This study investigates the enhancement of Surface Plasmon Resonance (SPR) sensor efficiency through the integration of bismuth triborate (BIBO) and lithium triborate (LBO) dielectric layers with two-dimensional materials, including black phosphorene (BP), MXene, graphene, and WSe₂. The sensor design employs the Kretschmann configuration utilizing an Ag-coated FK51A prism, capitalizing on the unique linear optical features of these materials to improve sensitivity and detection accuracy for biomedical applications, especially in the identification of cancerous cells. Simulations were conducted utilizing the transfer matrix method to calculate reflectivity spectra, resonance angle deviations, minimum reflectivity (Rmin), full width at half maximum (FWHM), sensitivity, and quality factor (QF). The findings indicate that BIBO-based sensors surpass LBO-based sensors, attaining enhanced resonance angles, more significant reflectivity dips, and increased sensitivity. BIBO sensors exhibit a maximum sensitivity of 381.42°/RIU and a quality factor of 183.42 RIU⁻¹ at a silver thickness of 54 nm. Among 2D materials, BP-functionalized sensors had the highest sensitivity (426.42°/RIU) and quality factor (102.26 RIU⁻¹), enabling precise discrimination between normal and malignant cells through significant angular resonance shifts. Graphene exhibited a balanced performance with a sensitivity of 364.28°/RIU and a quality factor of 74.34 RIU⁻¹, while MXene and WSe₂-based sensors showed reduced sensitivity and quality factor, indicating limited plasmonic coupling and detection resolution. The appropriate thickness of Ag was shown to be critical, since increased layer thickness enhanced resonance sharpness and sensitivity up to a specific threshold. This study highlights the combined advantages of high-index dielectric layers and two-dimensional materials in improving SPR biosensor capabilities, emphasizing their potential for high-precision, label-free biological diagnostics.
In recent years, graphene metasurface–based biosensors have attracted significant research interest due to their exceptional optical, electrical, and tunable characteristics. The high carrier mobility of graphene, its tunable Fermi level, and its atomically thin 2D structure, when integrated into metasurface designs, give rise to sharp, tunable plasmonic resonances, strong electromagnetic field confinement, and ultra-high refractive-index sensitivity. Graphene metasurface biosensor-enhanced assays for cell morphology and secretion, virus detection, and tissue imaging can improve the accuracy of early disease diagnosis. Microwave and photonics technologies are prime candidates for future sensing and signal processing applications. This review examines current developments in biosensing technologies based on graphene metasurfaces that integrate microwave and photonic technologies, as well as their applications in the biomedical field. Finally, we have highlighted the future development trends of graphene metasurfaces to enhance the sensitivity of biomolecule detection and emphasize their broad range of applications.
This study provides a thorough theoretical investigation into how the donor impurity’s position, geometric deformation, and an external electric field collectively influence the nonlinear optical properties of CdS/ZnSe core/shell prolate quantum dots (CSPQDs) housed within a HfO2 dielectric matrix. We employed the finite element method in COMSOL Multiphysics to solve the Schrödinger equation, utilizing the effective mass approximation (EMA). Our model incorporated the confinement potential, impurity localization, Coulomb interaction, and self-polarization energy. Subsequently, the nonlinear optical rectification (NOR) and second harmonic generation (SHG) coefficients were determined via the compact density matrix (CDM) formalism. Our findings indicate that both impurity displacement and geometric anisotropy disrupt confinement symmetry, thereby boosting NOR and SHG coefficients and inducing a redshift in resonance peaks. Furthermore, applying an external electric field intensifies these effects, presenting an effective strategy for manipulating optical nonlinearity. The key novelty of this is the introduction of a three-dimensional asymmetric CdS/ZnSe CSPQDs system with an off-center impurity, enabling a simultaneously assessment of geometric anisotropy, electric field modulation and dielectric confinement on the nonlinear optical response. These results reveal new mechanisms for tuning nonlinear optical properties through structural and electrostatic modulation, enabling the development of tunable photonic devices, including optical modulators, frequency doublers and nanophotonic sensors.
Effective management of diabetes, a chronic metabolic disorder affecting more than 530 million adults worldwide, relies greatly on precise measurement of glucose levels. In this article, a novel surface plasmon resonance (SPR) biosensor is numerically modeled and optimized for the refractometric detection of glucose in urine. The proposed sensor design, based on the Kretschmann configuration, consists of a multilayered nanostructure comprising indium tin oxide (ITO), silver (Ag), black phosphorus (BP), and antimonene over a BK-7 glass substrate. The optical properties of the proposed sensor are numerically analyzed using the transfer matrix method (TMM) and COMSOL Multiphysics. The structural parameters are then systematically optimized to enhance the overall performance of the designed sensor. The findings show that the proposed sensor configuration exhibits a notable sensitivity of 410.25°/RIU and a linear glucose detection range, with a limit of detection (LOD) of 2.44E-06, confirming strong energy confinement at the sensing interface. Therefore, the proposed sensor is a promising candidate for glucose detection due to its excellent selectivity, stability, and high sensitivity. This work highlights the potential of an analytically modeled SPR sensor and lays the groundwork for future experimental validation and its integration into portable glucose monitor devices.
Surface plasmon resonance (SPR) biosensors are recognized as powerful analytical tools offering real-time, label-free, and highly sensitive detection of biomolecular interactions, making them particularly valuable for medical diagnostics such as malaria screening. SPR arises at the metal-dielectric interface when collective oscillations of free electrons generate confined surface excitations. In this study, we present a Kretschmann-configured SPR sensor optimized for near-infrared (NIR) operation, composed of an SF10 prism, a 70-nm silver film, and a periodic graphene, MoS₂ bilayer (with 7-nm MoS₂ thickness) designed to enhance plasmonic performance and suppress optical interference. The ABCD matrix formalism was employed to compute reflectivity and to monitor refractive index (RI) variations in red blood cells (RBCs). The RI of healthy RBCs was measured as 1.399 ± 0.006 (RIU), while malaria-infected cells exhibited reduced indices of 1.395 ± 0.005 (RIU) (ring stage), 1.383 ± 0.005 (RIU) (trophozoite), and 1.373 ± 0.006 (RIU) (schizont). The optimized structure achieved sensitivities of 198.08 (Deg/RIU) and 201.52 (Deg/RIU) for RI variations of 0.005 and 0.007, respectively. Corresponding reflectivity values were 0.9530 ± 0.006 (a.u.) for healthy cells and 0.9439, 0.8946, and 0.8193 (a.u.) for the infection stages. These results demonstrate the capability of the proposed sensor to discriminate malaria infection stages through precise refractive index analysis, highlighting its strong potential for rapid, label-free, and stage-specific malaria diagnosis.
