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Dewen Duan - One of the best experts on this subject based on the ideXlab platform.

Francisco J. Arregui - One of the best experts on this subject based on the ideXlab platform.

  • a comprehensive review materials for the fabrication of optical fiber Refractometers based on lossy mode resonance
    Sensors, 2020
    Co-Authors: Aritz Ozcariz, Carlos Ruizzamarreno, Francisco J. Arregui
    Abstract:

    Lossy mode resonance based sensors have been extensively studied in recent years. The versatility of the lossy mode resonance phenomenon has led to the development of sensors based on different configurations that make use of a wide range of materials. The coating material is one of the key elements in the performance of a refractometer. This review paper intends to provide a global view of the wide range of coating materials available for the development of lossy mode resonance based Refractometers.

  • high sensitive lossy mode resonance based optical fiber Refractometers by means of sputtered indium oxide thin films
    Smart Sensors Actuators and MEMS VII; and Cyber Physical Systems, 2015
    Co-Authors: P. Sánchez, Miguel Hernaez, K. Gonzalez, Carlos Ruíz Zamarreño, Ignacio R. Matias, Francisco J. Arregui
    Abstract:

    ABSTRACT Three different optical fiber Refractometers based on lossy mode resonances (LMRs) have been fabricated by means of the deposition of indium oxide thin-films. The sensitivity of the devices as well as the full-width at half maximum (FWHM) has been characterized as a function of the surrounding medium refractive index (from 1.332 to 1.471. Obtained results revealed that thinner coating possess higher sensitivities. However, the FWHM is better for thicker coatings. As a general rule, the thicker the In 2 O 3 coating the lower the sensitivity, but the better the FWHM. Thus, a compromise is required depending on the necessities of the application. Keywords: Optical fiber, Refractometer, Indium oxide, DC - Sputtering 1. INTRODUCTION Different optical fiber sensing applications have been developed in fields like biomedical, chemical and environmental monitoring. One of the most interesting groups of optical fiber sensors are those based on spectral response because their response is highly immune to fluctuations of the optical source power. This kind of optical fiber sensors are represented mostly by the groups based on long-period gratings [1], fiber Bragg gratings [2], interferometers [3] or resonances [4]. In the last few years, optical fiber Refractometers have attr acted the attention of many authors as a promising label-free sensing platform. Lossy Mode Resonances (LMRs) have been recently described by our group as a novel type of resonances that present several remarkable and interesting pr operties, such as independence with the polarization of light or easy generation of multiple resonances [5]. Additionally, LMRs can be generated by using a wide range of materials from transparent conductive oxides [6-7] to polymeric films [8] or hybrid polymer/metal oxide nanoparticle coatings [9]. LMRs shift as a function of the refractive index of the medium in contact with the supporting layer and enable the fabrication of highly sensitive Refractometers [6, 9]. Here, it is first described the fabrication of LMR-based optical fiber Refractometers by means of the deposition of a thin indium oxide (In

  • SnO2 based optical fiber Refractometers
    OFS2012 22nd International Conference on Optical Fiber Sensors, 2012
    Co-Authors: P. Sánchez, Miguel Hernaez, Carlos Ruíz Zamarreño, I. Del Villar, Ignacio R. Matias, Francisco J. Arregui
    Abstract:

