A completely novel Surface Plasmon Resonance (SPR) biosensor based on 2 D material Graphene and Transition Metal Dichalcogenides (TMDC) WS2 (Tungsten disulfide) is proposed for the detection of the urine glucose concentration levels. This proposed structure is comprised of the five-layered in the order of the Prism- Au-Graphene-WS2-Biosample.
Bio sample is having the glucose level in the range of 0 -15 mg/dl (for normal person) and 0.625 gm/dL, 1.25 gm/dL, 2.5 gm/dL, 5 gm/dL, and 10 gm/dL (for diabetic person) respectively with the corresponding refractive indices of 1.335,1.336,1.337,1.338,1.341,1.347.
The performance parameters ie. reflectance SPR curves and sensitivity are obtained for the optimized thickness of Gold (Au), Graphene, and WS2 layers, by using the transfer matrix method. Compared with the conventional SPR based biosensor, graphene-WS2 layers can increase the sensitivity of the biosensor. The highest sensitivity of the SPR biosensor with an optimized thickness of 50 -nm Au/0.34-nm Graphene/1.60-nm WS2 is 211 °/RIU which is approximately 40% and 15% higher than the sensitivity of the conventional biosensor and the graphene-based biosensor respectively. Due to its unique optical properties, WS2 remarkably enhances the sensitivity of the proposed sensor in the detection of glucose concentration. Additionally, it is expected that the proposed biosensor has the potential to be fabricated in the scale of nonorange and can be used where the continuous monitoring of glucose is required because of its significant response corresponding to the minute change of 0.001 in the refractive index of the biosample.
Multimode waveguides on lithium niobate-on-insulator (LNOI) and silicon-on-insulator (SOI) platforms are numerically investigated in buried, rib, and strip configurations. Performance of waveguides is compared in terms of waveguide cross-sectional area, dispersion, mode hybridization, and power confinement for both quasi-transverse electric and quasi-transverse magnetic modes. Tall waveguides with single mode in the horizontal direction, supporting higher order modes in the vertical direction, are analyzed. Also, wide waveguides with single mode in the vertical direction, supporting higher order modes in the horizontal direction, are studied. Designs that overcome mode hybridization are proposed, which are well suited for applications such as optical interconnects. LNOI waveguides were found to exhibit lower dispersion in all the configurations, with power confinement and physical dimensions comparable to those of SOI waveguides. The results are instrumental in design optimization of multimode components for on-chip mode-division multiplexing schemes and multiparameter sensing applications. Electro-optic effect is also illustrated in a buried multimode LNOI waveguide that is largely useful in modulation and switching applications.
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