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DIVAKAR, RAMGOPAL. "ROOM TEMPERATURE ADHESIVE BONDING TECHNIQUE FOR MICROFLUIDIC BIOCHIPS." University of Cincinnati / OhioLINK, 2002. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1027950500.
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Owens, Tracie LeeAnne. "Engineering amphiphilic fabrics for microfluidic applications." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/42908.
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Woven textile fabrics were designed and constructed from hydrophilic and hydrophobic spun yarns to give planar substrates containing amphiphilic microchannels with defined orientations and locations. Polypropylene fibers were spun to give hydrophobic yarns, and the hydrophilic yarns were spun from a poly(ethylene terephthalate) copolyester. Water wicking rates into the fabrics were measured by video microscopy and longitudinal wicking tests from single drops and from reservoirs. Intra-yarn microchannels in the hydrophilic polyester yarns were shown to selectively transport aqueous fluids, with the flow path governed by the placement of the hydrophilic yarns in the fabric. Simultaneous wicking of an aqueous and hydrocarbon fluid into the hydrophilic and hydrophobic microchannels of an amphiphilic fabric was successfully demonstrated. The high degree of interfacial contact and micron-scale diffusion lengths of such co-flowing immiscible fluid streams inside amphiphilic fabrics suggest potential applications as highly scalable and affordable microcontactors for industrial liquid-liquid extractions. The efficiency of liquid-liquid extractions carried out with the amphiphilic fabrics was evaluated. Solvent extraction efficiencies were shown to reach up to ~98%.
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Li, Haifeng. "An evanescent-wave based particle image velocimetry technique." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2008. http://hdl.handle.net/1853/26472.
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Thesis (Ph. D.)--Mechanical Engineering, Georgia Institute of Technology, 2009.Committee Chair: Yoda, Minami; Committee Member: Aidun, Cyrus; Committee Member: Breedveld, Victor; Committee Member: Fedorov, Andrei; Committee Member: Zhu, Cheng. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Rabehi, Amine. "Electromagnetic microsystem for the detection of magnetic nanoparticles in a microfluidic structure for immunoassays." Thesis, Sorbonne université, 2018. http://www.theses.fr/2018SORUS129/document.
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La détection et quantification d’agent biologique occupe une place prépondérante dans la prévention et la détection des dangers possibles pour la santé publique (épidémie ou pandémie), l’environnement ainsi que d’autres risques contextuelles (bioterrorisme, armes biologique ou chimiques…etc.). Par conséquent, le développement d’un système portable et à moindre coût permettant de détecter ces dangers constitue l’axe de recherche pluridisciplinaire de la collaboration entre différents laboratoires de l’UPMC (Paris 6) et « RWTH university » à Aachen en Allemagne. Dans ce projet, nous avons étudié les aspects pluridisciplinaires d’un microsystème (LoC) électromagnétique de détection immunologique basé sur l’utilisation de nanoparticules magnétiques (MNP). En raison de leur extractabilité et de leur triabilité, les MNP sont adaptées à l'examen d'échantillons biologiques, servant de marqueurs pour des réactions biochimiques. La plupart des techniques classiques de détection existantes sont basées sur des méthodes colorimétrique, fluorescence ou électrochimique qui souffrent en majorité de problème de temps d’analyse et de sensibilité. A cet égard, Les méthodes d’immuno-détection magnétiques constituent une alternative prometteuse. Cette détection est effectuée à l’aide des MNP qui sont spécifiquement bio-fonctionnalisés en surface afin d’être liée à la cible (virus, anticorps…etc). La nouvelle méthode magnétique de mélange de fréquence permet la détection et la quantification de ces MNP avec une grande dynamique. Dans cette thèse, l’effort est dirigé vers la miniaturisation de ce système. Pour ce faire, nous avons développé un ensemble d’outils analytiques et de simulations multiphysiques afin d’optimiser les dimensions des parties électromagnétique (bobines planaires) et microfluidiques. Par la suite, des prototypes de cette structure de détection à partir de bobines en circuits imprimés et de réservoirs microfluidiques en PDMS sont dimensionnés et réalisés. Les performances de ces prototypes ont été évaluées en termes de limite de détection de MNP, linéarité et plage dynamique. En outre, ces prototypes ont permis de valider les outils de dimensionnement réalisés. Une limite de détection de nanoparticules magnétiques de 15ng/mL a été mesurée avec un volume d'échantillon de 14 μL correspondant à une goutte de sang. Finalement, la validation du système quant à l’immuno-détection est abordée avec un état de l’art et le développement d’une procédure de fonctionnalisation biochimique de surface ainsi que des premiers tests pour sa validationThe detection and quantification of a biological agent or entity has become paramount to anticipate a possible health threat (epidemic or pandemic), environmental threat or to combat other contextual threats (bioterrorism, chemical and biological weapons, drugs). Consequently, developing a portable cost effective device that could detect and quantify such threats is the research focus of the joint multidisciplinary project between UPMC (Paris 6) laboratories and RWTH university in Aachen, Germany. In the framework of this project, we have studied the multidisciplinary aspects of an electromagnetic microsystem for immunologic detection based on magnetic nanoparticles (MNP) in a microfluidic lab-on-chip (LoC). Because of their extractability and sortability, magnetic nanoparticles are adapted for examination of biological samples, serving as markers for biochemical reactions. So far, the final detection step is mostly achieved by well-known immunochemical or fluorescence-based techniques which are time consuming and have limited sensitivity. Therefore, magnetic immunoassays detecting the analyte by means of magnetic markers constitute a promising alternative. MNP covered with biocompatible surface coating can be specifically bound to analytes, cells, viruses or bacteria. They can also be used for separation and concentration enhancement. The novel frequency mixing magnetic detection method allows quantifying magnetic nanoparticles with a very large dynamic measurement range. In this thesis, emphasis is put on the miniaturized implementation of this detection scheme. Following the development of analytical and multiphysics simulations tools for optimization of both excitation frequencies and detection planar coils, first multilayered printed circuit board prototypes integrating all three different coils along with an adapted microfluidic chip has been designed and realized. These prototypes have been tested and characterized with respect to their performance for limit of detection (LOD) of MNP, linear response and validation of theoretical concepts. Using the frequency mixing magnetic detection technique, a LOD of 15ng/mL for 20 nm core sized MNP has been achieved with a sample volume of 14 μL corresponding to a drop of blood. Preliminary works for biosensing have also been achieved with a state of the art of surface functionalization and a developed proposed biochemical immobilization procedure and preliminary tests of its validation
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Johnson, Chrisopher W. A. "Design and development of a site specific protein patterning technique for use in a microfluidic antibody separation device." Thesis, University of Southampton, 2010. https://eprints.soton.ac.uk/157341/.
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The rapid quantification of the concentration of different immunoglobulins classes from patient serum is required to diagnose patients in the early stages of sepsis. Microfluidic point of care technology can improve diagnostics by decreasing the analysis time, and integrating parallel analysis in a single portable device. The design of a novel method to fabricate surfaces presenting multiple micron scale protein motifs, for integration within a microfluidic channel device, is described in this thesis. Initial research focussed on conjugating protein motifs on silicon <100> substrates in micron and submicron scale patterns. A method involving the UV-initiated conjugation of a heterobifunctional linker, undecylenic acid N-Hydroxysuccinimde ester (UANHS), to a hydrogen terminated silicon surface was investigated. A photolithographic mask and phase mask were used to form micron and submicron UANHS motifs respectively, on silicon. The conjugation of protein with UANHS motifs was investigated to determine how reproducible the patterns were. The conjugation of streptavidin, streptavidin-FITC, NeutrAvidin, single domain protein L and multidomain protein L to silicon surfaces, upon reaction with UANHS, were investigated. Fluorescently labelled probes that associated with the protein motifs were used to confirm successful conjugation of protein to the silicon. Micron scale motifs of streptavidin, streptavidin-FITC, NeutrAvidin and single domain protein L could be formed reproducibly on silicon. Using a phase mask 140 nm motifs of streptavidin-FITC, conjugated to silicon, were achieved. Also an alternative method to pattern multiple proteins onto glass surfaces was investigated. A 500,000 MW dextran was modified to incorporate an aryl azide moiety, which was subsequently immobilised on glass surfaces. A method to synthesise and characterise the aryl azide conjugated dextran was investigated, as well as methods to characterise and improve the reproducibility of the aryl azide conjugated dextran layer immobilised on the glass surface. Two photolithographic masks and glass surfaces with alignment marks were fabricated. The masks were used to form micron scale protein motifs, via a photoinitiated conjugation reaction, on the aryl azide conjugated dextran surface. An in-house alignment system was built and a method to produce adjacent protein motifs was investigated. Two adjacent micron scale patterns of multidomain protein L and protein A were achieved. The surface density of conjugated protein L was investigated and a density of ~1.16x1011 molecules/cm2 was confirmed. This approach offers a method to attach high density micron scale protein motifs, aligned with micron scale resolution, which is vital to the realisation of a microfluidic point of care device.
