Development and characterization of graphene nanoplatelet-based strain sensors for structural health monitoring

Nanocomposites based on graphene nanoplatelets (GNPs) were developed using SX10 EVO epoxy resin matrix. Electrical conductivity measurements showed significant improvement with increasing GNP content, reaching a maximum value at the saturation of the electrical network. The electrical behavior and performance of the fabricated nanocomposite sheets as strain sensors were investigated. Sensors with graphene content near the percolation threshold exhibited the highest gauge factor due to the tunneling effect, making them more sensitive to strain. However, further increasing the GNP content enhanced electrical conductivity while reducing sensitivity. The sensors demonstrated good stability and reversibility. The highest gauge factor (GF) was observed in $5 \mathrm{wt} \%$ GNP content, with a value near 20. Finally, the response of the sensors under cyclic tests was assessed, demonstrating the high robustness of the proposed sensors for aerospace applications.