    ABSTRACT In this work, the fabrication and characterization of Refractometers based on lossy mode resonances (LMR) is presented. Tin dioxide (SnO 2 ) films deposited on optical fibers are used as the LMR supporting coatings. These resonances shift to the red as a function of the external refractive index, enabling the fabrication of robust and highly reproducible wavelength-based optical fiber Refractometers. The obtained SnO 2 -based refractometer shows an average sensitivity of 7198 nm/refractive index unit (RIU) in the range 1.333–1.420 RIU. Keywords: Optical fiber; LMR; Refractive index; Refractometer; Tin oxide; dip-coating 1. INTRODUCTION Measurement of refractive index (RI) is needed in different areas. For this reason, many RI sensors have been proposed for several applications, including industrial process monitoring, quality control in the food industry, and biomedical applications. The Abbe refractometer is a well-known standard apparatus to measure RI in the visible and near-IR spectrum [1, 2]. However, some limitations of traditional Refractometers, such as size and weight, have made necessary the development of novel devices. A field of research has focused on optical fibers sensors to measure RI. Optical fiber Refractometers are a promisi ng and attractive tool in chemical and bi otechnological applications due to their advantages, such as high sensitivity, immunity to electromagnetic interference, compact size and the possibility of remote sensing. In addition to this, different optical fiber architectures and techniques have been used for the fabrication of optical fiber Refractometers, such as polished fibers [3], tapered fibers [4] and hetero-core [5] fibers based on surface plasmon resonances, long-period fiber gratings [6] or cladding removed multi-mode fibers (CRMMF) based on lossy mode resonances (LMRs) [7-10]. Concretely in the field of LMRs, previous works have studied the advantages of the utilization of these resonances [9] and the properties of the coatings in order to obtain the adequate conditions to produce LMRs [10]. LMRs can be produced by means of the fabrication of a metal oxide coating onto the optical fiber core core, more details about this phenomenon can be found in th e literature [7-10, 14]. In this work, an optical fiber refractometer based on Lossy M ode Resonances (LMR) is presented. More specifically, this work is focused on the fabrication of LMR-based Refractometers based on tin dioxide (SnO

  • optical fiber Refractometers based on indium tin oxide coatings fabricated by sputtering
    Optics Letters, 2012
    Co-Authors: S Lopez, Miguel Hernaez, I. Del Villar, Francisco J. Arregui, Ruiz C Zamarreno, Ignacio R. Matias
    Abstract:

    This Letter presents the fabrication of optical fiber Refractometers based on indium tin oxide (ITO) coatings deposited by sputtering with response in the visible region. ITO thin films have been sputtered by means of a rotating mechanism that enables the fabrication of smooth and homogeneous coatings onto the optical fiber core. The ITO coating acts as a resonance supporting layer. This permits us to couple light from the waveguide to the ITO-coating/external medium region at specific wavelength ranges. The device is sensitive to external medium refractive index, which allows its utilization as a refractometer. The sensitivity is dependent on the coating thickness, ranging from 523.21 to 1221 nm/refractive index unit in the explored sensors. The sensor development process is time effective compared to other techniques such as dip coating or layer-by-layer self-assembly, which is interesting in terms of mass production.

Apriyanto Haris - One of the best experts on this subject based on the ideXlab platform.

  • Analysis and Design of a Hybrid Optical Fiber Refractometer for Large Dynamic Range Measurements
    'Institute of Electrical and Electronics Engineers (IEEE)', 2020
    Co-Authors: Apriyanto Haris, Ernal Olivie, Cattoe Michel, Lizio Françoise, Sharp James, Surre Frédéric, Chavagnac Valérie, Seat, Ha Cheng
    Abstract:

    International audienceA fiber refractometer with large dynamic range from 1.316 to 1.61 RIU has been realized using a hybrid configuration of a single-mode fiber (SMF) coupled to a stripped-cladding multimode fiber (MMF) as sensing element. An extended analysis of the diffraction principle of a Gaussian beam is specifically developed for this sensor configuration to determine the injected power density into the MMF which, when subsequently combined with ray optics, analytical wave optics and Fresnel equations, enables the sensor response to be comprehensively estimated. Simulation results have been experimentally corroborated to very high agreement for a 2-cm and a 5-cm decladded section of multimode fiber used as the sensing element. The results show, for the shorter sensor (2 cm), a very high sensitivity of ~-250 a.u./RIU being achieved in the Zone II operating regime, i.e. for indices between the cladding and core indices together with a resolution of 2.76×10-6 RIU being attained. In addition, the developed models have been used to accurately predict the response of sensing elements of various lengths, hence demonstrating the potential capability of this research to be exploited for optimizing bespoke design of fiber Refractometers of any arbitrary sensing lengths or dimensions. As an example, we present the design of a refractometer achieving a maximum sensitivity of 300 a.u./RIU with a potential resolution of 2.26 ×10-6 RIU

