Multiple Fano Resonances in Plasmonic Waveguide Based Cavity and Detection of Pathogenic Virus

A technique is implemented for the generation of multiple Fano-resonances in a plasmonic waveguide based rectangular cavity. A rectangular cavity provides four Fano peaks which can further be increased to nine by inserting the metallic bars in it. The trapped surface plasmon polaritons by metallic bars cause the generation of multiple Fano peaks over the wavelength range of 450 nm - 1300 nm. The obtained response is validated through Fano profile and Fano shape parameter is calculated for each resonance peak. The performance of the proposed device is numerically studied as refractive index sensor and method for analyzing the detection of pathogenic virus like SARS-Cov-2 is reported. Out of nine Fano peaks, the best values of sensing performance indices are obtained with full-width, half-maxima of 1.7 nm, quality factor of 405, sensitivity of 1145.71 nm/RIU and figure of merit of 393.25 RIU-1. IEEE

Numerical Investigation on Silicon based Hollow Core Photonic Crystal Fiber for sensing Multiple Virus

In recent years, spread of infection due to virus became whirlwind and creates threat to life in multiple ways. Hence there is in need to sense virus as early as possible in easier way. In this work we propose a multi virus sensor which senses IBV, H5N1, H9N2, and H4N6.Very low refractive index is sensed in this work with increased birefringence due to its elliptical core, where the samples are infiltrated. Numerical analysis is done using Finite Element Method. Among these 4 viruses, IBV has higher sensitivity, birefringence and lower confinement loss which belong to COVID family.88.56% of sensitivity is obtained at 1550nm with low confinement loss. © 2022 IEEE.

Analysis of Compounding and Broadband Extinction Properties of Novel Bioaerosols

Artificially prepared microbial spores have excellent electromagnetic attenuation properties due to their special composition and structure. At present, studies on the optical properties of microbial spores have mainly focused on those with a single band or a single germplasm, which has limitations and cannot reveal the optical properties comprehensively. In this paper, 3 kinds of laboratory-prepared microbial spores were selected for compounding, and the spectral reflectivities of single-germplasm biospores and compound biospores were measured in the wavebands of 0.25–2.4 and 3–15 μm. The complex refractive indices (CRIs) were calculated in combination with the Kramers–Kronig (K-K) algorithm. Relying on the smoke box broadband test system, the transmittance of single-germplasm bioaerosols and compound bioaerosols from the ultraviolet (UV) band to the far-infrared (FIR) band was measured, and the mass extinction coefficients were calculated. The results indicate that the trend of the complex refractive indices of the compound spores is consistent with that of the single-germplasm spores with a larger particle size. For the single-germplasm bioaerosols, the lowest transmittance values were 2.21, 5.70 and 6.27% in the visible (VIS), near-infrared (NIR) and middle-infrared (FIR) bands, and the mass extinction coefficients reached 1.15, 0.87 and 0.84 m2/g, respectively. When AO and BB spores were compounded at 4:1, the extinction performance of the bioaerosols somewhat improved in all wavebands. These results can help to comprehensively analyze the optical properties of bioaerosols and provide ideas for the development of new extinction materials.

Refractive index based optically transparent biosensor device design for early detection of coronavirus.

For the quick detection of the new Coronavirus (COVID-19), a highly sensitive D-shaped gold-coated surface Plasmon resonance (SPR) biosensor is presented. The COVID-19 virus may be quickly and accurately identified using the SPR-based biosensor, which is essential for halting the spread of this excruciating epidemic. The suggested biosensor is used for detection of the IBV i.e. infectious bronchitis viruses contaminated cell that belongs to the family of COVID-19 having a refractive index of - 0.96, - 0.97, - 0.98, - 0.99, - 1 that is observed with the change in EID concentration. Some important optical parameter variations are examined in the investigation process. Multiphysics version 5.3 with the Finite element method is used for the proposed biosensor. The proposed sensor depicts maximum wavelength sensitivity of 40,141.76 nm/RIU. Some other parameters such as confinement loss, crosstalk, and insertion loss are also analyzed for the proposed sensor. The reported minimum insertion loss for the refractive index (RI) - 1 is 2.9 dB. Simple design, good sensitivity, and lower value of losses make the proposed sensor proficient for the detection of infectious bronchitis viruses belonging to COVID-19.

