Fiber Optic Sensor For Detection Research Articles

A highly sensitive refractive index based etched optical fiber sensor for detection of human sperm

Human sperm functionality is one of the important factors for continuing natural reproduction, but due to the variation in environmental factors, its infertility is increased. Such agitating characteristics need the use of sophisticated computer-aided devices, whose precision is not up to the mark, especially for the samples with a low concentration of sperms. Therefore, for the first time, a gold-graphene oxide capped etched optical fiber sensor is presented in this paper for the refractive index (RI) based detection of human sperm samples. The sensor takes the advantage of evanescent waves, which are excreting from the etched region, to sense the analytes. In this work, the sensing analysis is done by considering two different sensor structures, such as core-gold-sperm and core-gold-graphene oxide-sperm. The wavelength compatibility of sensor structures is examined by performing the sensing at 520 nm and 633 nm wavelengths. For the sensing process, the sperm samples of ten different people are collected with their concentration and mobility, and their RIs are obtained by using the ATAGO refractometer. The results are evaluated in terms of transmission spectra, sensitivity, quality factor, and figure of merit (FOM). The obtained results demonstrate that the core-gold-graphene oxide-sperm sensor structure is very efficient at the wavelength of 633 nm with the sensitivity, quality factor, and FOM of 203.72°/RIU, 27.055 RIU−1 and 27.309, respectively.

Fiber Optic Sensors for Detection of Sodium Plating in Sodium-Ion Batteries

Fiber Optic Sensors for Detection of Sodium Plating in Sodium-Ion Batteries

Chitosan-Integrated Single-Mode Tapered Optical Fiber DENV II E Protein Sensor

This work reports the enhancement of a single-mode tapered optical fiber (TOF) sensor for Dengue virus (DENV) II E protein using chitosan. Chitosan, an organic nanomaterial with excellent biocompatibility and abundant binding sites, was deposited on TOF as an intermediate layer between the activated taper surface and the anti-DENV II E protein antibodies. The best DENV sensing performance was attained at chitosan thickness of 17.13 nm, which was attributed to the optimum balance between the auxiliary layer thickness and penetration depth of the evanescent field. An enhanced sensitivity value of 14.19 nm/nM was achieved compared to the sensitivity obtained by standard configuration sensor. A lower dissociation constant, K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">d</sub> of 1.00×10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-10</sup> M was also acquired, which implies a higher affinity towards the targeted E protein. Findings from this work highlight the potential of organic nanomaterial such as chitosan for biosensor enhancement and further emphasize the capability of fiber optic sensors for detection of dengue virus as well as other antigens.

Electroluminescent optical fiber sensor for detection of a high intensity electric field

On-line testing of high power electromagnetic devices is one of the most important problems of modern industrial metrology. In the paper, the results of experimental investigations of the electric field optical fiber sensor based on the electroluminescent phenomena are presented. The electro¬luminescent effect is observed in some composite semicon¬ductors, among others in zinc sulfide ZnS crystals. In our investigations, the used ZnS crystal was doped with copper Cu atoms as activators. The concentration of activator in the ZnS crystal was about 5.10-4 [g/g]. According to plans of investi¬gations of the elaborated electroluminescent sensor, the spectral properties as well as the intensity of light emission in sinusoidal alternating electric field were tested.Full Text: PDF

A comparative analysis of all fiber optic sensors for detection of adulteration in fossil fuels

Refractive index is directly proportional to the concentration of medium. Based on this principle, we report two schemes of measuring varying concentration of solvent by measuring output response through intensity interrogation. In the first case, we use evanescent field by exposing certain portion of a cladding to varying concentration of fossil fuels. In the second case, we utilize reflectance through a displacement scheme for measuring the same analyte. Accordingly, all results are comprehensively analyzed and all sensing performances are procedurally investigated. The sensitivity of both the schemes are estimated and compared. The evanescent fiber optic set-up renders better response as compared to the displacement one. Due to simplicity in design approach, the all fiber optic schemes prove to be highly adaptable to sense other chemical contaminants.

