We propose a highly efficient Surface Plasmon Resonance (SPR)-based sensing device to detect various anaemic conditions in human blood. A thin aluminum (Al) metal-coated glass prism is used to excite surface plasmons. A high-dielectric constant material, TiO2, is used over Al-metal to enhance the sensitivity, and a layer of fluorinated graphene (FG) is used as a bio-recognition element to study biomolecular interactions. To demonstrate sensing application, an Al (30 nm)-based engineered plasmonic device with an optimized value of TiO2 (2nm) and functionalized with an FG layer is utilized to detect various hemoglobin (Hb) concentrations in human blood at a wavelength of 1550 nm. A value of sensitivity of 123 °/RIU and FOM 439 RIU-1 is observed for the proposed Al-TiO2-FG-based SPR sensor. The proposed sensing device can be used as a biosensor to detect anemia by accurately evaluating the level of Hb concentration, making it the best candidate for biomedical applications.
This work reports the high-resolution aluminum (Al)-based plasmonic devices in the near-infrared region with incorporation of metamaterials. Our quantitative findings under angle interrogation reveal a notable enhancement in the detection accuracy and quality factor due to incorporating a metamaterial layer over conventional plasmonic structures. The proposed final plasmonic device comprises a Metal-Dielectric-Metal (MDM) configuration with Al metal and Barium Titanate (BTO) as the high dielectric constant material. A monolayer of molybdenum disulfide (MoS2) serves as the binding medium and is utilized to increase the adsorption of biomolecules on the sensor surface. The engineered plasmonic device is used for the detection of cervical (HeLa), blood (Jurkat), adrenal (PC12), and breast (MDA-MB-231 and MCF-7) cancer cells and offers a sensitivity of 101.2 o/RIU and a figure of merit of 5060 RIU-1. The integration of metamaterials into plasmonic sensors holds transformative potential for the field of biomedical sensing.
We present a high-quality factor plasmonic biosensor with a metal-2D material-metal (M-2D-M) structure for dengue detection. The modified prism-based plasmonic sensor consists of two layers of aluminum (Al) (30 nm and 7 nm) sandwiching a layer of 2D nanomaterial (MoS2). Each layer of the proposed plasmonic device is engineered using the transfer matrix method, considering critical performance parameters such as sensitivity, quality factor, detection accuracy, and Figure of Merit (FOM). The effect of different 2D nanomaterial layers, e.g., antimonene, black phosphorus, graphene, MXene, and molybdenum disulfide (MoS2), on the sensing parameters is studied in the M-2D-M structure. A monolayer of MoS2 is considered at the top of the M-2D-M structure as a bio-recognition element to study biomolecular interactions. The final plasmonic multilayer structure, Al-MoS2-Al-MoS2, is used for dengue detection by capturing the variation in different blood components, such as plasma, platelets, and hemoglobin, in normal and infected states.
We present surface plasmon resonance-based sensing devices with Aluminum (Al) as the plasmonic metal in the near-infrared region and analyze the output performances in terms of higher sensitivity and the Figure of Merit (FOM). The optical characteristics of Al-based plasmonic sensors are explored using different interrogation modes (angle and wavelength). Biorecognition elements help to enhance the sensor’s performance, for which 2D nanomaterials are explored for the biofunctionalization of the top surface. In the end, we also present an Al-based plasmonic device that utilizes both prism and nanostructure-based configurations, and the same designed parameters for the device offer high sensitivity and FOM in both angle and wavelength interrogation.
Dielectric and metallic metasurfaces are proposed to demonstrate the sensing applications in the near-infrared region under normal incidence light. The geometrical parameters of the proposed metasurfaces are designed using Rigorous coupled analysis under wavelength interrogation, and the results are verified using Comsol Multiphysics software. A layer of 2D nanomaterial (MoS2) is considered to increase the adsorption on the sensing surface. Aluminum-based metallic metasurfaces offer a sensitivity of 1100nm/RIU with a figure of merit of 250 RIU-1. The proposed metasurfaces are further used for the detection of cancer cells in human blood, and a red shift in the wavelength spectra is observed due to the increase in the refractive index.
We engineer an Aluminum (Al)-based plasmonic device coated with TiO2 and SiO2 layers for biosensing applications. First, the thicknesses of TiO2, SiO2, and Al layers are optimized under the angle interrogation scheme for a wavelength of 1550 nm. Over an optimized value of TiO2, SiO2, and Al film thickness, the variation trend in the performance parameters is studied for a range of thicknesses of 2D nanomaterials for the biofunctionalization of the sensing surface. Later, with the optimized intermediate layers, we present a comparative analysis of Al-based Kretschmann configuration with Graphene, MoS2, MXene, and Fluorinated Graphene. It is observed that the TiO2-SiO2-Al-Fluorinated Graphene-based plasmonic device provides enhanced sensing parameters (sensitivity =120°/RIU, Figure of Merit = 430 RIU-1).