  • Analysis and design of a hybrid optical fiber refractometer for large dynamic range measurements
    'Institute of Electrical and Electronics Engineers (IEEE)', 2020
    Co-Authors: Apriyanto Haris, Surre Frédéric, Chavagnac Valérie, Bernal, Olivier D., Cattoen Michel, Lizion Francoise, Sharp, James H., Seat, Han Cheng
    Abstract:

    A fiber refractometer with large dynamic range from 1.316 to 1.61 RIU has been realized using a hybrid configuration of a single-mode fiber (SMF) coupled to a stripped-cladding multimode fiber (MMF) as sensing element. An extended analysis of the diffraction principle of a Gaussian beam is specifically developed for this sensor configuration to determine the injected power density into the MMF which, when subsequently combined with ray optics, analytical wave optics and Fresnel equations, enables the sensor response to be comprehensively estimated. Simulation results have been experimentally corroborated to very high agreement for a 2-cm and a 5-cm decladded section of multimode fiber used as the sensing element. The results show, for the shorter sensor (2 cm), a very high sensitivity of ~ -250 a.u./RIU being achieved in the Zone II operating regime, i.e. for indices between the cladding and core indices together with a resolution of 2.76 × 10 -6 RIU being attained. In addition, the developed models have been used to accurately predict the response of sensing elements of various lengths, hence demonstrating the potential capability of this research to be exploited for optimizing bespoke design of fiber Refractometers of any arbitrary sensing lengths or dimensions. As an example, we present the design of a refractometer achieving a maximum sensitivity of 300 a.u./RIU with a potential resolution of 2.26 × 10 -6 RIU

  • Etudes, analyse et validation expérimentale des réfractomètres à fibres à base de fibres monomodes, multimodes et à cristaux photoniques pour la mesure de l'indice de réfraction avec application pour la détection du gaz méthane
    HAL CCSD, 2019
    Co-Authors: Apriyanto Haris
    Abstract:

