Análise de um sensor baseado em ressonância de superfície de plasma acoplado a um arranjo periódico de nanopartículas metálicas

Abstract

SPR sensors are photonic devices based on surface plasma resonance (SPR), which consists of longitudinal collective oscillation of free electron gas at the interface between a metal and a dielectric. Due to its surface stimuli sensitive response, the use of SPR sensors has been reported for various applications. In this paper, we evaluate an SPR sensor coupled to the periodic array of metal (gold) nanoparticles, which can represent the surface immobilization of metal nanopollutants generated, for example, from the nanocomposites manufacturing process. The the SPR sensor multilayer structure is compounded by a prism, a gold thin film and a SiO2 layer. The sensor response to variations in the nanoparticles array is theoretically analyzed by an analytical model based on the effective permittivity of Maxwell Garnett and the generalized reflection coefficient for planar multilayer structure. The analytical model is validated by comparison with experimental and numerical results, showing great accuracy for a given range of values of the periodic array parameters. The evaluation the allowed wave modes of the sensor structure and the multi-layer structure optimization, for the detection and characterization of static parameters of metal nanoparticles, are the main objectives of the analysis developed in this work.