Plasmonic biosensor

Issues on optical and physical characteristics of plasmonic biosensor were described. Starting from physical principles of surface plasmons, resonant coupling, and dispersion, we then discussed more practical and essentially important aspects on dielectric functions, penetration depth, and functional differences in SPR imaging systems. Scaling procedure from experimentally obtained SPR curve to incident angle was also discussed. Also, physical background of plasmon-resonant, extinction-, scattering- and near-field cross-section of metallic nanoparticles was briefly explained, based on Mie scattering. Extinction spectra were calculated for various sizes of gold and silver nanoparticles and compared with experimentally observed extinction spectra for colloidal gold.