    National audienceRefractive index measurement has been studied since Ernest Abbé initially designed a refractometer in 1869, which is named the Abbé refractometer. Since then, numerous types of Refractometers have been developed by employing either the optical prism-based refractometer or the optical fiber-based refractometer, due to their wide-ranging applications such as for sensing various physical, biological and chemical parameters. Recently, a large number of researchers have been developing Refractometers based on optical fibers, exploiting mechanisms such as surface plasmon resonance (SPR), multimode interference, fiber Bragg gratings (FBG), long-period gratings (LPG), tapered optical fibers, and striped-cladding multimode fibers (MMFs), for their advantages in immunity against electromagnetic interference, electrical passivity at the sensing probe, and capability to long term in situ measurement. This thesis concerns the development of comprehensively functional and accurate models for optical fiber Refractometers based on optical intensity modulation, in particular for stripped-cladding MMF refractometry as well as hybrid systems involving a combination of single-mode-multimode fiber refractometery and the all-fiber hybrid refractometer using photonic crystal fibers. A key objective of this work is to characterize the performance of these intensity-based optical fiber Refractometers in terms of their power response, sensitivity, resolution, and dynamic range. The simulation results which are corroborated experimentally demonstrate very high sensitivity being obtained in Zone II (i.e. the sensing regime typically employed for measuring a sensing medium index higher than the cladding index but less than or equal to the core index) for all three types of Refractometers. However, the sensitivity in Zone III (i.e. the sensing regime for which the sensing medium index is higher than the core index) is very low. A hybrid single-mode fiber - multimode fiber configuration is used to improve the sensitivity in Zone III. On other hand, the sensitivity for Zone I (i.e. the sensing regime typically employed for measuring a sensing medium index lower than the cladding index) has been improved by increasing evanescent wave absorption using the all-fiber hybrid refractometer based on solid-core photonic crystal fibers. As a further potential of the fiber refractometer for applications in biochemical sensing, the proof-of-concept for a methane gas sensor has been demonstrated using supramolecular cryptophane-A which enables to trap the methane molecules. Cryptophane-A incorporated into a functionalized film of Styrene-Acrylonitrile (SAN) host is applied to a de-cladded region of the sensor as the sensitive region. The refractive index of this functionalized layer increases proportionally with increasing methane concentration, subsequently inducing variations in the transmitted optical power along the fiber sensor.La mesure de l'indice de réfraction a été étudiée depuis qu'Ernest Abbé aie initialement conçu un réfractomètre en 1869, appelé le réfractomètre d'Abbé. Depuis lors, de nombreux réfractomètres ont été développés tels que le réfractomètre à prisme optique ainsi que le réfractomètre à fibre optique, en raison de leurs applications étendues pour la détection de divers paramètres physiques, biologiques et chimiques. Récemment, un grand nombre de chercheurs ont mis au point des réfractomètres basés sur des fibres optiques, exploitant des mécanismes tels que la résonance des plasmons de surface (SPR), les interférences multimodes, les fibres à réseaux de Bragg (FBG), les fibres à réseaux à longues périodes (LPG), les fibres optiques coniques et la fibre multimode à gaine dénudée. Les capteurs fibrés sont avantageux grâce à leur immunité contre les interférences électromagnétiques, passivité électrique au niveau de la sonde de détection et potentiel de mesure in situ à long terme. Cette thèse concerne le développement de modèles complets fonctionnels et précis pour les réfractomètres à fibres optiques basés sur la modulation d'intensité optique, en particulier la réfractométrie à fibre multimode à gaine dénudée ainsi que les systèmes hybrides associant fibres monomode et multimode, et un réfractomètre hybride tout fibré utilisant des fibres à cristaux photoniques. L'objectif clé de ce travail est de caractériser les performances de ces réfractomètres à fibres optiques basés sur la modulation d'intensité en termes de réponse en puissance, de sensibilité, de résolution et de dynamique de mesure. Les résultats de simulation qui sont corroborés expérimentalement démontrent que la très grande sensibilité obtenue dans la zone II (c'est-à-dire le régime de détection typiquement utilisé pour mesurer l'indice du milieu supérieur à l'indice de gaine mais inférieur ou égal à l'indice du coeur) pour tous les trois réfractomètres. Cependant, la sensibilité dans la Zone III (c‟est-à-dire le régime de détection pour lequel l‟indice du milieu à mesurer est supérieur à celui du coeur) est très faible. Ainsi, un refractomètre fibré hybride monomode-multimode est utilisé pour améliorer la sensibilité dans la Zone III. D'autre part, la sensibilité pour la zone I (c'est-à-dire le régime de détection pour mesurer l‟indice du milieu inférieur à l'indice de la gaine) a été améliorée en augmentant l'absorption des ondes évanescentes à l'aide du réfractomètre hybride tout fibré à base de fibres à cristaux photoniques à coeur solide. En termes d'application réelle du réfractomètre à fibre pour la détection biochimique, une preuve de concept pour un capteur du gaz méthane a été démontrée en utilisant les supramolécules de cryptophane-A qui permettent de piéger les molécules du méthane. Le cryptophane-A incorporé dans un film hôte à base de styrène-acrylonitrile (SAN) est appliqué sur la zone dénudée du capteur comme une région fonctionnalisée. L'indice de réfraction de cette couche sensible augmente proportionnellement avec l'augmentation de la concentration du méthane, ce qui induit une variation de la puissance optique transmise dans le capteur fibré

  • Étude, analyse et validation expérimentale des réfractomètres fibrès à base de fibres monomodes, multimodes, et à cristaux photoniques pour la mesure de l'indice de réfraction avec application pour la détection du gaz méthane
    2019
    Co-Authors: Apriyanto Haris
    Abstract:

