Field enhancement and target localization impact on the biosensitivity of nanostructured plasmonic sensors

Abstract : Surface plasmon resonance (SPR) biosensors using field enhancement in nanograting surfaces can overcome sensitivity limitations of conventional SPR biosensors. Nevertheless, the correlation of the local field enhancement established in such structures with sensitivity enhancement has not been extensively studied. We present a numerical study of the coupling effect between the various plasmon modes present in nanograting structures with various structural parameters. We give here a quantitative demonstration of the improvement in sensing performance of SPR biosensors by selective localization of the target molecules in the regions where the electromagnetic field intensity is locally enhanced.