Modal Analysis of Surface Plasmon Resonance Sensor Coupled to Periodic Array of Core-Shell Metallic Nanoparticles

Abstract

The influence of a dielectric shell on metallic spherical nanoparticles [core-shell nanoparticles (CSNps)] in the resonant modal response of a surface plasmon resonance (SPR)-type sensor is presented. The planar multilayer sensor structure, based on the Kretschmann and surface plasmon coupled emission (SPCE) configurations, is coupled to a periodic array of these nanoparticles. In the first configuration, the CSNps are considered as a homogeneous layer with effective permittivity given by the Clausius-Mossotti mixing formula and polarizability of a core shell for a quasi-static scattering regime. In the second configuration, it performed an evaluation via the discrete complex image method (DCIM). Electromagnetic wave propagation is evaluated by the generalized reflection coefficient for multilayer structures. The analytical results are validated by numerical simulations performed via finite element method and also by experimental data. We observed that the dielectric shell thickness affects considerably the sensibility of the sensor when analyzing the change in other parameters of the CSNps array.Resonance 186

Análise de Arranjo Periódico de Nanodipolos Sobre Plano de Ouro Através da Função de Green 3D

“…2a). Neste trabalho ambos os meios são considerados não magnéticos, sendo o meio 1 (ε 1 , µ 1 ), z > d, o espaço livre , e o meio 2 (ε 2 , µ 2 ) , z < d, caracterizado pela permissividade relativa complexa do ouro que, no espectroóptico,é descrita pelo modelo de Lorentz-Drude com excelente precisão [11]. Para determinar analiticamente os campos elétrico e magnético, primeiramente foi definido o potencial magnético em ambos os meios através da solução da equação diferencial vetorial de Helmholtz, não homogênea no meio 1, e homogênea no meio 2 [14]:…”

“…Note, na Fig. 5, o surgimento de ondas plasmônicas de superfície sobre a camada metálica, justamente devidoà predominância do modo TM queé exigência necessária ao surgimento destas ondas [11,17].…”

“…Especial atenção tem sido dada a nanopartículas posicionadas sobre metais nobres (ouro e prata) [9,10], pois, quando excitadas, sua re-irradiação pode provocar ondas A. F S. Cruz, K. Q. Costa, N. W. P. Souza, Programa de Pós-Graduação em Engenharia Elétrica (PPGEE), Universidade Federal do Pará (UFPA), Belém-PA, Brasil, E-mails: felipe.andcruz@gmail.com, karlo@ufpa.br e nadsonwelk-son@unifesspa.edu.br plasmônicas de superfície na interface metálica [11] que, por sua vez, alteram características de concentração e emissão de luz do conjunto [5]. Diante disto, diferentes arranjos periódicos de nanoantenas têm sido propostos [12,13].…”

Electromagnetic model of a nanodipole array above a double‐layer graphene by periodic green's function

“…A conventional SPR sensor based on the surface plasmon coupled emission (SPCE) configuration consists of a multilayer structure (prism/metal/dielectric) coupled to a microfluidic channel where immobilised active particles are excited by an external electromagnetic source [12–14]. Due to the nanometric size of these particles, the radiation‐matter coupling is typically dominated by radiation in the dipolar mode [15], thus, these active particles re‐radiate waves that are coupled at the metal/dielectric interface, exciting surface plasmon polaritons (SPPs) waves, which in turn couple the dipolar radiation through the metallic material in the form of highly polarised directive TM waves in the region of the dielectric prism [16].…”

“…The sensing process is based on the electromagnetic response of the device in the form of a cone of light, whose characteristics are functions of the refractive properties of the sample in the microfluidic channel. The electromagnetic response of this device can be studied from an array of nanodipoles on the multilayer structure, where the active particles are modelled as Hertzian dipoles [12, 14, 17].…”