Refractive Index Sensing Using Nano-Plasmonic Structures

Abstract

Metallic nanostructures exhibit optical resonance, where free electrons oscillate at the surface, creating strong near field. This resonance wavelength is sensitive to the surrounding refractive index, and therefore a subtle change of the surrounding environment can be monitored by tracking the resonance. This sensing scheme can be applied to detect biological targets by properly functionalizing the surface. In this article we describe how such nano-biosensors work as well as application examples using plasmonic nanostructures. Since the optical fi eld distribution at the metal surface determines the sensor performance, we also show how nanoscopic optical fi eld can be experimentally visualized by electron microscopy based methods.