A Loop-Mediated Isothermal Amplification (Lamp)-Based Point-of-Care System for Rapid on-Site Clinical Detection of Sars-Cov-2 Viruses

In the ongoing COVID-19 pandemic, sensitive and rapid on-site detection of the SARS-CoV-2 coronavirus has been one of crucial objectives. A point-of-care (PoC) device called PATHPOD for quick, on-site detection of SARS-CoV-2 employing a real-time reverse-transcription loop-mediated isothermal amplification (RT-rLAMP) reaction on a polymer cartridge. The PATHPOD consists of a standalone device (weighing under 1.2 kg) and a cartridge, and can identify 10 distinct samples and 2 controls in less than 50 minutes. The PATHPOD PoC system is fabricated and clinically validated for the first time in this work © 2023 IEEE.

Sensitivity enhanced tunable plasmonic biosensor using two-dimensional twisted bilayer graphene superlattice

This study theoretically demonstrated an insight for designing a novel tunable plasmonic biosensor, which was created by simply stacking a twisted bilayer graphene (TBG) superlattice onto a plasmonic gold thin film. To achieve ultrasensitive biosensing, the plasmonic biosensor was modulated by Goos-Hänchen (GH) shift. Interestingly, our proposed biosensor exhibited tunable biosensing ability, largely depending on the twisted angle. When the relative twisted angle was optimized to be 55.3°, such a configuration: 44 nm Au film/1-TBG superlattice could produce an ultralow reflectivity of 2.2038 × 10-9and ultra-large GH shift of 4.4785 × 104μm. For a small refractive index (RI) increment of 0.0012 RIU (refractive index unit) in sensing interface, the optimal configuration could offer an ultra-high GH shift detection sensitivity of 3.9570 × 107μm/RIU. More importantly, the optimal plasmonic configuration demonstrated a theoretical possibility of quantitatively monitoring severe acute respiratory syndrome coronavirus (SARS-CoV-2) and human hemoglobin. Considering an extremely small RI change as little as 3 × 10-7RIU, a good linear response between detection concentration of SARS-CoV-2 and changes in differential GH shift was studied. For SARS-CoV-2, a linear detection interval was obtained from 0 to 2 nM. For human hemoglobin, a linear detection range was achieved from 0 to 0.002 g/L. Our work will be important to develop novel TBG-enhanced biosensors for quantitatively detecting microorganisms and biomolecules in biomedical application. © 2023 the author(s), published by De Gruyter, Berlin/Boston 2023.

Breaking the transverse-magnetic polarized light emission bottleneck of AlGaN LED using nano-patterned substrates and Al reflector

Ultraviolet light-emitting diodes based on Al-rich AlGaN semiconductors operating in the 210 nm-280 nm have drawn significant interest for many critical applications, including water purification, disinfection of air and surface as preventive measures of SARS COV-2, sterilization, etc. However, for the above-mentioned applications, the current technology still relies on toxic and inefficient mercury-based UV lamps. Driven by the immense need for an efficient, mercury-free, compact alternative technology, future water purification and disinfection technologies require the development of high-efficiency UV-C light-emitting diodes. To date, the external quantum efficiency (EQE) in AlGaN quantum well (QW) UV-LED heterostructures has been severely limited due to several factors including large densities of defects/dislocations, extremely low light extraction efficiency (LEE) of dominant transverse magnetic (TM) light, absorptive p -GaN contact, and total internal reflection (TIR). © 2022 IEEE.

