Optimizing plasmonic nanostructures array for high-performance sensing applications

The localized surface plasmon resonance (LSPR) phenomenon, influenced by the surrounding medium, has been widely employed in optical sensors. Traditional sensors focus on refractive index sensitivity (${\eta }_{RIS}$) but neglect the broad spectral linewidth, thus limiting the detection thresholds of optical sensor. In this study, we present a novel semi-capped gold and silver nanoshells array design to improve sensing performance by optimizing both ${\eta }_{RIS}$ and spectral linewidth. Applying computational modeling framework based on full-wave field analysis, we systematically evaluate electromagnetic field enhancement and LSPR spectral shifts. Furthermore, key metrics, including the figure of merit (FoM) and ${\eta }_{RIS}$, are evaluated to determine the sensing efficacy. Our findings show that semi-capped Au nanoshells array achieve RI-based sensitivity of 536 nm RIU⁻¹ and FoM of 9.2 RIU⁻¹, while Ag-based array demonstrate 559 nm RIU⁻¹ and FoM of 8.1 RIU⁻¹. Moreover, our in-silico study confirms the effectiveness of platform for sensing of streptavidin and offers a detection range beyond 100 nm, surpassing conventional optical sensors. These results offer a novel technique to LSPR-based optical sensors, providing improved sensor efficacy and detection limits.