SURFACE PLASMON BASED SENSOR WITH MULTILAYER FILMS

Abstract

Surface Plasmon has been used to enhance the surface sensitivity of several spectroscopic measurements such as interference and diffraction and Raman scattering etc. SPR reflectivity measurement can be used to detect molecular adsorptions, such as polymers, DNA or proteins etc. A surface Plasmon resonance (SPR) refractive index sensor for liquids was fabricated and characterized. A thin silver (Ag) films of different thickness (40, 45, 50, 55,and 60nm) was deposited on a prism face and surface Plasmon modes was excited along the interfaces of Ag and air, Ag and water, Ag and sugar solution by prism-coupling using a He-Ne laser. The experimental SPR reflectance curves shifted continuously with increase in sugar concentration. Theoretically SPR dip angles were calculated by WINSPALL — 302 software and found to be approximately same as experimental observation.