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Lu, Heng. "Development of droplet-based microfluidic tools for toxicology and cancer research." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCB064.
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Ce projet de thèse portait sur le développement d’outils microfluidiques pour la toxicologie et la recherche contre le cancer. En permettant l’analyse simultanée d’un très grand nombre de réactions biologiques ou chimiques réalisés dans des compartiments indépendants (ie. gouttelettes), la microfluidique de gouttes offre une sensibilité de détection et une précision sans précédent pour l’analyse de molécules biologiques, telles que l’ADN ou les Anticorps, en comparaison des expériences réalisées conventionnellement en tubes ou en microplaques (essais en « bulk » ou volume). Ce format permet également de réaliser des expériences à très haut débit et est particulièrement pertinent pour la toxicologie, où des analyses robustes de l’effet des médicaments sont nécessaires. De même, ces procédures sont également très adaptées à l’analyse de cellules uniques pour le séquençage ADN ou ARN et l’épigénomique. Tout cela fait de la microfluidique en goutte un outil puissant pour la toxicologie et la recherche sur le cancer. En premier temps, une méthode du comptage précise des cellules encapsulée dans des microgouttelettes, nommée « hémocytométrie microfluidique », a été développée. Un nouvel algorithme de comptage a été proposé. Des cellules bactériennes (Escherichia Coli) et des cellules de 2 lignées humaines différentes (HL60 and H1975) ont été testées. Le nombre de chaque type de cellules a été déterminé avec une haute corrélation entre la théorie (basée sur la distribution de Poisson) et les résultats expérimentaux. Avec ces résultats robustes, un protocole de microfluidique en goutte a été mis en place pour interroger la viabilité cellulaire et la prolifération des 2 lignées humaines. Ces résultats sont en concordance avec ceux de la littérature. Pour la toxicologie, 3 différents modèles, y compris des microsomes (extrait de cellules d’insectes infectées par un baculovirus exprimant le cytochrome P450 3A4 humain, CYP3A4), HepG2-CYP3A4 (modifiée génétiquement pour exprimer le gène CYP3A4 humain), et HepaRG, une lignée hépatique, ont été évaluées pour l’activité enzymatique du CYP3A4, une enzyme largement utilisée en routine pour le criblage de médicament candidat. Les microsomes ont permis de développer un essai fluorogénique permettant de mesurer l’inhibition du CYP3A4. Cependant, ni l’utilisation des microsomes ni des cellules HepG2 exprimant CYP3A4 n’a donné de résultats satisfaisants en microgouttelettes. L’utilisation des cellules HepaRG, une lignée cellulaire qui conserve la majorité de l’expression des cytochromes P450 et des récepteurs nucléaires nécessaire à leur expression, a montré des résultats encourageant à la fois sur les tests de mesure de l’activité enzymatique et d’analyse de l’induction du CYP3A4. Pour la recherche sur le cancer, 4 essais originaux de PCR digitale en gouttes ont été mis en place pour la détection et la quantification de mutations (NRAS, DNMT3A, SF3B1 and JAK2) importante pour les syndromes myélodysplasiques, un groupe hétérogène de maladies touchant les cellules souches hématopoïétiques caractérisées par une hématopoïèse inefficace et des cytopénies périphériques. Finalement, un essai de PCR sur cellule unique encapsulées au sein de billes agarose a été proposéThis thesis project consists in developing droplet-based microfluidic tools for toxicology and cancer research. Owing to its large numbers of discretized volumes, sensitivity of detection of droplet-based microfluidics for biological molecules such as DNA and antibody is much higher than bulk assays. This high throughput format is particularly suitable for experiments where a robust dose-response curve is needed, as well as for single cell analysis with applications in genomic or sequencing and epigenetics. All above makes droplet-based microfluidics a powerful tool for toxicology and cancer research. In a first part of the work, an accurate cell counting method, named “microfluidics hemocytometry”, has been developed. A new counting algorithm was proposed to count the cells within each droplet. Escherichia Coli and two different human cell lines (HL60 and H1975) were used to validate our strategy. The number of each type of cells in droplets was determined with a high consistency between theory (Poisson distribution) and experimental results. With these robust results, a droplet-based microfluidic protocol has then been established to inquiry both cell viability and proliferation for the two human cell lines. The results are in good agreement with the one of the literature. For the toxicology, 3 different biological models, including microsomes (extracted from baculovirus-infected insect cell expressing human CYP3A4), HepG2-CYP3A4 (genetically modified to express the human CYP3A4 gene) and HepaRG liver cells lines were evaluated for enzymatic activity of cytochromes P450 (CYP3A4), a routinely used enzyme for drug candidate screening. Microsome-based assays were used to validate a fluorogenic inhibition assay. However neither microsome-based assay nor the assay using CYP3A4 expressing HepG2 gave satisfying results in droplet-based format. However, HepaRG cells, a hepatic function-conserved cell line with most cytochrome and related nuclear receptors, demonstrated high relevance both for enzymatic activity testing and CYP3A4 expression induction study. For cancer research, 4 different picoliter droplet-based PCR assays were developed for the detection and quantification of mutations (NRAS, DNMT3A, SF3B1 and JAK2) present in Myelodysplastic syndromes, a heterogeneous group of clonal bone marrow hematopoietic stem cell disorders characterized by ineffective hematopoiesis and peripheral cytopenias. Furthermore, a single cell multistep PCR assay using encapsulation of target DNA in agarose droplets was proposed
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Nikcevic, Irena. "Development of techniques and materials for microfluidic devices." Cincinnati, Ohio : University of Cincinnati, 2008. http://rave.ohiolink.edu/etdc/view.cgi?acc_num=ucin1212155007.
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Rajah, Luke. "Biophysical and microfluidic techniques for investigating protein aggregation." Thesis, University of Cambridge, 2013. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.608030.
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NIKCEVIC, IRENA. "Development of techniques and materials for microfluidic devices." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1212155007.
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Puccetti, Giacomo <1988>. "Optical Techniques for Experimental Tests in Microfluidics." Doctoral thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amsdottorato.unibo.it/7534/.
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This PhD dissertation deals with the use of optical, non-invasive measurement techniques for the investigation of single and two-phase flows in microchannels. Different experimental techniques are presented and the achieved results are critically discussed.
Firstly, the inverse use of the micro Particle Image Velocimetry technique for the detection of the real shape of the inner cross-section of an optical accessible microchannel is shown by putting in evidence the capability of this technique to individuate the presence of singularities along the wetted perimeter of the microchannel. Then, the experimental measurement of the local fluid temperature using non-encapsulated Thermochromic Liquid Crystal particles is discussed. A deep analysis of the stability of the color of these particles when exposed to different levels of shear stress has been conducted by demonstrating that these particles can be used for simultaneous measurements of velocity and temperature in water laminar flows characterized by low Reynolds numbers (Re < 10). A preliminary experiment where the TLC thermography is coupled to the APTV method for the simultaneous measurement of the three-dimensional velocity and temperature distribution in a microchannel is shown. Finally, an experimental analysis of the different flow patterns observed for an adiabatic air-water mixture generated by means of a micro T-junction is discussed. The main air-water mixture features have been deeply observed in 195 different experimental conditions in which values of superficial velocity ranging between 0.01 m/s and 0.15 m/s for both the inlet flows (air and water) are imposed. The flow patterns of the air-water mixture are strongly influenced by the value of the water superficial velocity; on the contrary, the air superficial velocity plays a secondary role for the determination of the characteristics of the bubbles (i.e. length).
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Chen, Chih-chen. "Microfluidic elastomeric platforms for probing single cells /." Thesis, Connect to this title online; UW restricted, 2006. http://hdl.handle.net/1773/8029.
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Helton, Kristen Lloyd. "Preconditioning saliva to measure small analytes in a microfluidic biosensor /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/8078.
