Highly Sensitive Bimetallic-Metal Nitride SPR Biosensor for Urine Glucose Detection

The present study introduces a highly sensitive bimetallic SPR biosensor based on metal nitride for efficient urine glucose detection. Using a BK-7 prism, Au (25 nm), Ag (25nm), AlN (15 nm), and a biosample (urine) layer, the proposed sensor comprises of five layers. The selection of the sequence and dimensions of both metal layers is based on their performance in a number of case studies including both monometallic and bimetallic layers. After optimizing the bimetallic layer as Au (25 nm) - Ag (25 nm), various nitride layers were used to further increase the sensitivity by utilizing the synergistic effect of the bimetallic and metal nitride layers through case studies of several urine samples, ranging from nondiabetic to severely diabetic patients. AlN is determined to be the best suited material, and its thickness is optimized to 15 nanometers. The performance of the structure has been evaluated using a visible wavelength, i.e., $\lambda = 633$ nm, in order to increase sensitivity while providing room for low-cost prototyping. With the layer parameters optimized, a significant sensitivity of 411 degrees/RIU (Refractive Index Unit) and figure of merit (FoM) of 105.38 /RIU has been achieved. The computed resolution of the proposed sensor is 4.17e-06. This study's findings have also been compared to some recently reported results. The proposed structure would be useful for detecting glucose concentrations, with a rapid response as measured by a substantial shift in resonance angle in SPR curves.