Chikungunya virus has been discovered in about 60 countries of the world. It leads to joint pain, joint swelling, headache, muscle pain, and fatigue of the human body. In this work, a surface plasmon resonance (SPR)based sensor is developed to detect chikungunya virus through normal and infected platelets and plasma blood cells. The proposed SPR-based sensor uses silicon and graphene layers coated over the base of a glass prism sputtered with a silver layer. The graphene layer has the advantage of enhancing the biomolecules adsorption on the metal layer. The silicon layer between silver and graphene enhances the sensor performance. The number of graphene layers along with the thicknesses of silicon and silver layers is optimized to get the highest sensitivity of the detector. To investigate the effect of the light source wavelength, simulations are performed for four different wavelengths. The highest sensitivities exhibited by the SPR-based sensor are 393 and 160 deg/RIU for the platelets and plasma cells, respectively.
相似文献Metal-dielectric-graphene hybrid heterostructures based on oxides Al2O3, HfO2, and ZrO2 as well as on complementary metal–oxide–semiconductor compatible dielectric Si3N4 covering plasmonic metals Cu and Ag have been fabricated and studied. We show that the characteristics of these heterostructures are important for surface plasmon resonance biosensing (such as minimum reflectivity, sharp phase changes, resonance full width at half minimum and resonance sensitivity to refractive index unit (RIU) changes) can be significantly improved by adding dielectric/graphene layers. We demonstrate maximum plasmon resonance spectral sensitivity of more than 30,000 nm/RIU for Cu/Al2O3 (ZrO2, Si3N4), Ag/Si3N4 bilayers and Cu/dielectric/graphene three-layers for near-infrared wavelengths. The sensitivities of the fabricated heterostructures were?~?5–8 times higher than those of bare Cu or Ag thin films. We also found that the width of the plasmon resonance reflectivity curves can be reduced by adding dielectric/graphene layers. An unexpected blueshift of the plasmon resonance spectral position was observed after covering noble metals with high-index dielectric/graphene heterostructures. We suggest that the observed blueshift and a large enhancement of surface plasmon resonance sensitivity in metal-dielectric-graphene hybrid heterostructures are produced by stationary surface dipoles which generate a strong electric field concentrated at the very thin top dielectric/graphene layer.
相似文献The organic non-crystalline medium of 5,6-dichloro-2-[[5,6-dichloro-1-ethyl-3-(4-sulfobutyl)-benzimidazol-2-ylidene]-propenyl]-1-ethyl-3-(4-sulfobutyl)-benzimidazolium hydroxide (TDBC) is emerging as possible alternative plasmonic material for noble metal in visible region. In this paper, a novel long-range surface exciton-polariton (LRSEP) sensor based on TDBC film covered with graphene is reported. To enhance the imaging sensitivity, the thickness of TDBC film and the number of graphene layers are optimized. The result shows that the optimized imaging sensitivity is enhanced to 3243 RIU−1 when ns = 1.34. Compared with the traditional noble metal film-based sensor, the proposed LRSEP sensor demonstrates that the imaging sensitivity has been greatly improved. This is the first study of the TDBC film-based LRSEP sensor, which we hope to support the potential development of chemical sensing and bio-sensing.
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In this paper, a graphene strip is introduced into a metal-insulator-metal (MIM)-integrated square cavity hybrid structure; the transmission spectra are theoretically investigated by the finite different time domain (FDTD) methods. An asymmetric Fano resonance dip that has high figure of merit (FOM) value appears in the transmission band. According to the multimode interference coupled mode theory (MICMT) analytical method, the Fano resonance originates from the coherent coupling between TM10 cavity magnetic mode and graphene plasmonic resonance electric mode. The center wavelength, full width at half maximum (FWHM), and FOM value of the Fano resonance can be tuned dynamically by altering the Fermi level of the graphene. Through breaking the symmetry of the hybrid structure or introducing double graphene strips with different Fermi level into hybrid structure, double Fano resonance are realized. This study can provide some theoretical basis and design reference for designing ultrahigh sensitivity plasmonic sensor.