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Park, Jaesung. "Study of microfluidic measurement techniques using novel optical imaging diagnostics." Diss., Texas A&M University, 2005. http://hdl.handle.net/1969.1/4953.
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Novel microscale velocity and temperature measurement techniques were studied based on confocal laser scanning microscopy (CLSM) and optical serial sectioning microscopy (OSSM). Two microscopic measurement systems were developed, 1) a CLSM micro particle image velocimetry (PIV) system with a dual Nipkow disk confocal unit (CSU-10), a CW argon-ion laser and an upright microscope, and 2) an OSSM micro- particle tracking velocimetry (PTV) system with an epi-fluorescence microscope and a non-designed specimen to make a three-dimensional (3-D) diffraction particle image. The CLSM micro-PIV system shows a unique optical slicing capability allowing true depth-wise resolved vector field mapping. A comparative study is presented between the CLSM micro-PIV and a conventional epi-fluorescence micro-PIV. Both have been applied to the creeping Poiseuille flows in two different microtubes of 99-õm (Re = 0.00275) and 516-õm ID diameters (Re = 0.021). The CLSM micro-PIV consistently shows significantly improved particle image contrasts, the definition of "optical slicing" and measured flow vector fields more accurately agreeing with predictions based on the Poiseuille flow fields, compared to the conventional micro-PIV. The OSSM micro-PTV technique is applied for a 3-D vector field mapping in a microscopic flow and a Brownian motion tracking of nanoparticles. This technique modifies OSSM system for a micro-fluidic experiment, and the imaging system captures a diffracted particle image having numerous circular fringes instead of an in-focus particle image. The 3-D particle tracking is based on a correlation between the 3-D diffraction pattern of a particle and the defocus distance from a focal plane. A computational program is invented for the OSSM micro-PTV, and provides a 3-D velocity vector field with a spatial resolution of 5.16 õm. In addition, a concept of nonintrusive thermometry is presented based on the correlation of the Brownian motion of suspended nanoparticles with the surrounding fluid temperature. Detection of fully three-dimensional Brownian motion is possible by the use of the OSSM, and the measured value of mean square displacement (MSD) is compared fairly well with Einstein's predictions.
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Sudarsan, Arjun Penubolu. "Multivortex micromixing: novel techniques using Dean flows for passive microfluidic mixing." Texas A&M University, 2006. http://hdl.handle.net/1969.1/4686.
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Mixing of fluids at the microscale poses a variety of challenges, many of which
arise from the fact that molecular diffusion is the dominant transport mechanism in the
laminar flow regime. The unfavorable combination of low Reynolds numbers and high
Péclet numbers implies that cumbersomely long microchannels are required to achieve
efficient levels of micromixing. Although considerable progress has been made toward
overcoming these limitations (e.g., exploiting chaotic effects), many techniques employ
intricate 3-D flow networks whose complexity can make them difficult to build and
operate. In this research, we show that enhanced micromixing can be achieved using
topologically simple and easily fabricated planar 2-D microchannels by simply
introducing curvature and changes in width in a prescribed manner. This is
accomplished by harnessing a synergistic combination of (i) Dean vortices that arise in
the vertical plane of curved channels as a consequence of an interplay between inertial,
centrifugal, and viscous effects, and (ii) expansion vortices that arise in the horizontal
plane due to an abrupt increase in a conduitâÂÂs cross-sectional area. We characterize these effects using top-view imaging of aqueous streams labeled with tracer dyes and
confocal microscopy of aqueous fluorescent dye streams, and by observing binding
interactions between an intercalating dye and double-stranded DNA. These mixing
approaches are versatile, scalable, and can be straightforwardly integrated as generic
components in a variety of lab-on-a-chip systems.
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Du, Ke. "Noval nanoindentation-based techniques of MEMS and microfluidics applications." [Tampa, Fla] : University of South Florida, 2008. http://purl.fcla.edu/usf/dc/et/SFE0002778.
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Du, Ke. "Novel Nanoindentation-Based Techniques for MEMS and Microfluidics Applications." Scholar Commons, 2008. https://scholarcommons.usf.edu/etd/220.
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In this thesis, the mechanical characterization of thin films, bulk materials, compliant MEMS and Microfluidics has been discussed. In chapter1 and chapter 2, the Indentation Size Effect (ISE) has been studied for single crystal aluminum and the substrate effect has also been studied for 200 nm gold film on mica substrate and 50 nm gold film on (100) silicon wafer substrate. The mechanical characterization of super hard SiC films (prepared by CVD) has also been discussed.
In chapter 3, the actuation of compliant MEMS devices with a nanoindentation apparatus has been investigated. Friction forces become important at the device level, and the conical tip always makes a crack at the edge of the sliders, thus the slider design needs to be optimized to account for the probe geometry.
In chapter 4, the measurement of electrowetting has been outlined. The "airscratch" mode was used to capture the lateral force and normal force during an electrowetting test. With the appearance of surface delamination on the solid surface, the unexpected normal forces can been measured.
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Edel, Joshua B. "Development of single molecule and particle detection techniques for microfluidic analysis." Thesis, Imperial College London, 2004. http://hdl.handle.net/10044/1/11215.
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Ogilvie, Iain R. G. "Novel fabrication techniques for microfluidic based in-situ oceanographic nutrient sensors." Thesis, University of Southampton, 2012. https://eprints.soton.ac.uk/342947/.
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This work presents an investigation into the production of components for in-situ oceanographic nutrient sensors. These devices are based on a micro fluidic chip platform, taking the lab-on-a-chip (LOC) system concept out of the laboratory and into a real world environment. The systems are designed to provide data on nutrient concentrations in the ocean and as such are built from robust low cost materials designed for deployments from 24 hours to 3 months. This report focuses on the challenges faced in designing a micro fluidic system for these harsh deployment situations including a study of the relevant literature to indicate short falls in current technologies. The aim of this work was to develop the next generation of micro fluidic chip based nutrient sensors. A novel solvent vapour bonding technique has been developed for the production of polymer based micro fluidic chips which produces robust chips while simultaneously reducing the surface roughness of the substrates during bonding. This has allowed micromilling of polymer substrates to quickly and easily develop new chip designs with optical quality features. The surface reduction technology has enabled development of a method to integrate absorbance cells into tinted PMMA devices which is also discussed. Integration of polymer membranes to produce valve and pump structures is discussed and a novel bonding technique for chemically robust Viton R membranes is demonstrated. The final chapter includes a discussion on system topologies, concentrating on the need for high resolution sampling and the implications on system design that arise. A novel multiplexed stop ow system is demonstrated. Questions about the role of traditional micro fluidic components, such as mixers, in high-throughput low temporal response system designs are discussed and a micro fluidic mixer suitable for some of these systems demonstrated.
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Stapountzis, Margarita Antonia. "Development of fluorescence lifetime measurement techniques for use in microfluidic channels." Thesis, Imperial College London, 2013. http://hdl.handle.net/10044/1/14619.
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Fluorescence lifetime measurements are a powerful tool in biomedical research and advances in detection technology make them ideally suited for the study of biomolecular interactions. Time-resolved techniques, compared to more conventional methods, provide improved precision and contrast in the monitoring of complex biological processes. Fluorescence lifetimes are extracted by using time-correlated single-photon counting, which offers single photon sensitivity, high temporal resolution and excellent signal to noise ratio. Furthermore, combining this technique with microfluidics offers unprecedented advantages. For example, in analytical applications, apart from the high sensitivity required, the study of analytes often demands low sample consumption and short mixing times to allow for the monitoring of quick reactions. These parameters can nicely be achieved with the use of microfluidics. Hydrodynamic focusing within 3-inlet 1-outlet continuous flow microfluidic devices can be used as a molecular confinement mechanism to improve the detection efficiency as well as a means to enhance mixing within microchannels for the study of fast reaction kinetics. In this work, a powerful combination of confocal microscopy and microfluidics was used to perform fluorescence lifetime measurements on freely diffusing and freely flowing molecules. For this purpose, a home-built scanning confocal system was developed to ensure sufficient reduction in background levels, enabling the detection of fluorescence signal that arises from single molecules. Fluorescence lifetime imaging along with a maximum likelihood estimator adapted from single molecule studies was performed to visualise hydrodynamic focusing and characterise mixing within microfluidic devices. Time-resolved methods were also employed to detect single molecules freely flowing within microchannels. A novel fluorescence lifetime approach was developed to perform Förster resonance energy transfer measurements on freely diffusing molecules and subsequently applied for the study of streptavidin-biotin binding and protein conformational changes upon unfolding.