Aluminum-Graphene based plasmonic sensor has been proposed for bio-sensing applications and analyzed for the resonant angle interrogation in the communication band. The addition of the graphene layer above a thin Aluminum metal layer, separated by a high index dielectric Silicon layer is considered. The performance parameters such as sensitivity, reflectivity-amplitude, and figure of merit are analyzed and compared with the conventional plasmonic sensors for the wavelength of 1550 nm. The combination of graphene and silicon layer leads to stronger interactions with biomolecules along with improved sensitivity. The simulated results show that the increase in the number of graphene layers helps to further increase the sensitivity of the biosensor. The maximum sensitivity observed for the plasmonic device was found to be 131°/RIU at the wavelength of 1550 nm.
Periodic plasmonic nanostructures on a thin homogeneous metal layer are used to excite surface plasmons (SPs) for normal incident light in the optical communication band. The structures are engineered using rigorous coupled-wave analysis by considering sensitivity, linewidth, and reflection amplitude as the evaluation parameters. The presence of SP mode at the thin metal–substrate interface in the proposed plasmonic device adds a self-reference capability while capturing the minute refractive index and thickness variations. The wavelength shift in SP mode at the nanostructure–analyte interface is used to measure the changes in the refractive index of the analyte, and the number of waveguide modes is used to capture the changes in the thickness of the analyte. The proposed engineered plasmonic nanostructures offer a sensitivity of 1100 nm/refractive index unit and a resonance line width of 18 nm while taking into account the fabrication constraints. The proposed structures are further simulated for the detection of hemoglobin concentration (using its refractive index measurement) in human blood in the optical communication band (1450 to 1520 nm). The normal incident action eases the integration of engineered plasmonic substrate with optical fibers that can be used both to excite SP and to interrogate the spectral reflectance.
A plasmonic device with a self-referenced capability that uses periodic nanostructures has been proposed and analyzed in terms of the spectral response. Aluminum-based periodic nanostructures that scatter incoming radiation towards a thin homogeneous metal layer, are used to excite Surface Plasmons (SP) for normal incident light. The rigorous coupled wave analysis method is used to engineer the periodic nanostructures and evaluation of performance parameters. The sensitivity, figure of merit and reflective amplitude are considered as the main parameters for engineering the device. The electromagnetic field simulations reveal the presence of waveguide mode and two plasmonic modes, namely, SP mode and substrate mode with three different interactions in the device. The shift in SP mode is used to detect the minute changes in the refractive index of the analyte and the number of exciting waveguide modes is used to capture the changes in the thickness of the analyte. The presence of substrate mode adds the self-reference capability to the proposed plasmonic device due to the independence of any change in the refractive index and thickness of the analyte. The proposed device has been engineered to offer a competitive sensitivity of 1000 nm/RIU and figure of merit 300 RIU-1 with the fabrication constraints taken into account. Since the proposed structures work under normal incidence conditions which makes this design integrable to the end of an optical fiber that can be used both to excite SP and to interrogate the spectral reflectance.
We imaged polarization rotation of transmitted light in 1D Periodic Plasmonic Structures (PPS) fabricated on thin metal coated dielectric substrate. Several PPS of 50% duty cycle and extremely low aspect ratio (height to width ratio) of 0.1 were designed using rigorous coupled wave analysis to exhibit transmission plasmonic resonances at optical wavelengths (400 nm to 700 nm). PPS were fabricated using electron beam lithography, evaporation and lift-off process on glass substrates coated with thin metal. The PPS were characterized using normally incident broadband visible light and crossaxis Polarizer Analyzer setup, with the transmitted light imaged in direct and momentum space using a camera. When the cross axis Polarizer Analyzer were positioned at +45° & -45° respectively w.r.t. plane of incidence, bright emissions of Green, Yellow or Red colors corresponding to transmission plasmonic resonances of the PPS with different periods, were observed in both direct and Fourier planes, instead of completely dark images. From the measured emission momentum in Fourier plane images and spectra of collected light, the emissions were attributed to the excitations of surface plasmons and the reason for surface plasmon excitation in this arrangement is strong coupling of hybrid modes with each other caused by the anisotropy introduced by grating which strongly enhances the efficiency of Polarization rotation. The presented structures behave as frequency selective half wave plates in transmission configuration and could also be used to eliminate the effect of direct beam while imaging the coupling to surface plasmons in periodic structures.
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