Enhanced urine glucose sensing using two-dimensional TMDCs-based SPR biosensor

Surface plasmon resonance (SPR) sensing technology has been extensively applied in biomedical applications, but traditional SPR sensors often suffer from limited sensitivity. In this study, a bi-metallic/ Two-Dimensional (2D) Transition-Metal-Dichalcogenides (TMDCs)-based SPR biosensor has been proposed to achieve improved performance in urine glucose detection utilizing the Lumerical Finite-Difference-Time-Domain (FDTD) platform. The design incorporates different TMDCs materials, including WS₂, WSe₂, MoS₂, MoSe₂, and MoTe₂ to enhance the sensor's sensitivity, whereas the MoS₂-based structure demonstrates the superior sensitivity. The optimized CaF₂-Ag-Al-MoS₂ structure has successfully detected the urine glucose concentrations ranging from 0 to 0.015 g/dL in non-diabetic individuals and from 0.625 to 10 g/dL in diabetic persons, corresponding to a refractive index (RI) range from 1.335 to 1.347, achieving outstanding sensitivity of 455.83 deg/RIU with detection accuracy of 1.32 and a quality factor of 110.10RIU^-1. The sensor exhibits a broad linear response to urine glucose, indicating accurate and reliable detection. Additionally, the electric field analysis confirms that the integration of TMDCs significantly enhances sensitivity and ensures effective bimolecular interaction with a penetration depth of 190 nm. These enhancements are attributed to the superior optical absorption and large surface-to-volume ratio of TMDCs. In particular, MoS₂ stands out with the highest refractive index, which strengthens the confinement of the evanescent field and increases its interaction with biomolecules, thereby boosting sensitivity. Hence, the developed SPR biosensor shows promise as a cost-effective, label-free refractive index sensor for non-invasive tracking of glucose levels in the human body.