Plasmonic sensor as a method of measuring concentrations of binary solutions

Abstract

This paper aims to showcase the behavior of Surface Plasmon Resonance (SPR). This optical technique can detect a small change in the refractive index of a sample and shows a shift in the reflective behavior, offering a method to measure precisely the concentration of a binary aqueous solution. The model used for this research is the Transfer Matrix Method (TMM) coded into a mathematical simulation. TMM has contemplated the Kretschmann configuration, composed of an SF10 prism and a gold layer of 50 nm beamed with a 633 nm wavelength laser on p-polarization, for the solution sample used a mix of CuSO₄ and water; by calculating the refractive index as a function of the binary solution concentration is possible to associate the reflective response to the concentration of the solution. The simulation presents a shift to the right into the angular response and, therefore, to the SPR angle to the increased concentration of the solution; this relationship is also shown in the SPR angle and the concentration of the solution in the calibration curve. These results may indicate the potential application of the technique as a sensor capable of measuring concentration in binary aqueous solutions, specifically, as a monitoring technology for water contaminants detection.