Study of Ge-As-Se system with high refractive index for infrared glass molded lens

For chalcogenide-based infrared glass materials, the need was emphasized along with the spread of thermal imaging cameras in COVID 19 environment. Commercial Ge-As-Se glass system exhibits a dispersion value of 100 similar to 180 and a refractive index of 2.5 or more, and is suitable for the glass molding process, so it is used as an aspherical infrared lens for various thermal imaging cameras. However, some compositions are not suitable for glass molding process. In this study, the composition of the long wavelength infrared glass melting was designed based on the Ge-As-Se system with a Ge composition range of 0 similar to 35 at%, As composition range of 20 similar to 40 at%, and Se composition range of 25 similar to 60 at%. As a result of XRD analysis for each Ge-As-Se-based composition, it was confirmed that all amorphous grains were obtained in the developed composition area. For the Ge-As-Se glass-forming composition region, the glass transition temperature ranged from 180 to 425 degrees C. The refractive index was measured using the prism method in the 3 to 12 mu m wavelength band. The refractive index (lambda=10 mu m) of Ge5As40Se55 and Ge5As35Se60 was 2.6913 and 2.6538, respectively. Moldability test was performed using a glass molding press. As a result of observing whether the lens has internal defects and microcracks after molding, it was confirmed that there was no abnormality and that it was suitable for glass molding process.

Detection of SARS-CoV-2 Nucleocapsid Protein Using Si Microring Resonator Biosensor

In this study, a fabricated silicon (Si) microring resonator biosensor was able to detect 500 fg/mL of the SARS-CoV-2 nucleocapsid protein in phosphate-buffered saline. The relationship between the amount of wavelength shift and refractive index change is investigated in this work. © 2022 IEICE.

SARS-CoV-2 PROTEINS AND BIOTOXIN DETECTION USING PHOTONIC RESONATOR SENSOR

The great advances in silicon photonic-sensing technology have made it an attractive platform for wide sensing applications. The small size of chip and detection system makes photonic microring resonator can be used in clinic for quick detection of disease. Here, we employ the high sensitivity of the photonic sensor toward the change of refractive index for the detection of SARS-CoV-2 virus spike proteins and botulinum toxin in water. The system require very small amount of sample 50uL with high sensitivity, in short 1hr without pre-treatment required. The measurement can be automatic with minimum manpower involved. Moreover, the system can be multiplexed to detect a few target analytes at the same time in one sample. © 2021 MicroTAS 2021 - 25th International Conference on Miniaturized Systems for Chemistry and Life Sciences. All rights reserved.

Numerical approach to design the graphene-based multilayered surface plasmon resonance biosensor for the rapid detection of the novel coronavirus

In this article, a graphene-based multilayered surface plasmon resonance (SPR) biosensor of (BK7/WS2/Au/BaTiO3/Graphene) is proposed for the rapid detection of the novel coronavirus (COVID-19). The proposed SPR biosensor is designed based on the angular interrogation attenuated total reflection (ATR) method for rapid detection of the COVID-19 virus. The sensor's surface plasmon polaritons (SPPs) and the sensing region refractive index (RI) are changed, owing to the interaction of various concentrated ligand-analytes. The specific ligand is mechanized with the proposed sensor surface and the target analyte that has flowed onto the sensing surface. The proposed sensor is capable of detecting the COVID-19 virus rapidly in two different ligand-analytes environments, such as: (i) the virus spike receptor-binding domain (RBD) as an analyte and monoclonal antibodies (mAbs) as a probe ligand, and (ii) the monoclonal antibodies (IgG or IgM) as an analyte and the virus spike RBD as a probe ligand. Due to the binding of the target ligand-analytes, the concentration level of the sensing region is incremented. As the increment in the concentration level, the RI of the sensing medium increases, therefore the change in RI causes the shift in the SPR angle resulting in the output reflectance intensity. The performance of the multilayered SPR sensor is analyzed numerically using the finite element method (FEM) method. Numerically, the proposed sensor provides the maximum angular shift sensitivity at 230.77 deg/refractive index unit (RIU), detection accuracy (DA) at 0.161 deg(-1), and the figure of merits (FOM) is at 37.22 RIU-1. In addition, with each additional graphene layer number (L), the proposed sensor exhibits the angular shift sensitivity increment (1 + 0.7L) times. The novelty of the proposed multilayer (BK7/WS2/Au/BaTiO3/Graphene) sensor is highly angular sensitivity, and capable of detecting the COVID-19 virus rapidly without a false-positive report. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Graphene-metasurface-based biosensor for SARS-CoV-2 detection

