Department of Electrical and Electronics Engineering
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Item Investigation of 2D nanomaterials on MXene (Ti3C2Tx)-based aluminum plasmonic devices for biosensing in the near-infrared region(Springer, 2022-08) Arora, PankajIn this work, we have engineered Aluminum (Al)-based plasmonic devices with MXene (Ti3C2Tx) nanosheet to achieve both high sensitivities as well Figure of Merit (FOM) simultaneously for the wavelength of 1550 nm in the optical communication band. Since, studying 2D nanomaterials can provide quality collaboration for Ti3C2Tx, from their functionalization to application; Black Phosphorus, Graphene, fluorinated Graphene, and MoS2 are undertaken for this purpose. The effect of such 2D nanomaterials has been studied on both sensitivity and FOM for Ti3C2Tx-based engineered Al-plasmonic devices and a decent value of both sensitivity (119°/RIU) and FOM (340RIU−1) is achieved in the Kretschmann’s configuration. To demonstrate the bio-sensing application with the proposed plasmonic devices, the detection of protein solution concentration, based on the change in their refractive indices, is carried out. The proposed Ti3C2Tx-based Al-plasmonic devices show promising applications in the optical communication band, employing fluorinated graphene and MoS2 in the near-infrared region.Item Fourier plane colorimetric sensing using broadband imaging of surface plasmons and application to biosensing(AIP, 2015-12) Arora, PankajWe demonstrate an optical technique for refractive index and thickness sensing of sub-wavelength-thick dielectric analytes. The technique utilizes the broadband, multimode, directional leakage radiation arising from the excitation of hybrid mode surface plasmons (SP) on low aspect ratio periodic plasmonic substrates with period ≈λ. The approach requires relaxed fabrication tolerances compared to extra ordinary transmission-based sensing techniques, wherein minor shifts in the fabricated dimensions result in a very large change from the designed resonant wavelength. We show that refractive index perturbations due to about 10-nm-thick dielectric can be captured optically by the usage of carefully designed plasmonic substrates, a halogen lamp source, free-space optical components, polarizers, and a low-end, consumer-grade charge coupled device camera. The plasmonic substrates were designed for converting the signature of hybrid mode SP excitation into a transmission peak by utilizing a thin homogeneous metal layer sandwiched between the periodic plasmonic structures and the substrate. The resonance is highly sensitive to the refractive index and thickness of the analyte superstrate. The excitation of hybrid mode SP results in a polarization rotation of 90° of the leaked radiation at resonant wavelength. In order to eliminate the problem of image registration (i.e., placing the same feature in the same pixel of the image, for comparison before and after a change in refractive index) for sensing, we perform the color analysis in the Fourier plane. The change in color of the bright emitted spot with highest momentum, corresponding to the leakage of fundamental SP mode, was used to measure the changes in refractive index, whereas the number and color of spots of lower momenta, corresponding to higher-order Fabry Perot modes, was used to measure the variation in thickness. We further show that the Fourier plane analysis can also be used to sense the index of thicker dielectrics, where real plane image analysis may fail to sense index perturbations, simply due to superposition of different modes in the real plane images of such substrates. Control experiments and analysis revealed a refractive index resolution of 10–5 RIU. The results were correlated with simulations to establish the physical origin of the change in the fundamental mode and higher-order modes due to the refractive index and thickness of analyte. As a demonstration of an application and to test the limits of sensing, the substrates were used to image the surface functionalization using 2-nm-thick 11-mercaptoundecanoic acid and immobilization of 7-nm-thick mouse anti-human IgG antibody. In biological systems, where a priori knowledge about a process step is available, where accurate chemical composition testing is not necessary or possible, the presented method could be used to study the surface changes using a label-free sensing mechanism.Item Graphene decorated aluminum-nanostructure based plasmonic device with enhanced sensitivity and figure of merit using both wavelength and angle interrogation(Elsevier, 2022-07) Arora, PankajIn this work, we have proposed graphene decorated Aluminum (Al) nanostructure-based plasmonic device for sensing in the near-infrared region where the same engineered plasmonic device can be used under both angle as well as wavelength interrogation with high sensitivity and Figure of Merit (FOM) simultaneously. A detailed analysis using rigorous coupled-wave analysis is carried out to prove the feasibility of the proposed plasmonic device with the same designed parameters to operate in two interrogation modes, which is impossible in conventional prism configuration. The performance parameters, sensitivity, and FOM are found to be 1000 nm/RIU and 333.33RIU−1 during wavelength interrogation and 119º/RIU and 318.91RIU−1 for the angle interrogation respectively. Finally, the biosensing application is carried out by demonstrating the glucose concentration detection in the urine samples. The proposed Al-based plasmonic device decorated with graphene layer has the advantages of being cost-effective and possessing real-time sensing capability, paving the way for biomedical applications in the near-infrared region.