Wavelength-dependent angular shift and figure of merit of silver-based surface plasmon resonance biosensor

Abstract

Herein, we report the dependence of the angular shift (Δθ) and figure of merit (FOM) of the surface plasmon resonance (SPR) biosensor on the excitation wavelength of light (λ) studied using a developed multi-wavelength two prism optical configuration. The experiments have been performed with Bovine Serum Albumin (BSA) and Cytochrome C protein molecules. The λ range was varied from visible to near-infrared. The role of concentration of the biomolecules on the SPR sensitivity has been studied systematically. The experimental results have been compared with theoretical results based on the transfer matrix method. From these results, the value of Δθ is found significantly larger for lower λ values and it is nearly independent of the thickness of the film. However, for a fixed concentration of biomolecules, the FOM of the SPR biosensor is found nearly insensitive to the λ values. Moreover, the role of λ on the characteristic parameters such as depth and FWHM of the resonance has been studied systematically.