Evaluation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) using a high figure-of-merit plasmonic multimode refractive index optical sensor

Abstract

In recent years, following the outbreak of the COVID-19 pandemic, there has been a significant increase in cases of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2) and related deaths worldwide. Despite the pandemic nearing its end due to the introduction of mass-produced vaccines against SARS-CoV-2, early detection and diagnosis of the virus remain crucial in preventing disease progression. This article explores the rapid identification of SARS-CoV-2 by implementing a multimode plasmonic refractive index (MMRI) optical sensor, developed based on the split ring resonator (SRR) design. The Finite Difference Time Domain (FDTD) numerical solution method simulates the sensor. The studied sensor demonstrates three resonance modes within the reflection spectrum ranging from 800 nm to 1400 nm. Its material composition and dimensional parameters are optimized to enhance the sensor's performance. The research indicates that all three resonance modes exhibit strong performance with high sensitivity and figures of merit. Notably, the first mode achieves an exceptional sensitivity of 557 nm/RIU, while the third mode exhibits a commendable sensitivity of 453 nm/RIU and a Figure of Merit (FOM) of 45 RIU^-1. These findings suggest that the developed MMRI optical sensor holds significant potential for the early and accurate detection of SARS-CoV-2, contributing to improved disease management and control efforts.

Keywords: Multimode refractive index (MMRI); Optical sensor; SARS-CoV-2; Sensitivity; Split ring resonator (SRR).

Fig. 1

Schematic of the designed sensor (a) 3D and (b) from the top view.

Fig. 2

(a) The reflection spectrum of the proposed sensor without and with back reflector and (b) The reflection spectrum of the proposed sensor without and with cross-arm.

Fig. 3

Structure reflection spectrum for, (a) gold and silver metals for back reflector, (b) gold and silver metals for cross arm, (c) gold and silver metals for SRRs, and (d) dielectric substrate made of SiO₂ and GeO₂.

Fig. 4

Sensor sensitivity in three resonance modes for, (a) gold and silver metals back reflector, (b) gold and silver metals cross arm, (c) gold and silver metals SRRs and (d) dielectric substrate made of SiO₂ and GeO₂.

Fig. 5

FOM of the sensor in three resonance modes, (a) for gold and silver metals back reflector, (b) for gold and silver metals cross arm, (c) for gold and silver metals SRRs, and (d) dielectric substrate made of SiO₂ and GeO₂.

Fig. 6

The sensitivity of the proposed sensor in three resonance modes, (a) versus dimensional parameter changes h_b, (b) versus dimensional parameter changes h_d, (c) versus dimensional parameter changes h_r, and (d) versus dimensional parameter changes g.

Fig. 7

FOM of the sensor in three resonance modes, (a) versus dimensional parameter changes h_b, (b) versus dimensional parameter changes h_d, (c) versus dimensional parameter changes h_r, and (d) versus dimensional parameter changes g.

Fig. 8

Reflectance spectrum of the designed structure in three resonance modes for n = 1.3 and n = 1.4.

Fig. 9

(a) Distribution of electric and magnetic fields from the top view in the first mode, (b) Distribution of electric and magnetic fields from the top view in the second mode, and (c) Distribution of electric and magnetic fields from the top view in the third mode.

Fig. 10

Reflectance spectrum of the structure, (a) for different angles of radiation per n = 1.3 and (b) for different angles of radiation per n = 1.4.

Fig. 11

The impact of losses in both the sublayer and the meta-atoms on the transmittance curve of the sensor, (a) effect of dielectric substrate and (b) effect of a back reflector.

Fig. 12

(a) effective refractive index of the virus against the surface density, (b) the reflection spectrum of the sensor in the third mode as a function of the refractive index of the virus, (c) Resonance wavelength in three resonance modes as a function of the refractive index of the virus and (d) Sensitivity and FOM structure in all three modes for SARS-CoV-2 detection.