CdS coated clad-modified fiber optic sensor for detection of NO2 gas

In this investigation, a clad-modified fiber optic sensor is reported for NO2 gas detection. CdS is coated over cladding-removed region by Chemical Bath Deposition (CBD) which acts as the gas-sensing medium. CdS is coated over four fibers each with a different coating duration of 10, 20, 30 and 40 min. Characterisation of CdS is done by Scanning Electron Microscope (SEM), Energy-dispersive x-ray spectroscopy (EDX), x-ray Diffraction (XRD), Photoluminescence study (PL) and UV-visible absorption spectroscopy. The spectral response for different concentrations of NO2 is studied on the four fibers separately, and it is analysed.

Carbon Dot-functionalized Interferometric Optical Fiber Sensor for Detection of Ferric Ions in Biological Samples.

This work reports an interferometric optical microfiber sensor functionalized with nitrogen- and sulfur-codoped carbon dots (CDs) for the detection of ferric ions (Fe3+). Compared to other CD-based ferric ion sensors, the sensing mechanism of this presented sensor is dependent on the refractive index modulations due to selective Fe3+ adsorption onto the CD binding sites at the tapered region. This is the first study in which CD-based sensing was performed at the solid phase as a chelator, which does not rely on its fluorescence properties. The detection performance of the proposed sensor is not only comparable to a conventional fluorescence-based CD nanoprobe sensor but also capable of delivering quantitative analysis results and ease of translation to a sensor device for on-site detection. The presented sensor exhibits Fe3+ detection sensitivity of 0.0061 nm/(μg/L) in the linear detection range between 0 and 300 μg/L and a detection limit of 0.77 μg/L based on the Langmuir isotherm model. Finally, the potential use of the CD-functionalized optical microfiber sensor in the real environmental and biological Fe3+ monitoring applications has also been validated in this work.

Simulation and performance evaluation of fiber optic sensor for detection of hepatic malignancies in human liver tissues

A fiber optic sensor is proposed for the identification of healthy and cancerous liver tissues through determination of their corresponding refractive index values. Existing experimental results describing variation of complex refractive index of liver tissues in near infrared (NIR) spectral region are considered for theoretical calculations. The intensity interrogation method with chalcogenide fiber is considered. The sensor’s performance is closely analyzed in terms of its sensitivity at multiple operating wavelengths falling in NIR region. Operating at shorter NIR wavelengths leads to greater sensitivity. The effect of design parameters (sensing region length and fiber core diameter), different launching conditions, and fiber glass materials on sensor’s performance is examined. The proposed sensor has the potential to provide high sensitivity of liver tissue detection.

Multimode Fiber Optic Sensor for Adulterant traces in Edible Oil using Nanotechnology Technique

Fiber optic sensors for detection and determination of adulterant traces in edible oil is designed in the laboratory. The fundamental principle of detection is the sensitive dependence of the wavelength shift due to the refractive index changes of the surrounding medium of multimode fiber cladding. Building up of this low cost multimode fiber optic sensor is helpful in detection and determination of adulteration in oils. Fiber optic sensor coupled with gold-nanoparticles shows an enhancement in the sensitivity of designed sensor in the determination of concentration of adulteration in coconut oil.

High sensitivity sol-gel silica coated optical fiber sensor for detection of ammonia in water.

A high sensitivity ammonia sensor based on a tapered small core singlemode fiber (SCSMF) structure for measurement of ammonia concentration in water is reported. Two tapered SCSMF fiber structures with different waist diameters of 23 µm and 13.5 µm are fabricated by using a customized microheater brushing technique. The silica based material prepared by the sol-gel method is used as a coating applied to the surface of the tapered fiber structures. To investigate the influence of the coating thickness on the sensitivity to ammonia in water, silica coatings with different thicknesses (2-pass and 8-pass coatings) are deposited on the surface of the fiber sensor with a waist diameter of 23 µm. Experiments demonstrate that the sensor with a thicker (8-pass) silica coating shows better sensitivity of 0.131 nm/ppm to ammonia compared to that of 0.069 nm/ppm for the thinner silica coating (2-pass). To further improve the sensor sensitivity, the taper waist diameter is reduced. For an 8-pass coating (249nm at the taper waist section) applied to a tapered SCSMF structure based fiber sensor with a reduced waist diameter of 13.5 µm. Experimental results show that the sensitivity to ammonia is significantly improved to 2.47nm/ppm. The best measurement resolution for ammonia concentration in water is estimated to be 4 ppb while the response and recovery times are less than 2 and 5 minutes respectively. The proposed sensor also offers good performance in terms of repeatability and good selectivity for sensing ammonia compared to that of other common ions and organic molecules in water.