The COVID-19 pandemic attributed to the SARs-Cov-2 virus has disrupted the lives of individuals in every corner of the world, causing millions of infections and numerous deaths worldwide. Identifying and isolating infected people is very crucial to slow down the spread of the disease. In this paper, we report a design of highly sensitive, graphene-metasurface based biosensor for detecting the S1 spike protein expressed on the surface of the SARSCoV-2 virus in the terahertz band. Our structure consists of a silicon dioxide substrate sandwiched between a complete gold layer at the bottom, and a graphene monolayer on top etched with a phi-shaped slot tilted at 45 degree, which performs a wideband reflective-type cross-polarization conversion of the incident electromagnetic (EM) wave. The optimized polarization conversion ratio (PCR) has been achieved at 0.75eV chemical potential value of the graphene layer. When samples of Sars-CoV-2 virus contained in a phosphate buffer saline (PBS) solvent is put on top of proposed design of the sensing surface, the spike proteins of the virus interact with the spike antibody grown on the sensing surface;and it changes the refractive index of the overall system (Biosensor + Analyte), which in turn changes the PCR and the corresponding frequency of the reflected wave. The biosensor response has been computed using the Finite Integration Technique (FIT) in the terahertz region. The sensitivity of the biosensor is found to be 354 GHz/RIU at the PCR of 0.9. © COPYRIGHT SPIE. Downloading of the is permitted for personal use only.

ALCOHOL GEL FOR ASEPSY OF THE HANDS-PROPER FORMULATION AND GUARANTEED EFFICIENCY AMID THE PANDEMIC OF COVID-19

The use of hand antiseptics became widespread as a routine in the fight against COVID-19. In the market, the availability and purchase of substandard antiseptics create a permanent concern with safety, even after a pandemic. Therefore, the development of easy-to-deploy analytical methods for the quality control of alcohol-based hand antiseptics is needed. In this work, to determine the ethanol content in alcohol gel the use of refractometry and alcohol oxidation method by dichromate accompanied by UV-Vis spectroscopy were applied. The results indicated that 19 brands (out of the 70 evaluated) (27.1%) had levels of ethyl alcohol below the recommended level (68.25%), therefore, they are ineffective for hand asepsis. For the quality control of hand antiseptics, refractometry and the oxidation-reduction reaction are complementary analytical methodologies. As a quick, inexpensive screening method, refractometry provides a more suitable technique. However, the interference of emollients may affect the accuracy of the ethanol content determination. Therefore, applying the ethanol oxidation method coupled with electronic spectroscopy offers a simple and broadly accessible method to confirm the ethanol content in alcohol-based hand antiseptics. In addition to developing quality control protocols, is also described the 3.5-ton production of alcohol gel at the Federal University of Bahia.

The Development of Point-of-Care Plasmonic-based Biosensor for Early Detection of COVID-19 Virus

The current impact of COVID-19 on global health and the economy is enormous. Considering pandemic severity, there is an urgent need to develop a smart biosensor that can provide early detection of SARS-CoV-2 viruses with robust and reliable results. In this work, we have systematically developed a plasmonic-based biosensor chip for the early detection of the COVID-19 virus by providing fast and reliable results. The label-free plasmonic sensor utilizes light and detects the resonance oscillation of surface-bound free conduction electrons in the presence of the target analyte biomarker (virus), resulting in binding and affinity incidents at the surface of plasmonic gold (Au) material, causing a shift in the resonance wavelength. The results show the ability of biosensor to exhibit an increased shift in the resonance wavelength upon binding of the COVID-19 virus because of the change in the optical property, i.e., the refractive index of the medium in the vicinity of the Au film. This study further demonstrated the fabrication and performance optimization of the plasmonic biosensor for the potential point-of-care testing device. © 2021 IEEE.