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Corbin, Inge. "Analysis of Improvised Explosives by Electrospray Ionization - Mass Spectrometry and Microfluidic Techniques." FIU Digital Commons, 2016. http://digitalcommons.fiu.edu/etd/2551.
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Improvised explosives may be based on smokeless gunpowder, fertilizers, or inorganic oxidizers such as nitrate (NO3-), chlorate (ClO3-), and perchlorate (ClO4-) salts.
Identification is a priority for the military and law enforcement but due to their varying physical properties and complexity, identification can be challenging. Consequently, three methods have been developed to aid in presumptive and confirmatory detection.
Smokeless powder contains plasticizers, stabilizers, dyes, opacifiers, flash suppressants, and other compounds. Identification of these additives can narrow down or identify the brands of smokeless powder used in a device. Fourteen organic smokeless powder components were identified by capillary electrochromatography (CEC) using a hexyl acrylate monolithic stationary phase coupled to UV detection and time-of-flight mass spectrometry (TOF-MS). The CEC-UV method efficiently detects all 14 organic components, while TOF-MS provides sensitivity and selectivity. A mixed smokeless powder component standard was analyzed and the composition of the additive package in commercial smokeless powders determined. Detection limits ranged from 1.0 – 3.2 μg/ml and analysis time was 18 minutes.
Second, a procedure for the detection of urea nitrate (UN) and ammonium nitrate (AN) by infusion electrospray ionization - mass spectrometry (ESI-MS/MS) was developed. Solubility tests were performed to find a solvent for both UN and AN that did not cause UN to dissociate. Two adduct ions were detected for each explosive: for AN, m/z 178 [2AN+NH4]+ and m/z 258 [3AN+NH4]+ ions, and for UN m/z 185 [UN+NO3]− and m/z 248 [UN+HNO3+NO3]−. Specificity of the analysis was examined by mixing the explosives with various salts and interferents. Gas-phase adduct ions were useful in distinguishing between ion pairs and mixed salts.
Finally, a paper microfluidic device (PMD) was developed as a presumptive test using colorimetric reagents for the detection of ions associated with improvised explosives. The device was configured to test for nitrate (NO3-), nitrite (NO2-), chlorate (ClO3-), perchlorate (ClO4-), and urea nitrate (UN). Proof of concept was performed using extracts of soil containing inorganic oxidizers.
The development of these analytical methods allows the detection of smokeless powder components, fertilizers, and oxidizers and expands the suite of analytical methods available for the analysis of improvised explosives.
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Dey, Abhishek. "Frequency Tunable Antennas and Surface Microwave Imaging System Using Microfluidic Reconfiguration Techniques." Scholar Commons, 2016. http://scholarcommons.usf.edu/etd/6491.
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Reconfigurable radio frequency (RF) devices are attractive for miniaturization of wireless components and systems by handling functionality of multiple distinct devices. Existing reconfiguration techniques rely on device loadings with semiconductor diodes, ferrite/ferroelectric materials, and microelectromechanical system (MEMS) switches and capacitors. However, it is well-recognized that these techniques cannot fully address important system metrics such as high efficiency, wide frequency tuning range, high power handling capability and cost. Therefore, novel alternative techniques are highly desirable to advance the state of the art in reconfigurable RF devices. The aim of this dissertation is to investigate the novel concept of microfluidically loaded reconfigurability within the context of RF antennas and imaging systems. The proposed devices operate based on continuously movable microfluidic loads consisting of metal (liquid/solid) and dielectric solutions. Microfluidics and microfabrication techniques are utilized with flexible/rigid multilayered substrates to maximize the reconfigurable loading effect on the devices and enable highly reconfigurable antennas and imaging array realizations. Specifically, a wideband frequency tunable monopole antenna is introduced by utilizing continuously movable liquid metal within the microfluidic channel as a length varying conductor. By resorting to ultra-thin channel walls, the liquid metal volume overlapping with the microstrip line feed is utilized as a non-radiating capacitive excitation point to achieve the realized 4:1 (1.29GHz – 5.17GHz) frequency tuning range. Subsequently, an alternative design that replaces liquid metal volume with a microfluidically movable metallized plate is introduced. This novel liquid-metal-free implementation alleviates the liquid metal associated drawbacks of reliability, long-term device operation, and efficiency. The antenna is shown to provide 2:1 (1.6GHz – 3.5GHz) frequency tuning range with > 87 % radiation efficient. Due to the high radiation efficiency, the antenna is also capable of handling 15 W of RF power which is 10 W more than its liquid metal counterpart. This metallized plate approach is also suitable for reconfiguration of miniature antennas, and this is demonstrated with the design/implementation of a microfluidically reconfigurable top loaded monopole antenna. It is also suitable for reconfiguration of other structures such as textile antennas – and this is demonstrated with a 0.8GHz to 1.4GHz frequency reconfigurable textile antenna realization. The last section of the dissertation introduces a novel surface imaging array realization by utilizing the microfluidically reconfigurable metallized plate as an RF read-out circuit component. Specifically, a 24 element imaging array is designed and validated to operate within 6 – 12 GHz band with subwavelength resonators to demonstrate the possibility of constructing low-cost high-resolution microwave surface imaging arrays by utilizing the microfluidics based reconfiguration techniques. The presented work emphasizes system level implementation of the proposed devices by integrating them with micropump units, controller boards, and investigating their reliability performances under higher power RF excitations.
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Foley, Jennifer Olivia. "Design and development of surface plasmon resonance imaging microfluidic assays /." Thesis, Connect to this title online; UW restricted, 2007. http://hdl.handle.net/1773/7982.
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Kamholz, Andrew Evan. "Quantitative analysis of diffusion and chemical reaction in pressure-driven microfluidic channels /." Thesis, Connect to this title online; UW restricted, 2001. http://hdl.handle.net/1773/8020.
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Jacksén, Johan. "Improved techniques for CE and MALDI-MS including microfluidic hyphenations foranalysis of biomolecules." Doctoral thesis, KTH, Analytisk kemi, 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-27342.
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In this thesis, improved techniques for biomolecule analysis using capillary electrophoresis (CE) and matrix-assisted laser desorption/ionization-mass spectrometry (MALDI-MS) and hyphenations between those have been presented.A pre-concentration method which is possible to apply in both techniques, has also been investigated. In this work the off-line MS mode has been used either in the form of fractionation (Paper I) or by incorporating the MALDI target in the CE separation system (Paper II).In Paper I, a protocol for CE-MALDI analysis of cyanogen bromide digested bacteriorhodopsin (BR) peptides as model integral membrane protein peptides were established. Also, an improved protocol for partially automated manufacturing of a concentration MALDI-target plate is presented. The design of the targets was suitable for the fractions from the CE. A novel technique for the integration of CE to MALDI-MS using a closed-open-closed system is presented in Paper II, where the open part is a micro canal functioning as a MALDI target window. A protein separation was obtained and detected with MALDI-MS analysis in the micro canal. A method has been developed for detection of monosaccharides originating from hydrolysis of a single wood fiber performed in a micro channel, with an incorporated electromigration pre-concentration step preceding CE analysis in Paper III. The pre-concentration showed to be highly complex due to the fact that several parameters are included that affecting each other. In Paper IV a protocol using enzymatic digestion, MALDI-TOF-MS and CE with laser induced fluorescence (LIF) detection for the investigation of the degree of substitution of fluorescein isothiocyanate (FITC) to bovine serum albumin (BSA), as a contact allergen model system for protein-hapten binding in the skin, is presented. The intention of a further CE-MALDI hyphenation has been considered during the work. In Paper V 2,6-dihydroxyacetophenone (DHAP) was investigated, showing promising MALDI-MS matrix properties for hydrophobic proteins and peptides. 2,5-dihydroxybenzoic acid (DHB) was undoubtedly the better matrix for the hydrophilic proteins, but its performance for the larger and hydrophobic peptides was not optimal. Consequently, DHAP can be used as a compliment matrix for improved analysis of hydrophobic analytes.QC 20101214
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Viberg, Pernilla. "Development of non-adherent single cell culturing and analysis techniques on microfluidic devices." Diss., Manhattan, Kan. : Kansas State University, 2009. http://hdl.handle.net/2097/1441.
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Reuter, Marcel. "Bacterial protein complexes studied by single-molecule imaging and single-cell micromanipulation techniques in microfluidic devices." Thesis, University of Edinburgh, 2010. http://hdl.handle.net/1842/6192.