相似文献We propose an ultrasensitive and tunable mid-infrared sensor based on plasmon-induced transparency (PIT) in a monolayer black phosphorus metasurface. Results show that there are two PIT windows, each of which occurs when the long axis of the metasurface is placed along the MBP’s armchair and zigzag crystal directions, respectively. The corresponding sensors based on these PIT effects show high sensitivities of 7.62 THz/RIU and 7.36 THz/RIU. Both PIT frequencies can be tuned statically by varying the geometric parameters or dynamically by changing the electron doping of monolayer black phosphorus, making the sensors adaptable to tackle with a variety of scenarios. We expect that this work will advance the engineering of metasurfaces based on monolayer black phosphorus and promote their sensing applications.
相似文献A highly sensitive dual-core photonic crystal fiber based on a surface plasmon resonance (PCF-SPR) biosensor with a silver-graphene layer is described. The silver layer with a graphene coating not only prevents oxidation of the silver layer but also can improve the silver sensing performance due to the large surface-to-volume ratio of graphene. The dual-core PCF-SPR biosensor is numerically analyzed by the finite-element method (FEM). An average spectral sensitivity of 4350 nm/refractive index unit (RIU) in the sensing range between 1.39 and 1.42 and maximum spectral sensitivity of 10,000 nm/RIU in the sensing range between 1.43 and 1.46 are obtained, corresponding to a high resolution of 1 × 10−6 RIU as a biosensor. Our analysis shows that the optical spectra of the PCF-SPR biosensor can be optimized by varying the structural parameters of the structure, suggesting promising applications in biological and biochemical detection.
相似文献The steering of guided light in surface plasmon resonance (SPR) sensing platforms introduced more than eight decades ago from the first proposed optical sensor in 1983. However, sensing the environmental variation considering transverse modes is still require the attention from the scientist. Here, for the first time, by considering steering of guided light a high-performance SPR sensor base on Otto structure is proposed. By incorporating the graphene and white graphene in to a prism-waveguide configuration, we calculated the excitation of both TE(TM) modes as refractive index is changed from 1 to 1.04. to analysis of the structure finite-difference time-domain (FDTD) is applied. To benchmark of the structure performance parameters including sensitivity, figure of merit, polarization extinction ratio (PER), and insertion loss (IL) are calculated. Numerical results show that maximum sensitivity and figure of merit are obtained for TM modes of 1226 and 27 respectively. In such a case, graphene monolayer is applied. By considering coupling condition, at the μc?=?0.4 eV, the maximum value of PER is 75 dB, and IL is 0.022 dB. Moreover, it is obtained that in all these conditions PER is higher than 8 dB, and IL is less than 0.04 dB.
相似文献In this report, a novel D-shaped long-range surface plasmon resonance (LRSPR) fiber base sensor has been introduced. The demonstration of proposed sensor involves two D-shaped silver-coated models to study the sensitivity responses. The entire study with the constructed models is based on a single-mode fiber. The models are multilayered consisting of metal, dielectric, and analyte as separate layers. Silver (Ag) and magnesium fluoride (MgF2) strips are used as metal and dielectric layers respectively. The constituency of analyte as an interface excellently standardized the models for sensitivity detection. In this report, a large range of analyte refractive indices (RI) which varies from 1.33 to 1.38 is appraised for the proposed models to characterize the sensitivity. The entire context is encompassed by the wavelength region from 450 to 850 nm with an interval of 20 nm. Sensitivities in this report are measured based on the analyte position from the core and metal for both models. For each of the two models, the analyte is placed as the top layer. RIs of the applied metal (Ag) are measured using the Drude-Lorentz formula. The simulated sensitivities for model-1 and model-2 vary from 6.3?×?103 nm/RIU to 8.7?×?103 nm/RIU.
相似文献The development of diagnostic factors for such neurodegenerative disorders as Alzheimer’s disease is hindered by several limitations that are often witnessed in the early detection of biomarkers in cerebrospinal fluid (CSF) and bio-fluids in clinical contexts. Therefore, here, we suggest a highly sensitive plasmonics nanobiosensor for detection of Alzheimer on one nanodevice through the excitation of surface plasmon resonance (SPR) depending on graphene chemical potential, called a nanobiosensor. This plasmonic nanobiosensor consists of only graphene metasurfaces and samples but does not need extra approaches for the exact analysis of the sample refractive index. Under FDTD simulation, we analyze the sensitivity of 3900 l/RIU for amyloid-beta (Aβ) and figure of merit of 138. This is the first high-performance plasmonics nanobiosensor to monitoring of Alzheimer samples which can be used to detect Alzheimer easily in the future.