Suspended-core microstructured fiber for refractometric detection of liquids.

A silica suspended-core microstructured optical fiber sensor for detection of liquids, operating at 1550nm, is analyzed. The sensing principle is based on the evanescent wave overlap into a tested analyte, which is filled via capillary forces into the cladding holes. Validations for analytes in the refractive index range of 1.35-1.43 are carried out with liquid-analyte-filling-length limits being studied both theoretically and experimentally. We prove, for the first time to our knowledge, that an extreme sensitivity of 342.86dB/RIU and resolution of 4.4×10-5 can be achieved. This sensor represents a high-quality alternative for applications requiring a facile, low-cost solution.

Fiber optic sensor modified by grafting of the molecularly imprinted polymer for the detection of ammonium in aqueous media

Subject of Research.The paper deals with novel chemical sensors based on the polymeric optical fibers modified by grafting of the molecularly imprinted polymer for the detection of ammonium in aqueous solutions. Elevated concentrations of ammonium in surface waters lead to their eutrophication, that’s why, monitoring of the content of this ion is very important for the evaluation of surface water quality. However, currently in situ monitoring of relevant parameters in surface waters is constrained by the availability and cost of commercial sensors. Attractive approach to the development of chemical sensors for remote controls is the use of polymeric optical fibers. Polymer optical fibers have high mechanical resistance and low cost, and give the possibility for multiplexing and remote sensing. Method. Polymeric layer imprinted with ammonium ions was grafted on the surface of the methylmethacrylate fiber. Methacrylic acid was used as a monomer, ethylene glycol dimethacylate as a cross-linker, 2.2'-Azobis (2-ethylpropionamidine) dihydrochloride as a radical initiator, ammonium as a template and water:ethanol 4:1 mixture as a solvent. Optimization of the imprinted polymer synthesis conditions was carried out using intensity of transmitted light, uniformity of the grafted polymeric layer and response in the aqueous ammonium solutions as optimization criteria. Main Results. Chemical sensors based on the polymeric optical fibers modified by grafting of the molecularly imprinted polymer for the detection of ammonium in aqueous solutions have been developed. New method of the grafting of the molecularly imprinted polymer on the surface of the methylmethacrylate optical fiber has been developed. It was found out, that high concentrations of the monomer and cross-linker in the polymerization solutions cause optical fiber damage while longer polymerization times result in the decrease of the intensity of transmitted light. Optical sensor demonstrating response to ammonium in the aqueous solutions was obtained using the following experimental conditions: methacrylic acid – 2.1 mmolL-1, ethylene glycol dimethacylate – 7.7 mmolL-1 and NH4Cl – 0.3 mmolL-1 and polymerization time equal to15 minutes. Practical Relevance. Results obtained in this work are applicable in the ecological monitoring of ammonium in the surface waters, in particular, as a part of remote in situ sensing systems. Furthermore, developed optimized method of the grafting of molecularly imprinted polymer on the surface of the polymeric optical fiber is usable for the development of fiber optic sensors for detection of other compounds.

Evanescent wave DNA-aptamer biosensor based on long period gratings for the specific recognition of E. coli outer membrane proteins

An evanescent wave fiber optic sensor for detection of Escherichia coli (E. coli) outer membranes proteins (EcOMPs) using long period gratings (LPGs) as a refractometric platform is presented. The sensing probes were attained by the functionalization of LPGs inscribed in single mode fiber using two different methods of immobilization; electrostatic assembly and covalent binding. The resulting label-free configuration enabled the specific recognition of EcOMPs in water by monitoring the resonance wavelength shift due to refractive index changes induced by binding events. The sensors displayed linear responses in the range of 0.1nM to 10nM EcOMPs with sensitivities of −0.1563±0.005nmdecade−1 [EcOMP, M] (electrostatic method) and −0.1597±0.004nmdecade−1 [EcOMP, M] (covalent method). The devices could be regenerated (under low pH conditions) with a deviation less than 0.1% for at least three subsequent detection events. The sensors were also applied to spiked environmental water samples.

