Optical sensor for nanoparticles

In this paper we investigate a method for the detection of nanoparticles in order to reduce the risk associated with their toxicity, by taking into account the electromagnetic characteristics and the chemical analysis of the surface of a hybrid silicon photonic microresonator. Device sensing capabilities, both optical and chemical, are optimized in order to detect and size the nanoparticle. Thus, a silicon on insulator whispering gallery mode hybrid microresonator having an outer radius of 5 μm and features that are typical of both ring and disk resonators, has been modeled. Quantum electrodynamics principles have been exploited in order to derive the master equation associated with the nanoparticle-resonator interaction. To allow a complete modeling of the sensor attention has been paid to the nanoparticle treatment, with the result that tested nanoparticles need to be chemically stabilized, monodisperse and formed by noble metal nanocolloids, in which a metal core (e.g. Au, Pd, etc) is surrounded by a monolayer or sub-monolayer film of an organic capping agent.