Numerical Design of a High-Sensitivity SPR Biosensor for Spike and Nucleoprotein RBD Detection in SARS-CoV-2 Diagnostics

In this study, we present a surface plasmon resonance(SPR) sensor design utilizing a bimetallic prism configuration composed of silver (Ag) and nickel (Ni) for spike and nucleoprotein RBD detection in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The sensor’s performance is enhanced by black phosphorus (BP), a 2-D nanomaterial known for its superior biomolecule adsorption, which improves the interaction between bioanalytes and the sensor surface. Key performance metrics, including sensitivity, detection accuracy (DA), figure of merit (FOM), and full-width at half-maximum (FWHM), are comprehensively evaluated. The sensor’s design is optimized by adjusting the thicknesses of Ag, Ni, and barium titanate (BaTiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub>) layers. The optimal configuration consists of a 40-nm Ag layer, a 9-nm Ni layer, an 11-nm BaTiO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> layer, and a monolayer of BP, achieving the highest sensitivity of 533°/RIU for spike RBD and 525°/RIU for nucleoprotein RBD. The device further demonstrates a DA of 0.325 1/° for the spike RBD and 0.255 1/° for the nucleoprotein RBD, with corresponding FOM of 115 RIU<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> and 108 RIU<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup>, respectively. This setup also demonstrated excellent DA, FWHM, and FOM, making it ideal for real-time, label-free detection applications. The proposed sensor shows great potential, particularly in detecting the SARS-CoV-2 virus, highlighting its suitability for clinical diagnostic use.