High-performance strain sensors based on functionalized graphene nanoplates for damage monitoring

A high-performance piezoresistive strain sensor can be used to monitor the deformation and damage in the structural composites. We developed the sensors with high sensitivity by structuring a 3D graphene network into an epoxy matrix. One-pot synthesis of amino-functionalized graphene nanoplates (f-GnP) was realized from graphite oxide and polyether amine, so that the dispersion of graphene in epoxy was well improved. The f-GnP/epoxy composite with lower percolation threshold, i.e. ~1.31 vol%, exhibited relatively high gauge factor of ~45 and Young's modulus of ~2.2 GPa. Importantly, the studied sensor with f-GnP network structure could help to detect the initiation and accumulation of damage in the structure materials under tensile loading. The normalized electrical resistance change (δR/R_o) of the composite sensor initially almost increased linearly, then shown nonlinear drift and irregular ladder-shaped growth with the appearance of irreversible damage and deformation. These results suggest that the graphene/epoxy piezoresistive sensors show promising applications for the damage monitoring of structural materials in the field of aerospace.