    La mesure de l'indice de réfraction a été étudiée depuis qu'Ernest Abbé aie initialement conçu un réfractomètre en 1869, appelé le réfractomètre d'Abbé. Depuis lors, de nombreux réfractomètres ont été développés tels que le réfractomètre à prisme optique ainsi que le réfractomètre à fibre optique, en raison de leurs applications étendues pour la détection de divers paramètres physiques, biologiques et chimiques. Récemment, un grand nombre de chercheurs ont mis au point des réfractomètres basés sur des fibres optiques, exploitant des mécanismes tels que la résonance des plasmons de surface (SPR), les interférences multimodes, les fibres à réseaux de Bragg (FBG), les fibres à réseaux à longues périodes (LPG), les fibres optiques coniques et la fibre multimode à gaine dénudée. Les capteurs fibrés sont avantageux grâce à leur immunité contre les interférences électromagnétiques, passivité électrique au niveau de la sonde de détection et potentiel de mesure in situ à long terme. Cette thèse concerne le développement de modèles complets fonctionnels et précis pour les réfractomètres à fibres optiques basés sur la modulation d'intensité optique, en particulier la réfractométrie à fibre multimode à gaine dénudée ainsi que les systèmes hybrides associant fibres monomode et multimode, et un réfractomètre hybride tout fibré utilisant des fibres à cristaux photoniques. L'objectif clé de ce travail est de caractériser les performances de ces réfractomètres à fibres optiques basés sur la modulation d'intensité en termes de réponse en puissance, de sensibilité, de résolution et de dynamique de mesure. Les résultats de simulation qui sont corroborés expérimentalement démontrent que la très grande sensibilité obtenue dans la zone II (c'est-à-dire le régime de détection typiquement utilisé pour mesurer l'indice du milieu supérieur à l'indice de gaine mais inférieur ou égal à l'indice du coeur) pour tous les trois réfractomètres. Cependant, la sensibilité dans la Zone (c’est-à-dire le régime de détection pour lequel l’indice du milieu à mesurer est supérieur à celui du coeur) est très faible. Ainsi, un refractomètre fibré hybride monomode-multimode est utilisé pour améliorer la sensibilité dans la Zone III. D'autre part, la sensibilité pour la zone I (c'est-à-dire le régime de détection pour mesurer l’indice du milieu inférieur à l'indice de la gaine) a été améliorée en augmentant l'absorption des ondes évanescentes à l'aide du réfractomètre hybride tout fibré à base de fibres à cristaux photoniques à coeur solide. En termes d'application réelle du réfractomètre à fibre pour la détection biochimique, une preuve de concept pour un capteur du gaz méthane a été démontrée en utilisant les supramolécules de cryptophane-A qui permettent de piéger les molécules du méthane. Le cryptophane-A incorporé dans un film hôte à base de styrène acrylonitrile (SAN) est appliqué sur la zone dénudée du capteur comme une région fonctionnalisée. L'indice de réfraction de cette couche sensible augmente proportionnellement avec l'augmentation de la concentration du méthane, ce qui induit une variation de la puissance optique transmise dans le capteur fibré.Refractive index measurement has been studied since Ernest Abbé initially designed a refractometer in 1869, which is named the Abbé refractometer. Since then, numerous types of Refractometers have been developed by employing either the optical prism-based refractometer or the optical fiber-based refractometer, due to their wide-ranging applications such as for sensingvarious physical, biological and chemical parameters. Recently, a large number of researchers have been developing Refractometers based on optical fibers, exploiting mechanisms such as surface plasmon resonance (SPR), multimode interference, fiber Bragg gratings (FBG), long period gratings (LPG), tapered optical fibers, and striped-cladding multimode fibers (MMF), for their advantages in immunity against electromagnetic interference, electrical passivity at the sensing probe, and capability to long term in-situ measurement. This thesis concerns the development of comprehensively functional and accurate models for optical fiber Refractometers based on optical intensity modulation, in particular for stripped-cladding MMF refractometry as well as hybrid systems involving a combination of single-mode-multimode fiber refractometery and the all-fiber hybrid refractometer using photonic crystal fibers. A key objective of this work is to characterize the performance of these intensity-based optical fiber Refractometers in terms of their power response, sensitivity, resolution, and dynamic range. The simulation results which are corroborated experimentally demonstrate very high sensitivity being obtained in Zone II (i.e. the sensing regime typically employed for measuring a sensing medium index higher than the cladding index but less than or equal to the core index) for all three types of Refractometers. However, the sensitivity in Zone III (i.e. the sensing regime for which the sensing medium index is higher than the core index) is very low. A hybrid single-mode fiber - multimode fiber configuration is used to improve the sensitivity in Zone III. On other hand, the sensitivity for Zone I (i.e. the sensing regime typically employed for measuring a sensing medium index lower than the cladding index) has been improved by increasing evanescent wave absorption using the all-fiber hybrid refractometer based on solid-core photonic crystal fibers. As a further potential of the fiber refractometer for applications in biochemical sensing, the proof-of-concept for a methane gas sensor has been demonstrated using supramolecular cryptophane-A which enables to trap the methane molecules. Cryptophane-A incorporated into a functionalized film of StyreneAcrylonitrile (SAN) host is applied to a de-cladded region of the sensor as the sensitive region. The refractive index of this functionalized layer increases proportionally with increasing methane concentration, subsequently inducing variations in the transmitted optical power along the fiber sensor

Ibrahim Elsohaby - One of the best experts on this subject based on the ideXlab platform.