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Biological systems of bacteria were investigated at the single-cell and single-molecule level. Additionally, aspects of the techniques employed were studied. A unifying theme in each project is the reliance on optical imaging techniques coupled to microfluidic devices. Hypo-osmotic shock experiments with an Escherichia coli mechanosensitive channel deletion mutant were carried out at the single-cell level. E. coli MJF465 cells in which the three major mechanosensitive channel genes are deleted (∆mscL, ∆mscS, ∆mscK) show only 10% cell viability upon hypo-osmotic shock (from LB + 0.5 M NaCl into distilled water), compared to 90% viability of the wild-type strain. Bacterial cells were trapped with optical tweezers in microfluidic devices, enabling the first direct observation of single-cell behaviour upon hypo-osmotic shock. Phase-contrast microscopy revealed intra-population diversity in the cells response: Different features of lysis included cells bursting rapidly and leakage of ribosomes, DNA and protein from the cytoplasm. Fluorescence microscopy of hypo-osmotically-shocked GFP-expressing MJF465 cells showed either bursting of cells, which was a rare event, or fast leakage of GFP, indicating cell membrane ruptures. Data were analysed in terms of their kinetic behaviour and showed that lysis occurs on a timescale of milliseconds to seconds. The implications of these findings for the bacterial cell wall and cell membranes are discussed. Enzymes involved in homologous recombination and repair of double-stranded DNA (dsDNA) breaks are essential for maintaining genomic integrity in both eukaryotes and prokaryotes. RecBCD of E. coli and AddAB, found widely in bacteria, are involved in these processes, carrying out the same function. Both enzymes were studied kinetically with single-molecule total internal reflection fluorescence microscopy (TIRFM). Surface-tethered, hydrodynamically stretched lambda-DNA molecules, stained with YOYO-1, were imaged with TIRFM in a microfluidic flowcell. The RecBCD enzyme is a well characterised DNA helicase and was introduced to this system for method validation purposes. The AddAB enzyme of Bacteroides fragilis was then characterised as a helicase acting on lambda-DNA. It was found that AddAB helicase unwinds dsDNA with high processivity of on average 14,000 bp and up to 40,000 bp for individual enzyme complexes at an ATP-dependent rate ranging from 50-250 bp s−1 (for Mg2+-ATP concentrations larger or equal than 0.1 mM). This activity was detected by DNA binding dye (YOYO-1) displacement from the dsDNA and studied for different Mg2+-ATP concentrations, flow (shear) rates and different YOYO-1 staining ratios of DNA. Aspects of this last experimental setup were investigated. A kinetic analysis of intercalation of YOYO-1 into lambda-DNA is presented, occurring on a timescale of minutes. Different flow rates and staining ratios that influence the apparent (stretched) DNA molecule length were also examined. Several image analysis techniques were employed to enhance the data quality in images showing stretched lambda-DNA molecules. The Singular Value Decomposition was found to be the most effective technique which strongly reduces the noise in the obtained kymograph images.
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Wang, Chao. "Microfluidics for particle manipulation : new simulation techniques for novel devices and applications." Thesis, University of Oxford, 2013. http://ora.ox.ac.uk/objects/uuid:8125980e-0603-4425-b0fa-89a4fdfdf464.
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This thesis focuses on fundamental aspects of microfluidic systems and applies relevant findings to innovative designs for advanced particle manipulation applications. Computational Fluid Dynamics (CFD) is adopted for fluid modeling, based on the Finite Volume method. The accuracy of the solutions obtained is confirmed by grid sensitivity analysis and by comparisons with experimental work. Curved microchannel features and the induced Dean flow are studied through a parametric space exploration and simulations. The Lagrange-Euler coupling method – Surface Marker Point methodology – is applied to simulate large-size particles (of comparable size to the channel). Through this simulation approach, all the forces on such particles are directly derived through solving the governing equations and the influence of these particles on the flow is considered in a fully coupled manner. A new approach – the Frozen Flow & Flow Correction Coefficient method – is developed, making trans-relaxation-time simulations possible and improving computational efficiency significantly, for 3D simulations of arbitrary shape and size microparticles in complicated microfluidic channels. Detailed comparisons between simulation results and experiments involving particle sedimentation and particle equilibrium position have been conducted for methodology validation. Mechanisms of hydrodynamic particle manipulation are then studied, including hydrodynamic focusing and separation. It is found that the Tubular Pinch effect, Dean flow and the Radial Pressure Gradient effect interact to yield two distinct particle separation mechanisms. For advanced applications, particle focusing, non-magnetic and magnetic separation for neutrally buoyant particles are proposed, based on newly gained insight on the above-mentioned mechanisms. Appropriate channel designs have been proposed both for particle focusing and size-based particle separation, while the vertical-magnetic-Dean separation scheme is highlighted for magnetic separation. Finally, a new integrated system is proposed, that combines the above novel designs into a device-like ensemble. It promises to offer functionality for biomaterial separation and detection, including different types of cells, antigens and biomarkers.
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Kong, Cher Rong Matthew. "Contactless liquid flow control for miniaturised analytical techniques on continually rotating centrifugal microfluidic platforms." Thesis, McGill University, 2013. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=117150.
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In an industrial society it is critical that techniques be developed for the measurement of chemical species in the environment, in humans and as both intended and unintended products of manufacturing. Initially, these techniques were developed around sophisticated instruments and often involved complex procedures. It is obviously advantageous if the cost of analyses can be reduced and the experimental procedures simplified, while still maintaining the quality of the data collected. Furthermore, it is often desirable to have measurements performed rapidly, with on-site measurement sometimes deemed useful or even essential. All of these desirable outcomes may, in some cases, be obtained by miniaturisation. The interest in miniaturisation has led to rapid growth of the field of microfluidics, an area of study which involves using small volumes of liquids, often with detection systems specifically tailored to these reduced volumes. Microfluidic systems must have some way of moving liquids through various stages of chemical or physical processes. One particularly interesting pumping method involves the use of centrifugal force, which eliminates the need for pumps and minimises connections to the platform on which the analysis is done. Up to this point, centrifugal systems have generally been constrained to a limited number of sequential analytical steps as liquid could only flow in the direction demanded by the applied centrifugal force.In this thesis, a variety of liquid manipulation techniques on centrifugal microfluidic platforms were developed and characterised. These techniques were used to miniaturise standard classical analytical methods and implement them on centrifugal microfluidic platforms with the goal of monitoring environmentally important compounds such as aqueous sulfide. A two-phase liquid displacement pumping technique and a pneumatic-centrifugal pumping technique are demonstrated and presented. The developed pneumatic-centrifugal system was used to significantly increase the toolbox of capabilities for centrifugal microfluidic platforms, simultaneously enabling critical microfluidic operations such as valveless liquid transfer, metering, liquid flow switching, agitative micromixing, and liquid recirculation. This technique is based on contactless implementation of pneumatic pressure using compressed air on a continually rotating centrifugal microfluidic platform, thereby enabling complete liquid flow control by combining the effects of pneumatic pressure and centrifugal force.This new type of pneumatically enhanced centrifugal microfluidic platform greatly simplifies the fabrication process by minimising valving requirements, as well as improving efficiency by performing analyses in a highly automated manner. The pneumatic approach was applied to an on-disk calibration and spectrophotometric measurement using the method of standard additions. Similarly, another pneumatically enhanced platform was developed for performing liquid-liquid extractions between an aqueous phase and an organic phase, demonstrating that these centrifugal platforms are not only capable of performing complex multi-step reactions, but also multi-cycle reactions and processes. Finally, an application-specific pneumatically enhanced centrifugal platform was developed for the spectrophotometric determination of aqueous hydrogen sulfide.All of the developed analytical methods only required small sample and reagent volumes, are highly automated and convenient, and have the potential to be performed in a field environment without the need for highly trained personnel.Dans notre société industrielle, la conception de techniques pour la quantification d'espèces chimiques dans l'environnement, les humains et les dérivés de la production manufacturière est primordiale. Au départ, ces techniques avaient été élaborées à partir d'instruments sophistiqués et se basaient sur des procédures complexes. Il serait donc avantageux de pouvoir réduire les coûts d'analyse et simplifier les procédures expérimentales, tout en maintenant un niveau élevé de la qualité des données recueillies. De plus, il est souvent souhaitable de pouvoir effectuer ces mesures rapidement, et si possible sur le site où l'échantillon à analyser est recueilli. Toutes ces caractéristiques bénéfiques des méthodes analytiques peuvent être obtenues, dans