Geometry and near-field coupling effects on the refractive-index sensitivities of individual Ag nanoparticle sensors

The refractive-index sensitivities of sensors of individual Ag nanoparticles (including nanodisks, nanocubes, and nanoprisms) and nanoparticle clusters are investigated numerically and analytically. It is demonstrated that the refractive-index sensitivities are a nonlinear function of the peak positions of localized surface plasmon resonances (LSPRs) with fixed surrounding mediums and metal materials at optical wavelengths. Moreover, this nonlinear function is independent of Ag nanoparticle geometries and near-field couplings between components within nanoparticle clusters. In addition, the discrepancies between our results and those of literatures are also discussed. The present work facilitates choosing appropriate peak positions of LSPRs for plasmonic sensing and detections by only analytically calculating with an equation under LSPR condition.