Refractometric Fiber Optic Sensor for Detecting Salinity of Water

Salinity is an important property of industrial and natural waters. It is defined as the measure of the mass of dissolved salts in a given mass of solution. High salinity has an impact on people and industries reliant on water. High levels of salt can reduce crop yields, limit the choice of crops that can be grown and, at higher concentrations over long periods, can kill trees and make the land unsuitable for agricultural purposes. Salinity increases the “hardness” of water, which can mean more soap and detergents have to be used or water softeners installed and maintained. This can also cause scaling in pipes and heaters. The experimental determination of the salt content by drying and weighing presents some difficulties due to the loss of some components. The only reliable way to determine the true or absolute salinity of natural water is to make a complete chemical analysis. However, the method is time consuming and cannot yield the precision necessity for accurate work. Thus to determine salinity, one normally used method involves the measurement of a physical property such as conductivity, density or refractive index. The paper reports the refractometric fiber optic sensor for detection of salinity of water. The mathematical model is developed for detection of the refractive index of liquid and simulated in MATLAB. The fiber optic sensor probe is developed to measure the refractive index of the solution containing different amount of salt dissolved in water i.e. different molar concentrations. Experiments are carried out using the developed probe for these solutions. Experimental results are showing good agreement with the simulated results.

Highly specific fiber optic immunosensor coupled with immunomagnetic separation for detection of low levels of Listeria monocytogenes and L. ivanovii

BackgroundImmunomagnetic separation (IMS) and immunoassays are widely used for pathogen detection. However, novel technology platforms with highly selective antibodies are essential to improve detection sensitivity, specificity and performance. In this study, monoclonal antibodies (MAbs) against Internalin A (InlA) and p30 were generated and used on paramagnetic beads of varying diameters for concentration, as well as on fiber-optic sensor for detection.ResultsAnti-InlA MAb-2D12 (IgG2a subclass) was specific for Listeria monocytogenes and L. ivanovii, and p30-specific MAb-3F8 (IgM) was specific for the genus Listeria. At all bacterial concentrations (103–108 CFU/mL) tested in the IMS assay; the 1-μm diameter MyOne beads had significantly higher capture efficiency (P < 0.05) than the 2.8-μm diameter M-280 beads with both antibodies. The highest capture efficiency for MyOne-2D12 (49.2% for 105 CFU/mL) was significantly higher (P < 0.05) than that of MyOne-3F8 (16.6 %) and Dynabeads anti-Listeria antibody (9 %). Furthermore, capture efficiency for MyOne-2D12 was highly specific for L. monocytogenes and L. ivanovii. Subsequently, we captured L. monocytogenes by MyOne-2D12 and MyOne-3F8 from hotdogs inoculated with mono- or co-cultures of L. monocytogenes and L. innocua (10–40 CFU/g), enriched for 18 h and detected by fiber-optic sensor and confirmed by plating, light-scattering, and qPCR assays. The detection limit for L. monocytogenes and L. ivanovii by the fiber-optic immunosensor was 3 × 102 CFU/mL using MAb-2D12 as capture and reporter antibody. Selective media plating, light-scattering, and qPCR assays confirmed the IMS and fiber-optic results.ConclusionsIMS coupled with a fiber-optic sensor using anti-InlA MAb is highly specific for L. monocytogenes and L. ivanovii and enabled detection of these pathogens at low levels from buffer or food.