certains cas, à travers la miniaturisation. L'intérêt pour la miniaturisation a mené à une croissance rapide des systèmes microfluidiques, un domaine d'études qui se concentre sur l'utilisation de petits volumes de liquide et des systèmes de détection spécialement adaptés à ces volumes réduits. Tout système microfluidique doit intégrer une méthode de transfert des liquides à travers différentes étapes de traitements chimiques ou physiques. Une méthode de pompage particulièrement intéressante utilise la force centrifuge, ce qui permet d'éliminer l'utilisation de pompes ou connections externes au système où s'effectue l'analyse chimique. Jusqu'à présent, les systèmes employant la force centrifuge ont été limités par le nombre d'étapes analytiques consécutives, le liquide ne pouvant se déplacer que dans une seule direction définie par la force centrifuge appliquée.Pour cette thèse, plusieurs techniques de manipulation des liquides sur un système microfluidique à base de force centrifuge ont été dévelopées et caractérisées. Ces techniques ont été utilisées pour miniaturiser les méthodes analytiques classiques pour ensuite les intégrer à des plateformes microfluidiques à base de force centrifuge, l'objectif final étant la surveillance d'espèces chimiques dans l'environnement. Une technique de pompage par déplacement de deux phases liquides et une technique de pompage pneumatique à base de force centrifuge sont démontrées. La technique pneumatique à base de force centrifuge qui a été développée augmente de façon significative les capacités de la boîte à outils des systèmes microfluidiques à base de force centrifuge. Ce nouveau système permet d'effectuer simultanément des opérations essentielles dans les systèmes microfluidiques telles que le transfert de liquides sans valves, les dosages, la commutation du débit des liquides, les micromélanges par agitation ainsi que la recirculation des liquides. Cette technique se base sur l'application sans contact d'une pression pneumatique en utilisant de l'air comprimé sur un système microfluidique à base de force centrifuge en rotation constante. Ceci permet un contrôle complet du débit des liquides en combinant les effets de la pression pneumatique et de la force centrifuge. Le processus de fabrication de ce nouveau système est grandement simplifié par l'ajout du système pneumatique car cela diminue le nombre de valves à intégrer dans le système. De plus, son efficacité est accrue grâce à la possibilité d'effectuer des analyses de façon automatisée. Cette approche pneumatique a été appliquée à des mesures spectrophotométriques par la méthode des additions connues effectuées directement sur le disque. Dans le même ordre d'idées, un autre système employant la fonction pneumatique a été développé pour effectuer des extractions liquide-liquide entre une phase liquide et une phase organique. Ceci a démontré que la plateforme centrifuge est capable non seulement d'effectuer des réactions chimiques complexes en plusieurs étapes, mais aussi de répéter les cycles de réactions et autres processus.
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Rezaei, Nejad Hojatollah. "Development of techniques for rapid isolation and separation of particles in digital microfluidics." Thesis, University of British Columbia, 2016. http://hdl.handle.net/2429/57956.
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Digital microfluidics (DMF) has emerged as a powerful platform for both research and development in life science studies. The platform functions based on handling small volumes of samples and reagents in the form of discrete droplets using the well-established electrowetting on dielectric (EWOD) method. Based on EWOD, different techniques (operators) have been developed to accurately manipulate, dispense, split and merge droplets of different volumes. Despite the advances made in the DMF technology especially in the use of EWOD in scaling down laboratory procedures, there is lack of understanding and hence development of techniques for particle/cell manipulation and isolation on DMF (as compared to the alternative platform called continuous microfluidics). This has hindered the capability of DMF in full-scale miniaturization of laboratory procedures requiring particle/cell isolation at any of their steps. This research focuses on addressing this problem and developing reliable techniques to manipulate, concentrate and isolate different types of particles/cells. The techniques presented here are particularly developed to limit the use of external devices and also cover a wide range of particles and cells with different physical properties (including size, density, material and electromagnetic properties). They include magnetic collection, hydrodynamic focusing, dielectrophoresis positioning of the particles. The magnetic collection method, a rather simple but effective and widely used in biochemistry, is implemented on DMF for capturing target analytes. The hydrodynamic focusing method, functioning based on the density and size of the particles, were developed and integrated into DMF (for the first time) using especial electrode geometry facilitating the rotation of the droplet. The dielectrophoresis–based particle manipulation is optimized to achieve high resolution and controllability in particle patterning on DMF. The applicability of each of these techniques are demonstrated for different biological and physical applications including on-chip DNA purification (using the magnetic collection technique), ultra-low DNA concentration (using the hydrodynamic focusing technique for achieving desired concentrations of particles), and cell and particle patterning and cell culturing on a DMF platform (using the dielectrophoresis positioning technique). The diversity and flexibility of these techniques will enable the use of DMF devices for especially point-of-care applications.Applied Science, Faculty of
Engineering, School of (Okanagan)
Graduate
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Carr, Simon David. "Assessing the effects of radiotherapy on head and neck squamous cell carcinoma using microfluidic techniques." Thesis, University of Hull, 2013. http://hydra.hull.ac.uk/resources/hull:8396.
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Objective The aim of this study was to investigate how HNSCC tissue biopsies maintained in a pseudo in vivo environment within a bespoke microfluidic device, respond to radiation treatment. Materials and Methods 35 patients with HNSCC were recruited; in addition liver tissue from 5 Wistar rats was used. A glass microfluidic device was used to maintain the tissue biopsy samples in a viable state. Rat liver was used to optimise the methodology. HNSCC was obtained from patients with T1-T3 laryngeal or oropharyngeal SCC; N1-N2 metastatic cervical lymph nodes were also obtained. Irradiation consisted of single doses of between 2 Gy and 40 Gy and a fractionated course of 5x2 Gy. Cell death was assessed in the tissue effluent using the soluble markers LDH and cytochrome c, and in the tissue by immunohistochemical detection of cleaved cytokeratin18 (M30 antibody). Radiation-induced DNA strand breaks were detected using the TUNEL assay. Results A significant surge in LDH release was demonstrated in the rat liver after a single dose of 20 Gy; in HNSCC it was seen after 40 Gy, compared to the control. There was no significant difference in cytochrome c release after 5 Gy or 10 Gy. M30 demonstrated a dose-dependent increase in apoptotic index for a given increase in single dose radiation. There was a significant increase in apoptotic index between the non-irradiated HNSCC tissue and irradiated tissue and between the tissue irradiated with 1x2 Gy and 5x2 Gy. As with the apoptotic index, there was a significant increase in radiation-induced DNA breaks between the non-irradiated and the irradiated tissue and between the tissue irradiated with 1x2 Gy and 5x2 Gy. Conclusion This microfluidic technique can be used to study the effects of radiation on HNSCC tissue. The device was capable of maintaining the HNSCC in a viable state, without it undergoing significant apoptosis or DNA damage and can be used to demonstrate the relationship between radiotherapy dose and radiation-induced cell death using tissue-based cell death markers. This study is a significant step towards achieving the ultimate goal of developing this device as a tool, capable of predicting a patient’s response to radiotherapy prior to the commencement of treatment.
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El-Sabbahy, H. "Development of preparative microfluidic techniques for lysis of microbial cells and affinity purification of proteins." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1419100/.
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In order to fully realise the benefits of microscale mammalian cell culture and microbial fermentation systems, a device capable of online sample preparation to enable further investigation of product quality is a key requirement. The aim of this work is to move toward such a device by designing and characterising a microfluidic lysis device and microaffinity chromatography device that are compatible with each other. The resulting microfluidic lysis device is useful for preparatory lysis of microbial cells. It works by mixing a lysis reagent (BugBuster MastermixTM), with microbial culture, using a T-Piece connection. Lysis takes place in a 700µm internal diameter fused silica capillary. The device was able to successfully lyse microbial cells with similar active Glutathione S Transferase release to sonication. The operating flowrate range of the device was 3.207µL min-1 to 6.414 µL min-1 and the device volume was 30µL - 60µL. The microaffinity chromatography column performed well in studies with pure Glutathione S Transferase. It showed good loading and elution behaviour. The breakthrough and elution curves, and quantity of protein eluted per unit bed volume, were similar to lab scale. The difference being as a result of experimental error. The column also performed well with a 100% clarified Escherichia coli lysate containing recombinant Glutathione S Transferase from Schistosoma japonicum. The eluate had a purity of 55% and concentration of 2.24 mg/ml. The column was fabricated from inexpensive fused silica capillary. It had an internal diameter of 700µm, a length of 5cm (the same length as a typical lab scale Glutathione Affinity column), and a bed volume of approximately 19µL. The operating flowrate range for the column was the same as the microlysis device.
