Ti/Au layers impact in prism-based plasmonic sensing of ethanol-fuel purity detection

In this work, the impact of a titanium adhesion layer for the deposition of gold on the performance of an SPR sensor based on the Kretschmann configuration is analyzed. The theoretical and numerical analysis of the SPR from the multilayer structure Fresnel reflection coefficient point of view was taken and experimental results for ethanol purity detection was acquired. It was found that thicker gold layer gives better sensitivities for a constant titanium layer thickness. In fact, an improvement of 27.7% in sensitivity was reached when using a 2 nm titanium and 75 nm gold layers in comparison to a 2 nm titanium and 35 nm gold. However, as a trade-off, a great decrease was detected in the extinction ratio of the system.