  • evaluation of 3 Refractometers to determine transfer of passive immunity in neonatal beef calves
    Journal of Veterinary Internal Medicine, 2021
    Co-Authors: Lisa Gamsjager, Ibrahim Elsohaby, Jennifer M Pearson, Michel Levy, E A Pajor, Claire M Windeyer
    Abstract:

    BACKGROUND Refractometry is used to assess transfer of passive immunity (TPI), but studies evaluating different Refractometers and appropriate thresholds for recommended target immunoglobulin G (IgG) concentrations for beef calves are limited. OBJECTIVES To evaluate test performance of digital (DSTP) and optical (OSTP) serum total protein (STP) Refractometers and a digital Brix (DBRIX) refractometer for assessment of passive immunity in beef calves. ANIMALS A total of 398 beef calves from 6 herds, 1 to 7 days of age. METHODS Serum IgG concentration was estimated by DSTP, OSTP, and DBRIX, and measured by radial immunodiffusion (RID). Correlation coefficients (r) among results were calculated. Optimal STP and Brix thresholds for identification of IgG <10, <16, and <24 g/L were determined using interval likelihood ratios. Refractometer performance and agreement were assessed using areas under the curve (AUC), diagnostic test characteristics, Cohen's kappa (κ), and Bland-Altman analysis. RESULTS Refractometer results were highly correlated with RID (r = 0.82-0.91) and with each other (r = 0.91-0.95), and overall test performance was excellent (AUC = 0.93-0.99). The STP concentrations of ≤5.1, ≤5.1, and ≤5.7 g/dL and Brix percentages of ≤7.9%, ≤8.3%, and ≤8.7% indicated IgG concentrations <10, <16, and <24 g/L, respectively. Agreement of Refractometers with RID was variable (κ = 0.46-0.80) and among Refractometers was substantial (κ = 0.62-0.89). CONCLUSIONS AND CLINICAL IMPORTANCE All Refractometers showed good utility as monitoring tools for assessment of TPI in beef calves.

  • usefulness of digital and optical Refractometers for the diagnosis of failure of transfer of passive immunity in neonatal foals
    Equine Veterinary Journal, 2019
    Co-Authors: Ibrahim Elsohaby, Christopher B Riley, J T Mcclure
    Abstract:

    BACKGROUND: Neonatal foals with failure of transfer of passive immunity (FTPI) are at higher risk of morbidity and mortality. Successful treatment of FTPI is time‐dependent, thus rapid and accurate measurement of serum IgG concentration is important for the management and care of neonatal foals. OBJECTIVES: To validate the use of digital and optical Refractometers for assessing FTPI in neonatal foals and compare the diagnostic performance and level of agreement of the two Refractometers to the reference standard radial immunodiffusion (RID) assay. STUDY DESIGN: A retrospective validation study. METHODS: Serum samples (n = 253) were collected from 230 foals admitted to the Veterinary Teaching Hospital and Ambulatory Equine Service between 2012 and 2017. The serum IgG concentrations were measured by the reference RID assay, digital Brix and optical Refractometers. The correlation between results of two Refractometers and RID assay was assessed. A receiver operating characteristic curve was created and used to identify the optimal cut‐offs for evaluating sensitivity and specificity of the two Refractometers to detect foals with complete and partial FTPI. RESULTS: The RID‐IgG concentrations were positively correlated with the Brix scores obtained from a digital refractometer (r = 0.73, P = 0.001) and serum total protein obtained from an optical refractometer (r = 0.72, P = 0.001). The sensitivity and specificity of the digital Brix refractometer at optimal cut‐off (≤7.8% Brix) were 88.1 (95% CI: 74.4–96.0) and 67.7% (95% CI: 60.6–74.3) to detect RID‐IgG<4 g/L and 79.0 (95% CI: 68.5–87.3) and 77.3% (95% CI: 69.8–83.8) to detect RID‐IgG≤8 g/L, respectively. The sensitivity and specificity of the optical refractometer at optimal cut‐off (≤42 g/L) were 86.1 (95% CI: 72.1–94.7) and 70.9% (95% CI: 63.9–77.3) to detect RID‐IgG<4 g/L and at cut‐off (≤44 g/L) were 82.9 (95% CI: 73.0–90.3) and 72.7% (95% CI: 64.8–79.6) to detect RID‐IgG≤8 g/L, respectively. MAIN LIMITATIONS: The number of diseased foals was small to investigate the validity of the selected cut‐off values for assessing FTPI in sick foals. CONCLUSIONS: The two Refractometers exhibit utility as rapid, inexpensive screening tests and have a good sensitivity for assessing FTPI in neonatal foals.

