracy for temperature-dependence resistivity compared with the existing experimental data.
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