Since carbon nanotubes (CNTs) have attractive electronic and mechanical properties, there have been many efforts to develop CNTs-based electronic devices and sensors. The authors have also validated the possibility of a highly sensitive strain sensor using vertically aligned multi-walled CNTs (MWNTs). However, the strain sensitivity (gauge factor) of our developed strain sensor was fluctuated largely from 0.3 to 100. Therefore, the effect of strain on their electronic properties was analyzed by the combination of molecular dynamics and the first principles calculation. In this study, the effect of radial strain on them was investigated in detail. It was found that the space distribution of state density of CNTs was localized at high-curvature region when a radial strain was applied. In addition, the localization of a state density decreased its state energy and increased the current through the CNT.
