Design of a high-performance surface plasmon resonance device for effective measurement of thin liquid film thickness

This study explores the surface plasmon resonance (SPR) and the electromagnetic field responses of multi-layer structures with incident light to enhance the sensitivity and range for measurement of nanoscale thin liquid film thickness. We assess the effect of metal layer type and its corresponding thickness on the optical responses. Notably, the silver (Ag) layer exhibits a more acute reflectance curve with a thickness of 50 nm, which is attributable to the minimization of non-radiative losses and a substantial real component of the dielectric constant of the Ag layer. Furthermore, a correlation between liquid film thickness and reflectance has been established across different metal layer types at specified thicknesses. The Ag layer demonstrates the broadest measurement range for liquid film thickness due to its extensive penetration depth into the dielectric material. Conversely, the sodium (Na) layer presents the narrowest measurement range, albeit with the highest SPR sensitivity.