Novel polymer waveguide-based surface plasmon resonance (SPR) sensor

A novel polymer waveguide for surface plasmon resonance (SPR) sensing is theoretically proposed and experimentally demonstrated. The waveguide sensor simply consists of a polymer and a thin gold film on a silica layer. According to the multilayer transfer-matrix theory and the multiple reflection theory, a formula describing the reflectivity of total light power is deduced and analyzed, which is related to the dielectric constant of both the waveguide and the metal, the thickness of the metal film, and the length of the sensing area. By the addition of liquids with refractive indices ranging from 1.40 to 1.47 in the sensing area, the proposed polymer waveguide-based surface plasmon resonance sensor exhibited an experimental sensitivity of 1489 dB/RIU. With a refractive index range between 1.45 and 1.47 beyond the measurement range of typical SPR fiber based sensors, the reported device operates with very high sensitivity. The proposed portable, compact, and simple polymer waveguide-based surface plasmon resonance sensor shows potential for low cost and on-chip multiple channel sensing for practical applications.