Effective Deposition of Nano-Sized Silver Particles on Silica to Develop a Sensitive Local Plasmon-Based SPR Sensor

Abstract

Nano-sized silver particles-deposited silicas were prepared by (a) the sol-gel method, the evaporation-condensation of silver on (b) silica glass and (c) sol-gel derived silica film. Optical absorption peak due to surface plasmon resonance (SPR) of silver particles was measured using UV-VIS spectrophotometer. When the films were immersed in liquid, SPR absorption peak of the films (b) and (c) was shifted toward longer wavelength with the increase of the refractive index of the liquid, suggesting that these films can be used as optical sensors. On the other hand, SPR absorption peak of the film (a) was little shifted. The sensitivity to the refractive index change for the film (b) was 81.4 nm, and that of the film (c) made by depositing silver particles on the sol-gel silica was large as 90.2 nm, which may be attributed to less coverage of silver particles with silica matrix than the film (a) and less aggregate of them than the film (b).