  • using serum and plasma samples to assess failure of transfer of passive immunity in dairy calves
    Journal of Dairy Science, 2019
    Co-Authors: Ibrahim Elsohaby, J T Mcclure, L A Waite, M Cameron, Luke C Heider, Gregory P Keefe
    Abstract:

    The objectives of this study were (1) to determine the differences in IgG and total protein (TP) content of serum and plasma samples collected from the same calves; (2) to evaluate the correlation between calf serum and plasma IgG levels, Brix scores, and TP concentrations; (3) to determine whether different cut-off values should be used for plasma and serum to assess failure of transfer of passive immunity (FTPI) in dairy calves; and (4) to evaluate the level of agreement between results obtained from using serum and plasma samples of the same calves to assess FTPI using optimal cut-off values. Blood samples (n = 217) were collected from Holstein calves at 3 to 10 d of age on 30 commercial dairy farms in Nova Scotia and Newfoundland, Canada. Paired serum and plasma samples were analyzed for IgG concentration by the reference radial immunodiffusion assay, transmission infrared (TIR) spectroscopy, digital and optical Brix Refractometers, and optical TP refractometer. The IgG concentrations measured by RID and TIR spectroscopy in serum were similar to those in plasma. However, the Brix and TP refractometer readings were significantly higher in plasma than in serum. The prevalence of FTPI in serum and plasma samples based on a RID-IgG concentration <10 g/L was 43.3 and 46.5%, respectively. The RID-IgG concentration was correlated with TIR-IgG (r = 0.92 and 0.89), digital Brix (r = 0.80 and 0.80), optical Brix (r = 0.77 and 0.77), and optical TP (r = 0.75 and 0.77) Refractometers in serum and plasma, respectively. The correlations between paired serum and plasma IgG content were 0.85 by TIR spectroscopy, 0.80 by digital Brix, 0.77 by optical Brix, and 0.79 by optical TP refractometer. The optimal cut-off values for TIR spectroscopy, digital Brix, optical Brix, and TP Refractometers to assess FTPI using serum were 13.1 g/L, 8.7% Brix, 8.4% Brix and 5.1 g/dL, respectively; and the optimal cut-off values with plasma were 13.4 g/L, 9.4% Brix, 9.3% Brix and 5.8 g/dL, respectively. When using these optimal cut-off values, the level of agreement (88.1%) between results derived from testing serum and plasma by TIR spectroscopy was substantial, with a kappa (κ) value of 0.76. The results derived from testing serum and plasma by digital Brix refractometer showed substantial agreement (83.4%), with a κ value of 0.65, which is higher than the agreement and κ value (74.7% and 0.51) reported for the optical Brix refractometer. Substantial agreement (81.6%) between serum and plasma TP was also obtained when using the optical TP refractometer, with a κ value of 0.63. In conclusion, serum or plasma samples can be used interchangeably for measuring IgG concentrations and assessing FTPI in dairy calves. However, different cut-offs must be used to assess FTPI depending on the sample matrix. Furthermore, results obtained from serum samples showed higher agreement with the reference RID assay than those obtained from plasma samples.

