A Graphene/Gold-Coated Surface Plasmon Sensor for Sodium Nitrate Detection

A sodium nitrate sensor with graphene/gold coating is presented in this paper. A Kretschmann setup with angle interrogation was used to detect sodium nitrate in the range of 0–15%. Using a graphene coating on top of the 50 nm gold layer showed an improvement in the sensitivity of the sensor. The gold-coated setups had a sensitivity of 0.198°/%. In contrast, the graphene/gold-coated samples showed a sensitivity of 0.244°/% due to the charge transfer between the graphene and the gold and the resulting excited solid electric field. The graphene/gold-coated sensor showed good stability with time in the temperature range of 19–34 °C. This shows that this setup may be beneficial in detecting sodium nitrate