An investigation on hybrid AlN-graphene surface plasmon resonance sensor for refractive index-based pathogen...

The effective detection and monitoring of various pathogens remain critical for controlling outbreaks and ensuring timely medical intervention. To address this issue, the current work proposes a surface plasmon resonance (SPR) sensor based on Kretchman configuration for precise detection of change in refractive index of pathogens related to dengue diseases by studying the different blood components like plasma, platelet, and hemoglobin. The sensor is envisaged by stacking layers of ${\text{TiO}}_2$ , Ag, AlN, graphene, and sensing medium on a BK7 prism substrate. The structure is designed and modeled in COMSOL Multiphysics to clearly demonstrate the excitation of plasmonic wave close to the metal surface. The thicknesses of all the constituent layers have been meticulously optimized by studying the change in characteristics of the angular reflectance. Notably, the penetration of evanescent field into the sensing medium enhances the light-analyte interaction, which leads to high sensitivity. Moreover, a detailed electric field analysis is carried out at the interface of each layer. The simulation upshots revealed that the proposed sensor can detect infected plasma, platelet, and hemoglobin with a sensitivity of 138.46 deg./RIU, 163.63 deg./RIU, and 182.85 deg./RIU, respectively. This approach offers significant advantages, including rapid detection of pathogens, high sensitivity, and the ability to integrate with portable diagnostic devices, making it a promising tool in the biomedical industry.