Design of a Dual-Metal Layer SPR Biosensor for Enhanced Melamine Detection Using Black Phosphorus Nanomaterials

Illegal adulteration of milk is toxic to humankind and sometimes leads to adverse health effects. We require rapid screening methods for detecting the presence of melamine in food products, which will enable the user to make appropriate decisions at the right time. In the present work, a biosensor based on surface plasmonic resonance (SPR) for the detection of melamine is introduced. This sensor is designed by incorporating two metal layers followed by a dielectric layer of ZnS and finally adding the top layer with nanomaterials like black phosphorus to increase the sensitivity of the sensor. The sensor is tested with different combinations of the prism at the initial step, and later, the thickness of the metal layer is optimized for all the considered metals. Different SPR structures are considered, and the sensitivity and quality factor (QF) are calculated for each of them before arriving at the best design for the application at hand. The final structure BK7-Ag-ZnSe-Zns-BP-SM was able to achieve a sensitivity of 385.56 \(^\circ /\text{RIU}\) $_{}^{\circ }/\text{RIU}$ and a QF of 98.3 \({\text{RIU}}^{-1}\) ${\text{RIU}}^{-1}$ with a detection accuracy of 1.06. The performance of the sensor is compared with work in the literature, and the proposed sensor is a strong candidate for melamine detection.