Localized surface plasmon resonance based nanocube-nanosphere dimer biosensor

Abstract

For this paper, the Localized Surface Plasmon Resonance (LSPR) properties of bimetallic nanoparticles in the shape of a nanocube-nanosphere and consisting of Drude metals was analysed. The refractive index based plasmonic bio-sensing with nanocube-nanosphere dimers was studied through the illumination of a broadband beam at normal. The power absorption curves and electric field graphs for different material combinations between the nanocube and nanosphere were analysed to select the best material combination, which was found as silver nanocube-silver nanosphere. Using that combination, the gap between the nanocube and nanosphere was varied to find out the optimal gap, which was found as 1 nm. Taking that gap and material combination, the physical dimensions of the nanocube and nanosphere were varied and the best nanocube-nanosphere size was selected which was a nanocube of side length 20 nm and a nanosphere of radius 12.5 nm. The refractive index sensitivity was analysed in terms of different dielectric media. The sensitivity of the nanocube-nanosphere was also calculated in the presence of Lysozyme (Lys), Human Serum Albumin (HSA), Human gamma-immunoglobulin (IgG) and Human Fibrinogen (Fb) protein samples. Therefore, a comparative analysis was done to highlight how well the dimer performed as a biosensor in certain conditions. All of these processes were simulated using the software FDTD solutions by Lumerical.