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Herbst, Maria [Verfasser], and Stephan [Akademischer Betreuer] Förster. "Microfluidic and X-ray techniques for investigations of nanoparticle nucleation and growth / Maria Herbst ; Betreuer: Stephan Förster." Bayreuth : Universität Bayreuth, 2021. http://d-nb.info/1229505393/34.
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Barbre, Evan Allen. "LASER ETCHED PMMA MICROFLUIDIC CHIP DESIGN AND MANUFACTURE WITH APPLICATIONS IN CAPILLARY ZONE ELECTROPHORESIS." DigitalCommons@CalPoly, 2011. https://digitalcommons.calpoly.edu/theses/448.
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This thesis encompasses a feasibility study of using low-cost materials to manufacture microfluidic chips that can perform the same functions as chips manufactured using traditional methods within an acceptable range of efficiency of chips created with more exotic methods and materials. The major parts of the project are the selection and characterization of the fabrication methods for creating the channels for fluid flow, the methods for sealing the channels to create a usable chip and the electrophoretic separations of carboxylated microspheres of different potentials. In this work we seek to answer the question if laser-etched PMMA microfluidic chips are comparable in functionality to microfluidic chips created with PDMS or glass. In the process of answering this question we will touch on FEA modeling, characterization of the manufacturing process and multiple prototype designs while keeping within the low-cost theme.
The purpose of capillary electrophoresis is to separate proteins based on their inherent electric charge. Capillary electrophoresis is a standard chip design used in the microfluidics world to prove a new fabrication method or chip material before branching out to other experiments because it is a fairly simple and robust design. Common problems associated with the manufacturing methods and materials were taken into account such as electroosmotic flow and chip sealing. CZE designs from literature were referenced to create a chip that would separate carboxylated microbeads with reasonable resolution. Wire electrodes were affixed to the chip to induce electric fields for the electrophoresis experiments. The goal of this thesis is to prove the manufacturing methods and attain results within 70% of literature standards.
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Bishop, Sandra Charlotte. "Advanced capillary electrophoretic techniques for the detection of date-rape and club drugs for a forensic setting." Ohio : Ohio University, 2004. http://www.ohiolink.edu/etd/view.cgi?ohiou1107528810.
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Xu, Jiang. "Contribution à la fabrication de nanoparticules en utilisant des techniques microfluidiques et applications à la libération d'actifs." Thesis, Bordeaux, 2016. http://www.theses.fr/2016BORD0122/document.
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Les nanoparticules de polymère (NP) sont une technologie prometteuse pour la libération contrôlée d’actifs . Elles permettent de protéger les drogues et de les délivrer de façon continue. Toutefois pour que cette technologie devienne mature, il est nécessaire de mieux contrôler la synthèse de ces objets. Afin d'atteindre cet objectif, cette thèse propose deux nouvelles méthodes de synthèse basée sur les technologies microfluidiques. Ces méthodes permettent d’encapsuler des drogues hydrophiles et hydrophobes et permettent d’atteindre des taux d’encapsulation supérieurs à ceux mesurés dans la littérature (80% avec une masse de 20% de drogue). Ces approches ont été appliquées à l'encapsulation de l'oxyde de ferPolymeric nanoparticle (NP) drug carriers present a promising technology for controlled releasesince they are capable of improving the encapsulation efficiency and stability of the drugs inside theNPs and also able to provide effective drug levels over a longer period of time, compared totraditional therapy. However, before the NP drug delivery technology becomes a reality, importantparameters of NPs like size, drug loading ability and sustained release kinetics must be wellinvestigated and optimized in order to minimize the adverse effects of chemotherapeutic compoundsand prolong the drug releasing profile in a controlled manner.In order to accomplish this objective, this thesis proposed two novel methods for synthesis of NPs asdrug delivery carriers, with assistance from bulk and microfluidic technologies, for hydrophobic andhydrophilic drugs, individually.Encapsulation efficiency as high as 80% is reached with a mass loading of 20%. We extend ourapproaches to the encapsulation of iron oxide
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Campagnolo, Lucie. "Optical feedback interferometry sensing technique for flow measurements in microchannels." Phd thesis, Institut National Polytechnique de Toulouse - INPT, 2013. http://tel.archives-ouvertes.fr/tel-01068169.
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Le phénomène d'interférométrie par réinjection optique, ou effet self-mixing dans un laser permet de concevoir des capteurs non-invasifs, auto-alignés, ne nécessitant que peu d'éléments optiques et simples à implémenter. Ce type de capteur permet de mesurer avec la précision propre à l'interférométrie laser le déplacement, la vitesse ou la position de cibles dite coopératives (cibles réfléchissantes ou fortement diffusantes). Dans cette étude, ce type de capteurs est appliqué à la mesure de profil d'écoulement des fluides dans des microcanaux. Le faible coût et la polyvalence des capteurs à réinjection optique sont d'un grand intérêt dans l'industrie biomédicale et chimique, ainsi que pour la recherche en mécanique des fluides. Dans un premier temps, et en se basant sur les études réalisées dans des macro-canaux, nous avons proposé un modèle d'interferométrie par réinjection optique dans une diode laser lorsque la cible est constitué de particules en mouvement, en suspension dans un liquide. A partir de ce modèle, nous avons étudié expérimentalement l'impact du volume de mesure ainsi que du type de particules (taille et concentration) sur le signal mesuré. Nous avons ensuite proposé des méthodes de traitement du signal permettant de calculer le calcul du débit du fluide, ainsi que sous certaines conditions identifiées, la vitesse locale en tout point d'un microcanal. Ces études préliminaires nous ont permis de reconstruire le profil d'écoulement de différents liquides dans des canaux de 320µm de diamètre. Enfin, nous avons comparé les performances du capteur développé dans cette thèse avec un capteur basé sur la technique du Dual-Slit, technique déjà validée pour la microfluidique, en mesurant le profil d'écoulement dans un canal à section rectangulaire de 100x20µm.
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Duford, David. "Instrumentation, fabrication techniques and method development for sample introduction, preparation and extraction on centrifugal microfluidic devices in motion." Thesis, McGill University, 2012. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=110441.
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A growing number of pollutants are being shown to have a large environmental and health impact resulting in stricter legislative limits. Increased environmental monitoring is forcing analytical chemists to consider automating and miniaturizing current standard methods. Instrumentation and sample handling techniques for centrifugal microfluidic devices in motion have been developed with the objective of integrating multi-step reactions into a single device for the analysis of environmental solid samples.In order to study and optimize centrifugal microfluidic devices in motion, motorized stages integrating a camera, strobe and a variety of other peripheral components were developed. These allowed precise control of the devices throughout the methods' spin sequences and simultaneous acquisition of a series of stop action photographs of the devices.Non-contact methodologies for sample introduction, preparation and extraction on centrifugal microfluidic devices in motion are presented. To achieve this, hybrid fabrication techniques including the use of 3D printers were investigated and a World-to-Disk interface permitting the introduction of a solution gradient to a spinning device was developed. The interaction of integrated mobile magnets with a series of fixed magnets placed below the spinning devices was also investigated resulting in the development of both a magnetically actuated solid sample preparation and a magnetically actuated liquid-solid extraction technique. New automated and miniaturized methods for the analysis of environmentally important species such as polycyclic aromatic hydrocarbons and pesticides in solid samples are presented.Les polluants ont des impacts importants sur la santé et l'environnement résultant à des restrictions accrues des limites législatives. Cette surveillance environnementale accrue pousse les chimistes analytiques vers l'automatisation et la miniaturisation des méthodes de référence actuelles. L'analyse d'échantillons environnementaux solides bénéficiera de cette envolée par le développement de nouveaux instruments et techniques de manipulation d'échantillon via des dispositifs microfluidiques centrifuges qui intègrent des réactions à étapes multiples sur un dispositif unique.Afin d'étudier et d'optimiser les dispositifs microfluidiques centrifuges en mouvement, des plateformes motorisées qui incluent une caméra, une lumière stroboscopique et une variété d'autres composantes périphériques ont été développées. Celles-ci ont permis le contrôle efficace des dispositifs tout au long des séquences giratoires et l'acquisition simultanée de séries de photographies en arrêt sur image.Des méthodologies sont présentées pour l'introduction, la préparation et l'extraction d'échantillons sur des dispositifs microfluidiques centrifuges en mouvement. Ceci fut réalisé grâce à la recherche de techniques de fabrication hybrides incluant l'utilisation d'imprimantes 3D menant au développement d'une interface permettant l'introduction de solutés à concentrations variables aux dispositifs en mouvement. De plus, l'interaction d'aimants mobiles intégrés avec une série d'aimants fixes placée sous les dispositifs en mouvement a mené au développement des techniques de préparation d'échantillons solides par force magnétique et d'extraction liquide-solide d'échantillons par force magnétique. De nouvelles méthodes automatisées et miniaturisées ont été développées pour l'analyse d'espèces environnementales importantes telles que les hydrocarbures polycycliques aromatisés et les pesticides dans des échantillons solides.
