Figure 1From: Graphene oxide-based SPR biosensor chip for immunoassay applicationsSPR biosensor chip using an immunoassay method for detecting a protein using a gold binding. (a) Conventional SPR chip and (b) GOS film-based SPR chip. Intensity of an evanescent field with a depth of approximately 100 ~ 500 nm decays exponentially with increasing distance from the metal. Bimolecular binding, observed within approximately 10 nm of the metal surface, gives rise to a higher signal shift response than that of the interactive process at a distance of 300 nm therefrom. For typical SPR Kretschmann prism coupling that uses a red light to induce the evanescent field, its field intensity is no more than 600 nm in practice.Back to article page