SPR-Based refractive index sensor using BaTiO₃ and WS₂ with Al-Ni bimetal for glucose sensing

In this work, we propose a high-performance surface plasmon resonance (SPR)-based refractive index biosensor to determine the glucose concentration in the urine samples. To achieve the most efficient design for the sensor, four possible designs have been investigated. The proposed design of the sensor uses the Kretschmann configuration, which consists of a BK7 glass prism with Aluminum (Al) and Nickel (Ni) metallic layers separated by a dielectric layer of barium titanate ( BaTiO3 ), and a 2D material tungsten disulfide ( WS2 ) layer placed above the Ni layer. The dielectric layer of BaTiO3 is used to enhance the shift in the resonance angle and WS2 to increase the absorption of the biomolecules, which results in an increase in the sensitivity of the sensor. The performance of the sensor has been numerically investigated using the transfer matrix method at 633nm wavelength. Minimum reflectance at resonance is studied to show the coupling strength of the incident light with the surface plasmons. The thicknesses of the Al and Ni metallic layers have been optimized for maximum sensitivity and minimum reflectance at the resonance. The performance of the proposed sensor has been investigated to obtain sensitivity for different glucose concentrations in the urine samples. The sensor has a sensitivity of 330.5(degrees)/RIU for glucose concentration in the range 0-10g\dl. The corresponding glucose concentration sensitivity is 0.4(degrees)/(g/dl). The proposed study would be helpful in designing the refractive index-based biosensor for medical diagnostics applications.