Development of a fluorosiloxane polymer-coated optical fibre sensor for detection of organic volatile compounds

A compact optical fibre sensor coated with a fluorosiloxane polymer has been shown to be suitable for monitoring of some different classes of organic volatile compounds (VOCs), namely some chlorinated hydrocarbons, aromatic hydrocarbons, aliphatic hydrocarbons, acetate and alcohols. The sensing component consists of an optical fibre, with the top end surface coated with poly[methyl(3,3,3-trifluoropropyl)siloxane] by dip-coating technique. Variations of the light power guided through the fibre are detected as the organic vapour is sorbed in the thin polymeric film. The experimental set-up is further constituted by an optical source to generate the interrogating signal and a photodiode to measure the intensity modulated signal. In this work some operational conditions such as, temperature of cure of the polymeric material, injection cell temperature, carrier gas flow rate, laser working wavelengths and frequencies were studied in order to achieve higher sensitivity and accuracy concerning sensor system performance. High detection capability for volatile organic compounds, good sensibility, reversibility, reproducibility and linearity were analytical features checked for this sensor system. However, the main advantage of the developed sensor is its very short analytical time (response time and desorption time), found to be less than 20 s. Compounds well known as potentially dangerous for human health and environment, such as toluene and benzene showed changes on the reflected optical power up to 26.0 and 4.0 dB, respectively.

Detection of Volatile Organic Compounds Based on Optical Fibre using Nanostructured Films

Abstract An optical fibre sensor for detection of volatile organic compounds (VOCs) has been implemented. This device is based on a vapochromic material presented in the form of bright red powders, which suffers reversible changes in its optical properties when exposed to some organic vapours. The sensor head consists of a nano interferometer doped with the vapochromic material, built onto a cleaved ended multimode optical fibre by using the Layer by Layer Electrostatic Self Assembly Method (LbL). A reflection scheme was used, so the intensity modulated reflected signal is registered in order to study its response. Changes up to 3 dB in the reflected optical power were measured.

Volatile alcoholic compounds fibre optic nanosensor

A fibre optic sensor for detection of some volatile organic compounds (VOCs) is presented. This device is based on a new vapochromic material of formula [Au2Ag2(C6F5)4(C6H5N)2], presented in the form of bright red powders. This material changes its optical properties as colour or refractive index when exposed to some organic vapours, recovering its original state when vapours get disappeared. The sensor head consists of a nanometer-scale Fizeau interferometer doped with the vapochromic material, built onto a cleaved end of a multimode fibre optic pigtail by using the electrostatic self-assembly method (ESA). The fibre optic sensor is used in a reflection scheme, so the other extreme of the optical fibre pigtail is connected to an optical coupler, completing the set-up with an optical source that generates an interrogating signal and an optical detector to register the intensity modulated reflected measure. The response of the sensor has been characterized taking measures of its absorbance spectra and the intensity modulated reflected signal at 850nm for different alcohols. Changes up to 3dB in the reflected optical power were registered.

Fiber Optic Sensors for Detection of Corrosion within Aircraft

The cost of preventing and controlling corrosion in aging aircraft fleets is becoming a significant burden. Early detection of corrosion will reduce the maintenance required to repair the damage, which should result in increased aircraft availability and significant reduction in the cost of ownership. Fluorescent fiber optic sensors that detect aluminum cations from the early stages of the corrosion process are proposed as a means for providing early warning of corrosion in susceptible areas of an aging aircraft. This article will discuss the results for two different carriers of an aluminum-sensing fluorophore and some of the key technical issues that need to be resolved for the development of an effective fiber optic sensing system.

RAPTOR: A fluoroimmunoassay-based fiber optic sensor for detection of biological threats

The RAPTOR was developed to meet the need for a small, portable, easily operated biosensor for the detection of biological threats in the field. This device has evolved over a number of years to reach its current level of maturity. This paper describes details of the RAPTOR's design, including the recent upgrades to the fluidics and optics subsystems, as well as design improvements that have increased both system reliability and sensitivity. Working with these system upgrades, we also investigated biochemical methods that further improve assay sensitivity. The use of NeutrAvidin/biotin chemistry to improve immobilization of the capture antibody, coupled with use of the fluorophore Alexa Fluor 647 to label the tracer antibody, has resulted in a two- to four-fold signal enhancement. These gains, in combination with redesigned optics and instrumentation, have resulted in approximately a log-order improvement over earlier systems. These improvements are shown for an assortment of analytes of interest, including Staphylococcal enterotoxin type-B, Francisella tularensis, Bacillus anthracis, and Bacillus globigii spores.