Optical Sensor Based on Carbon Nanomaterials for UGLU Detection

This study develops an optical surface plasmon resonance (SPR) biosensing platform for non-invasive glucose detection directly in urine and examines how two-dimensional (2D) nanomaterials modulate sensing performance. Angular interrogation at 633 nm is modeled using a transfer-matrix framework for Au/Si3N4 stacks capped with graphene, semiconducting single-walled carbon nanotubes (s-SWCNTs), graphene oxide (GO), or reduced graphene oxide (rGO). Urine–glucose (UGLU) refractive indices spanning clinically relevant concentrations are used to evaluate resonance angle shifts and line-shape evolution. Sensor metrics—sensitivity, detection accuracy, figure of merit, quality factor, and limit of detection—are computed to compare architectures and identify thickness windows. Across all designs, increasing glucose concentration produces monotonic angle shifts, while the 2D overlayer governs dip depth and full width at half maximum. Graphene- and s-SWCNT-capped stacks yield the lowest limits of detection and the most favorable figures of merit, particularly at higher concentrations where narrowing improves the quality factor. rGO exhibits a thin, low-loss regime that provides large shifts with acceptable broadening, whereas thicker films degrade detectability; GO offers stable line shapes suited to metrological robustness. These results indicate that nanoscale optical engineering of 2D overlayers can meet practical detectability targets in urine without biochemical amplification, supporting compact, label-free platforms for routine glucose monitoring.