Design of Metal-Insulate-Metal Plasmonic Waveguide Biosensor for Disease Diagnosis

A plasmonic metal-insulator-metal (MIM) biosensor exploits the optical properties of surface plasmon resonances (SPRs) to achieve high sensitivity and specificity in biomolecule detection. The MIM structure in this study features a narrow waveguide as the insulator layer, flanked by elliptical arrays of solid metallic ovals surrounded by thin air layers. These arrays generate localized surface plasmon polaritons, which enhance light-matter interaction. The system operates through dual plasmonic resonances, specifically Fano resonances, resulting in a distinct transmission spectrum. Numerical simulations using the finite element method confirm the sensor's ability to detect minor refractive index shifts, making it highly responsive to small biological variations The simulation results indicate that the proposed design can achieve a sensitivity of tens of picometers for a refractive index change as small as Δn=10−6. This MIM biosensor shows significant potential in applications such as point-of-care diagnostics and environmental monitoring. It can detect a wide range of biomolecules, including proteins, DNA, and pathogens, with high precision, enabling early disease detection and real-time monitoring of environmental contaminants. The enhanced sensitivity provided by Fano resonances positions this technology as a promising tool for personalized medicine, public health, and safety applications