Localized Surface Plasmon Resonance on Optical Fiber Surface for Chemical Sensing

This study describes the basic principles of a fiber optic probe that exploits the localized surface plasmon resonance (LSPR) effect achieved by depositing gold nanoparticles (AuNPs) onto the fiber optic transducer. The idea is to read the absorbance spectra of AuNPs and its dependence on the environmental parameter, i.e. the surrounding refractive index, using optical fiber. Basically, we selected a thin optical fiber to encourage the presence of evanescent waves in the surrounding medium; furthermore, the fiber surface has been functionalized allowing the grafting of AuNPs while a silver mirror on the fiber tip allows readout for reflection configuration. The reflected spectra show absorbance characteristics related to single and aggregated AuNPs. In this article, the peaks absorbance, i.e. the depths of the reflected signal, were studied as a function of the surrounding refractive index for application in chemical sensing.