相似文献We present a theory for the calculation of the low energy intraband plasmon frequencies and the electron energy loss (EEL) spectra of single layer and multilayer graphene sheets. Our calculation shows that the number of plasmons that can be excited is equal to the number of graphene layers in the sample. One of these is the dominant in-phase plasmon having a square root dependence on the wave number at low wave vectors, whereas the others are out-of-phase plasmons having near linear dependences on the wave number. The EEL spectra of a single layer graphene shows a single peak at the plasmon frequency, which has been observed experimentally. The EEL spectra of all multilayer graphenes have two peaks, one corresponding to the dominant in-phase plasmon and the other due to the out of phase plasmons. We predict that careful measurement of the EEL of multilayer graphene will show both peaks due to the low energy intraband plasmons.
相似文献We propose a highly sensitive refractive index sensor based on the surface phonon resonance (SPhR) in the mid-IR spectral range. Surface phonon polaritons (SPhPs) are formed on polar dielectrics such as SiC in mid-IR wavelength range and can be excited with the help of a metallic grating at specific wavelength termed as resonance wavelength. The resonance wavelength of SPhP is significantly affected by the refractive index of the analyte medium placed over the grating. This forms the basis of a refractive index sensor. We have numerically evaluated the performance of such an SPhP-based refractive index sensor by using rigorous coupled wave analysis (RCWA) in terms of sensitivity, detection accuracy, and quality factor. The quality factor and detection accuracy of the sensor formed on SiC substrate are found to be 225.1 RIU–1 (inverse of refractive index unit) and 6.75, respectively. We have also extended the study for other polar dielectric substrates cBN and GaN and observed considerable enhancement in the performance of the sensor for GaN. The values of quality factor and detection accuracy could be increased to 361.2 RIU–1 and 10.84, respectively, by using GaN substrate. The proposed sensor finds applications in refractive index sensing of liquids and biomolecules having refractive index in the range 1.33–1.36.
相似文献In this study, we propose a surface plasmon resonance (SPR)-based biosensor using silicon nitride (Si3N4), black phosphorous (BP), and thiol-tethered DNA as a ligand for fast detection of the SARS-CoV-2 virus. In the proposed biosensor, we have deposited silver (Ag), Si3N4, and BP on the base of the BK-7 prism and investigated the performance parameters on the probe in different combinations of the mentioned materials. Herein, three (Ag, Si3N4, and BP) different configurations are introduced and compared for the detection of SARS-CoV-2. Furthermore, with the help of the transfer matrix method (TMM), all the three configurations have been analyzed. Notably, the combination of Ag, Si3N4, and BP shows better sensitivity (154°/RIU) when compared with other configurations for the detection of SARS-CoV-2. This work may facilitate a new sensing device to detect SARS-CoV-2, based on the hybrid materials.
相似文献In the present work, a novel surface plasmon resonance (SPR) sensor consisting of the nickel (Ni) film with hybrid structure of blue phosphorene (BlueP)/transition metal dichalcogenides (TMDCs) is reported. By optimizing the thickness of Ni layer and BlueP/TMDCs, the maximum sensitivity with 270°/RIU for the Ni-BlueP/WS2 is achieved. Use of BlueP/TMDCs layer facilitates the sensitivity due to its high electron concentration, high mobility, optical, and electronic properties. Compared with the conventional Ni-based SPR sensor, the sensitivity of the proposed one is enhanced up to ~ 60.7%. We hope that the SPR sensor has potential application prospects in chemical detection, medical diagnostic, optical sensing, etc. due to its high sensitivity.
相似文献We theoretically propose a surface plasmon resonance (SPR)-based fiber optic refractive index (RI) sensor. A surface plasmon exciting metallic grating formed with the alternation of indium tin oxide (ITO) and silver (Ag) stripes is considered on the core of the fiber. A thin film of silicon is used as an overlay. Silicon film not only protects the metallic grating from oxidation but also enhances the field to improve the device sensitivity. The sensor is characterized in terms of sensitivity, detection accuracy (DA), figure of merit (FoM), and quality factor (QF). The maximum sensitivity in the RI range 1.33 to 1.38 refractive index unit (RIU) is reported to be?~25 µm/RIU in infra-red region of investigation.
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