A high-sensitivity refractive index biosensor based on Si nanorings coupled to plasmonic nanohole arrays for glucose detection in water solution

Abstract

In this paper, a refractive index biosensor is proposed which employs Si photonic nanorings coupled to ring-shaped plasmonic nanohole arrays (PNA) on a hybrid substrate to facilitate sensing of different glucose concentrations in water solution. The proposed structure can be used as a single-mode refractive index biosensor with a high sensitivity of 1278 nm/RIU, a figure of merit (FoM) of 168.1 RIU−1, and good detection accuracy of 0.13 nm−1. The sensitivity and FoM values of the proposed structure are highest in comparison with many reported structures in recent years, while it uses a simple structural topology. The effects of various structural parameters on the reflection spectrum and sensing performance are comprehensively surveyed using the 3D FDTD method. Using the proposed structure, the strength of the interaction between the applied light and the analyte is effectively enhanced and the propagation loss is relatively reduced. Hence, the designed structure is an appropriate candidate for ultrasensitive biosensing applications.