  • effect of heat treatment on accuracy of infrared spectroscopy and digital and optical brix Refractometers for measuring immunoglobulin g concentration in bovine colostrum
    Journal of Veterinary Internal Medicine, 2018
    Co-Authors: J T Mcclure, Ibrahim Elsohaby, G P Keefe
    Abstract:

    BACKGROUND: Heat-treatment of colostrum is a method developed to reduce calf exposure to pathogens. Infrared (IR) spectroscopy and Brix Refractometers can be used for measuring colostral IgG concentration and assessing colostrum quality. OBJECTIVES: To determine the impact of heat-treatment on accuracy of IR spectroscopy and Brix Refractometers for measuring colostral IgG concentration and assessing colostrum quality before and after heat-treatment. ANIMALS: A total of 60 Holstein dairy cows on 8 commercial dairy farms. METHODS: A cross-sectional study was designed to determine the effect of heat-treatment at 60°C and 63°C each for 30 and 60 minutes duration on colostral IgG concentration measured by the reference radial immunodiffusion (RID) assay, IR spectroscopy, and digital and optical Refractometers. RESULTS: Colostrum IgG concentration significantly decreased after heat-treatment at 63°C for 30 or 60 minutes as measured by RID, but the IgG values remained unchanged when measured by IR spectroscopy and Refractometers. The lowest correlation coefficient found between IR spectroscopy (r = 0.70) and RID results was in colostrum heat-treated at 63°C for 60 minutes. For digital (r = 0.48) and optical (r = 0.50) Refractometers, the lowest correlation coefficient was at 63°C for 30 minutes when compared to RID. The accuracy of the IR spectroscopy, digital and optical Brix Refractometers was decreased from 91.7 to 80%, 81.7 to 45%, and 80 to 45%, respectively, when colostrum heat-treated at 63°C for 60 minutes. CONCLUSIONS AND CLINICAL IMPORTANCE: Radial immunodiffusion, IR spectroscopy, and Brix Refractometers exhibit utility for measuring IgG concentration when colostrum heat-treated at 60°C but does not detect decrease IgG concentrations when heat-treated at 63°C.

  • evaluation of transmission infrared spectroscopy and digital and optical Refractometers to identify low immunoglobulin g concentrations in alpaca serum
    Canadian Journal of Veterinary Research-revue Canadienne De Recherche Veterinaire, 2017
    Co-Authors: Ibrahim Elsohaby, Christopher B Riley, J J Burns, J T Mcclure
    Abstract:

    This study aimed to evaluate the digital Brix and optical serum total protein (STP) Refractometers for measuring concentrations of serum immunoglobulin G (IgG) in alpacas and compare them to IgG concentrations measured by the reference method of radial immunodiffusion (RID) assay. The appropriate cutoff point for Brix and STP Refractometers and the transmission infrared (TIR) spectroscopy method was determined for low IgG concentrations (< 10 g/L). Serum samples were collected from alpacas (N = 169) and tested by both Refractometers. The correlation between Brix % and STP was high [correlation coefficient (r) = 0.99]. However, the correlation coefficients between Brix % and STP with serum RID-IgG concentrations were only 0.56 and 0.55, respectively. Twenty-one (12.4%) of 169 alpaca serum samples had IgG concentrations of < 10 g/L. Using receiver operator characteristic curve (ROC) analysis, the optimal cutoff points for the TIR assay, digital Brix, and optical STP Refractometers for assessing low IgG (RID < 10 g/L) were 13 g/L, 8.8%, and 50 g/L, respectively. The TIR assay showed higher sensitivity (Se = 95.2%) and specificity (Sp = 96.8%) than either the digital Brix (Se = 90.5% and Sp = 65.5%) or optical STP (Se = 81% and Sp = 73.7%) Refractometers for assessing alpacas with low IgG. In conclusion, the Brix and STP Refractometers lack accuracy in measuring alpaca IgG concentrations, but may be useful for screening animals for low serum IgG. However, the TIR assay with a cutoff point of 13 g/L was more appropriate for identifying low IgG than either refractometer. Another study that focuses on neonatal crias is recommended in order to evaluate the usefulness of these assays for field diagnosing of failure of transfer of passive immunity (FTPI).

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