Strain monitoring mechanisms of sensors based on the addition of graphene nanoplatelets into an epoxy matrix

The study carried out analyses the strain sensor capability of nanocomposites reinforced with different graphene nanoplatelets (GNPs) contents. Nanocomposites with GNPs content around the percolation threshold have shown high gauge factor values, around 65 at high strain. The dominant mechanism of the sensors, based on changes induced in the tunnel and contact resistance, was evaluated. Monitored GNP/epoxy based sensors have shown to be capable of discriminating between tensile and flexural strain modes as the configuration of the GNPs during the tests behaves differently. Flexural strains makes possible the creation of new electrically conductive paths meaning an apparent lower sensitivity while strain produced in a tensile test provokes the breakage of the tunnel or contact based conductive paths. (C) 2015 Elsevier Ltd. All rights reserved.