Deposition of a polymer thin film on a silver surface for surface plasmon sensing

Abstract

Abstract We report a deposition method of a polymer thin film on the silver surface of a surface plasmon sensor for preventing sensitivity degradation in refractive index measurements due to the poor chemical stability of the silver. The deposition of a poly(methyl methacrylate) thin film with a ∼15 nm thickness was conducted by employing a spin coating technique along with a hydrophilicity enhancement of the silver surface using an atmospheric low-temperature plasma treatment. We experimentally verified the thickness by measuring the propagation constant of the surface plasmon. The measured propagation constants that showed the standard deviation at the order of 10−4 indicated microscopical uniformity. Furthermore, the reproducibility of thickness was experimentally verified.