BaTiO3 boosted silver-based SPR sensor for efficient urine-glucose detection in pre-diabetic and early-diabetic stages

The current work studies the impact of BaTiO₃ along with the various monosulfide on the sensing performance of a silver-coated surface plasmonic resonance sensor (SPR) for the noninvasive detection of glucose via urine samples. The considered monosulfides are GeS, ZnS, CdS, and CuS. After the optimization of the BaTiO₃ thickness to 13 nm over the silver based SPR sensor, all above mentioned monosulfides are investigated over the BaTiO₃ (BTO) layer individually. It is shown that GeS shows better performance compared to others. Maximum obtained sensitivity for the optimized structure (Prism (BK7)/ Ag (50 nm)/BaTiO₃ (13 nm)/GeS (01 Layer)/Urine sample) is 527 °/RIU (the highest ever reported to date) for urine sample refractive indices range 1.335, 1.336, 1.337, 1.338, and 1.341 for corresponding glucose concentration of 0 g/dl (non-diabetic), 0.625 g/dl (pre-diabetic), 1.25 g/dl (early diabetic), 2.5 g/dl (diabetic), and 5 g/dl (high-diabetic), respectively. The investigation produced a thorough picture of the distribution of electric fields for distinct monosulfide layers. Other investigated sensing performance parameters such as detection accuracy (DA), quality factor (QF), limit of detection (LOD) are also numerically calculated and are 0.227 deg⁻¹_, 97 RIU⁻¹ and 1.25e-5 respectively. The contrast of the suggested structure to similar relevant published work demonstrates its ability to be used as an efficient label-free biosensor.