Refractive Index-Modulated LSPR Sensing in 20–120 nm Gold and Silver Nanoparticles: A Simulation Study

Abstract

Localized surface plasmon resonance (LSPR) based sensing has been a simple and cost-effective way to measure local refractive index changes. LSPR materials exhibit fascinating properties that have significant implications for various bio/chemical sensing applications. In many of these applications, the focus has traditionally been on analyzing the intensity of the reflected or transmitted signals in terms of the refractive index of the surrounding medium. However, limited simulation work is conducted on investigating the refractive index sensitivity of LSPR materials. Within this context, here we simulate the refractive index sensing properties of spherical gold (Au) and silver (Ag) nanoparticles ranging from 20–120 nm diameter within 1.0 to 1.50 refractive index units (RIU). After analyzing the peak optical efficiency and peak wavelength, we report the sensing performance of these materials in terms of sensitivity, linearity and material efficiency, which we refer to as the figure of merit (FOM). Overall, our observations have revealed greatest FOM values for the smallest sized nanoparticles, a FOM of 6.6 for 20 nm AuNPs and 11.9 for 20 nm AgNPs with refractive index of 1.