Surface Plasmon resonance sensors for disease diagnosis

Most of the optical sensors based on surface plasmon resonance (SPR) are imitated from two main configurations. Firstly, in the KretschmannRaether configuration, a thin metal layer is sandwiched between the prism and the air. Otherwise, the Otto configuration, there is a gap between the metal and the prism. However, the Kretschmann-Raether geometry is more conventional scheme to generate the surface plasmon wave in sensing technique [1]. The incident light wave is also transverse magnetic wave (TM wave) that can be existed on the metal-air interface and used to excite the SPR under the boundary condition [2]. Most of optical excitation of surface plasmon is based on prism [3], waveguide [4], optical fiber [5] and grating [6]. The SPR wave is described as an electromagnetic wave propagating along the interface between metal and dielectric medium. For three layers system, glass/metallic/analyzed solution, the propagation constant (β) of the surface plasmon wave propagated along the metal-analyze solution interface and the angular frequency, which can be described in the following