Surface plasmon resonance (SPR) sensors are highly sensitive devices that detect changes in optical properties at the interface between a metal and a dielectric medium. These sensors operate based on the excitation of surface plasmons—collective oscillations of free electrons on a metal surface—when light is incident at a specific angle. SPR sensors are widely used in biochemistry, medicine, and environmental monitoring due to their ability to detect molecular interactions in real time without labeling. This article discusses the principles of SPR sensors, their advantages, and their applications. Experimental measurements were conducted for two binary mixtures: water + glucose (0–0.25 mg/ml) and water + ethanol (0–100%). The results showed a linear dependence of the surface plasmon excitation angle on the concentration of the components, confirming the high sensitivity of SPR sensors to changes in the refractive index of the medium. These findings highlight the potential of SPR sensors for quantitative analysis of substance concentrations in solutions. #CSOC1120