Plasmonic SPR sensor using SiO ₂ /Ag-Au alloy/Cu/LaF/Graphene novel Kretschmann structure for SARS-CoV-2 detection: A theoretical study

A surface plasmon resonance (SPR) plasmonic sensor design is numerically investigated using the angle interrogation method for the detection of SARS-CoV-2 using a heterogeneous layered architecture consisting of Silicon dioxide (SiO 2 ) prism/Ag-Au Alloy (AAA)/Copper/Lanthanum fluoride (LaF)/Graphene stack in Kretschmann geometry. The combination of SiO 2 with Ag-Au alloy/Cu bilayer supports surface plasmon excitation with minimal reflectance. Also, LaF interlayer and Graphene nanosheet work together to enhance optical impedance matching and field confinement at the sensing interface, further increasing the performance of the proposed sensor. This proposed study is based on the transfer matrix method to evaluate the reflectivity and relates the shift in the resonance angle to variation in refractive index (RI) caused by an increase in concentration (0–1000[Formula: see text]nM) of SARS-CoV-2 virus surface coverage, thus enabling the inference of virus concentration from the observed angular response. The proposed sensor design attains the highest sensitivity of 386.666 deg/RIU with FoM of 52.98 RIU[Formula: see text].