Multilayer Ag/AlPO4/graphene/WS2/MoS2/black phosphorus surface plasmon resonance biosensor for highly sensitive COVID-19 antigen and amino acid detection with machine learning-assisted performance validation

Rapid, sensitive, and reliable biomolecular detection is essential for screening, early disease detection, and point-of-care diagnostics, while conventional analytical techniques often require complex instrumentation and time-consuming procedures. This study proposes a multilayer surface plasmon resonance (SPR) biosensor based on the Kretschmann configuration for COVID-19 viral antigen and amino acid detection. The proposed architecture incorporates silver (Ag), aluminum phosphate (AlPO 4 ), graphene, tungsten disulfide (WS 2 ), molybdenum disulfide (MoS 2 ), and black phosphorus (BP) on a BK7 prism to enhance plasmonic coupling, light–matter interaction, and sensing stability. The proposed biosensor was numerically evaluated using COMSOL Multiphysics to assess its sensing performance for both COVID-19 viral antigens and amino acids. For COVID-19 detection, the optimized sensor achieved an angular sensitivity of 320°/RIU with a corresponding figure of merit (FOM) of 86.486 RIU −1 . In the case of amino acid sensing, the sensor exhibited significantly enhanced performance, reaching a maximum sensitivity of 766.667°/RIU and an FOM of 123.656 RIU −1 . Random Forest Regression achieved R 2 > 0.998, confirming excellent predictive accuracy. These results highlight the proposed biosensor as a promising platform for rapid screening, early disease detection, and real-time biomedical and biochemical sensing applications.