Viruses Such as SARS-CoV-2 Can Be Partially Shielded from UV Radiation When in Particles Generated by Sneezing or Coughing: Numerical Simulations

UV radiation can inactivate viruses such as SARS-CoV-2. However, designing effective UV germicidal ir- radiation (UVGI) systems can be difficult because the effects of dried respiratory droplets and other fomites on UV light intensities are poorly understood. Numerical modeling of UV intensities inside virus- containing particles on surfaces can increase understanding of these possible reductions in UV intensity. We model UV intensities within spherical approximations of virions randomly positioned within spherical particles. The model virions and dried particles have sizes and optical properties to approximate SARS- CoV-2 and dried particles formed from respiratory droplets, respectively. In 1-, 5- and 9-m diameter par- ticles on a surface, illuminated by 260-nm UV light from a direction perpendicular to the surface, 0 , 10 and 18 (respectively) of simulated virions are exposed to intensities less than 1/100 th of intensities in individually exposed virions (i.e., they are partially shielded). Even for 302-nm light (simulating sunlight), where absorption is small, 0 and 11 of virions in 1- and 9-m particles have exposures 1/100 th those of individually exposed virions. Shielding is small to negligible in sub-micron particles. Results show that shielding of virions in a particle can be reduced by illuminating a particle either from multiple widely separated incident directions, or by illuminating a particle rotating in air for a time sufficient to rotate through enough orientations. Because highly UV-reflective paints and surfaces can increase the angular ranges of illumination and the intensities within particles, they appear likely to be useful for reducing shielding of virions embedded within particles.

Surface plasmon resonance biosensor with laser heterodyne feedback for highly-sensitive and rapid detection of COVID-19 spike antigen.

The ongoing outbreak of the COVID-19 has highlighted the importance of the pandemic prevention and control. A rapid and sensitive antigen assay is crucial in diagnosing and curbing pandemic. Here, we report a novel surface plasmon resonance biosensor based on laser heterodyne feedback interferometry for the detection of SARS-CoV-2 spike antigen, which is achieved by detecting the tiny difference in refractive index between different antigen concentrations. The biosensor converts the refractive index changes at the sensing unit into the intensity changes of light through surface plasmon resonance, achieving label-free and real-time detection of biological samples. Moreover, the gain amplification effect of the laser heterodyne feedback interferometry further improved the sensitivity of this biosensor. The biosensor can rapidly respond to continuous and periodic changes in the refractive index with a high resolution of 3.75 × 10-8 RIU, demonstrating the repeatability of the biosensor. Afterwards, the biosensor is immobilized by the anti-SARS-CoV-2 spike monoclonal antibodies, thus realizing the specific recognition of the antigen. The biosensor exhibited a high sensitivity towards the concentration of the antigen with a linear dynamic range of five orders of magnitude and a resolution of 0.08 pg/mL. These results indicate that this principle can be used as a rapid diagnostic method for COVID-19 antigens without sample labelling.

Development of a novel label-free all-fiber optofluidic biosensor based on Fresnel reflection and its applications.

A novel, compact, cost-effective, and robust label-free all-fiber optofluidic biosensor (LF-AOB) based on Fresnel reflection mechanism was built through integrating single-multi mode fiber coupler and highly sensitive micro-photodetector. The Fresnel reflection light intensity detected by the LF-AOB greatly depended on the RI change on the end-surface of the fiber probe according to experimental and simulation results. The capability of the LF-AOB for real-time in situ detection in optofluidic system were verified by measuring salt and protein solution, and the lowest limit of detection was 1.0 × 10-6 RIU. Our proposed theory can effectively eliminate the influence of light intensity fluctuation, and one-point calibration method of sensor performance is conducive for rapid and convenient detection of targets. Label-free sensitive detection of SARS-Cov-2 Spike protein receptor-binding domain (S-RBD) and the binding kinetics assay between S-RBD and anti-S-RBD antibody were achieved using the LF-AOB. These contributed to the elegant design of all-fiber optical system with high efficiency, high resolution and sensitivity of micro-photodetector, and enhanced interaction between the light and the samples at the liquid-sensor interface because of the large surface area of the multi-mode fiber probe. The LF-AOB can be extended as a universal sensing platform to measure other factors associated with refractive index because its high sensitivity, low sample consumption (∼160 nL), and capability of real-time in situ detection.