Luminescent Sensing via Photonic Nanojets

Abstract

A new optical sensor system based on an array of dielectric aluminum oxide microspheres covered with a layer of chitosan polymer with molecules of a luminescent chemosensitive receptor was developed for determination of ammonia ion concentration in air. The photonic nanojet effect, i.e. strong electromagnetic field local enhancement, was implemented for most effective excitation of the sensitive layer. By using of chitosan swelling polymer the effect of refractive index variation on photonic nanojets excited sensor response was demonstrated. It was shown that under certain conditions such as microsphere diameter and refractive index contrast a detection limit of chemosensitive receptor increases in three times.