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Shrestha, Ramesh. "Micro-Pipette Thermal Sensor: A Unique Technique for Thermal Characterization of Microfluids, Microspheres, and Biological Cells." Thesis, University of North Texas, 2020. https://digital.library.unt.edu/ark:/67531/metadc1703406/.
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In this research work, an innovative method for measurement of thermal conductivity of a small volume of liquids, microsphere, and the single cancer cell is demonstrated using a micro-pipette thermal sensor (MPTS). The method is based on laser point heating thermometry (LPHT) and transient heat transfer. When a single pulse of a laser beam heats the sensor tip which is in contact with the surrounding liquids or microsphere/cells, the temperature change in the sensor is reliant on the thermal properties of the surrounding sample. We developed a model for numerical analysis of the temperature change using the finite element method (FEM) in COMSOL. Then we used MATLAB to fit the simulation result with experiment data by multi-parameter fitting technique to determine the thermal conductivity. To verify the accuracy in the measurement of the thermal conductivity by the MPTS method, a 10µl sample of de-ionized (DI) water, 50%, and 70% propylene glycol solution were measured with deviation less than 2% from reported data. Also, to demonstrate that the method can be employed to measure microparticles and a single spherical cell, we measured the thermal conductivity of poly-ethylene microspheres with a deviation of less than 1% from published data. We estimated the thermal conductivity of two types of cell culture growth media for the first time and determined the thermal conductivity of cancerous Jurkat Clone E6-1 to be 0.538 W/m.K ± 2%. Using the sensor of 1-2μm tip size, we demonstrated the MPTS technique as a highly accurate technique for determining the thermal conductivity of microfluidic samples, microparticles, biological fluids, and a non-invasive method for measuring the thermal conductivity of single cancer cell. This MPTS technique can be beneficial in developing a diagnosis method for the detection of cancer at an early stage. We also compared three effective thermal conductivity models for determining the weight percentage of Jurkat cell, considering water and protein as the major constituents. We discovered that a combination of Maxwell-Euken and effective medium theory model provides the closest approximation to published data and, therefore, recommend for the prediction of the cell composition.
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Bushman, Sarah Mansfield. "The Development of Micro- and Nano-scale Techniques for Studying Cancer Cell Invasion." The Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1492775878121827.
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TRICHUR, RAMACHANDRAN KRISHNAN. "DEVELOPMENT OF POLYMER MEMS STRUCTURES FOR LAB-ON-A-CHIPS USING UV-LIGA AND INJECTION MOLDING TECHNIQUES." University of Cincinnati / OhioLINK, 2003. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1061211852.
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Mitchell, Haydn Thomas. "AN INVESTIGATION OF POLY(N-ISOPROPYLACRYLAMIDE) FOR APPLICATIONS WITH MICROFLUIDIC PAPER-BASED ANALYTICAL DEVICES." DigitalCommons@CalPoly, 2014. https://digitalcommons.calpoly.edu/theses/1248.
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N,N′-methylenebisacrylamide-crosslinked poly(N-isopropylacrylamide), also known as P(NIPAM), was developed as a fluid delivery system for use with microfluidic paper-based analytical devices (microPADs). MicroPADs are postage-stamp-sized devices made out of paper that can be used as platforms for low-cost, simple-to-use point-of-care diagnostic assays. P(NIPAM) is a thermally responsive polymer that absorbs aqueous solutions at room temperature and will expel the solutions to microPADs when heated. The fluid delivery characteristics of P(NIPAM) were assessed, and P(NIPAM) was able to deliver multiple solutions to microPADs in specific sequences or simultaneously in a laminar-flow configuration. P(NIPAM) was then shown to be suitable for delivering four classes of reagents to microPADs: small molecules, enzymes, antibodies and DNA. P(NIPAM) successfully delivered a series of standard concentrations of glucose (0 – 5 mM) to microPADs equipped to perform a colorimetric glucose assay. The results of these tests were used to produce an external calibration curve, which in turn was used to determine accurately the concentrations of glucose in sample solutions. P(NIPAM) successfully delivered fluorescein-labeled IgG and fluorescein-labeled oligonucleotides (20 base pairs) to microPADs in a variety of concentrations. P(NIPAM) also successfully delivered horseradish peroxidase (HRP) to microPADs, and it was determined that HRP could be stored in P(NIPAM) for 35 days with minimal loss in activity. The combination of P(NIPAM) with microPADs will allow for more complex assays to be performed with minimal user input, will facilitate the preparation of external calibration curves in the field, and may be useful in extending the shelf life of microPADs by stabilizing reagents.
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Pilát, Zdeněk. "Optical Micromanipulation Techniques Combined with Microspectroscopic Methods." Doctoral thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2015. http://www.nusl.cz/ntk/nusl-234266.
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Předložená dizertační práce se zabývá kombinací optických mikromanipulací s mikrospektroskopickými metodami. Využili jsme laserovou pinzetu pro transport a třídění živých mikroorganismů, například jednobuněčných řas, či kvasinek. Ramanovskou spektroskopií jsme analyzovali chemické složení jednotlivých buněk a tyto informace jsme využili k automatické selekci buněk s vybranými vlastnostmi. Zkombinovali jsme pulsní amplitudově modulovanou fluorescenční mikrospektroskopii, optické mikromanipulace a jiné techniky ke zmapování stresové odpovědi opticky zachycených buněk při různých časech působení, vlnových délkách a intenzitách chytacího laseru. Vyrobili jsme různé typy mikrofluidních čipů a zkonstruovali jsme Ramanovu pinzetu pro třídění mikro-objektů, především živých buněk, v mikrofluidním prostředí.
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Bishop, Sandra Charlotte. "Advanced Capillary Electophoretic Techniques for the Detection of Date-Rape and Club Drugs for a Forensic Setting." Ohio University / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1107528810.
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Vyas, Chandni Atul. "Rapid Detection of Biogenic Amines using Capillary Electrophoresis and Gradient Elution Isotachophoresis." Diss., Temple University Libraries, 2010. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/112673.
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ChemistryPh.D.
The metabolism of amino acids produces important chemical signaling molecules called neurotransmitters, which are responsible for carrying out important actions within the human body. There are approximately one hundred identified neurotransmitters. Neurotransmitter study is important due to their involvement in biological, physiological, pharmacological, and pathological functions. Commonly employed methods for neurotransmitter detection are mainly based upon microdialysis. However, the methods suffer from disadvantages. Microdialysis fails to determine the absolute concentration of analytes and therefore requires it to be tied in with an analytical technique such as high performance liquid chromatography or capillary electrophoresis. Although high performance liquid chromatography is the most powerful analytical technique to date, it necessitates high maintenance and suffers from poor temporal resolution. While capillary electrophoresis affords more rapid separations than high performance liquid chromatography, it suffers from poor concentration limits of detection and requires large sample dilutions of highly conductive samples, such as biological fluids. Consequently, research is focused on detection of various amino acids and neurotransmitters employing novel analytical techniques along with traditional capillary electrophoresis. First, a method was developed using traditional capillary electrophoresis with laser induced fluorescence detection to detect two major excitatory neurotransmitters, glutamate and aspartate in planaria. The method was later applied to detect several biogenic amines using micellar electrokinetic chromatography with laser induced fluorescence detection in planaria to study the effect of feeding on the levels of biogenic amines within individual planaria homogenates. The concentration sensitivity issue of capillary electrophoresis led to the use of a new method for sensitive neurotransmitter measurements, gradient elution isotachophoresis. Gradient elution isotachophoresis is an efficient capillary-based enrichment and separation technique based on balancing hydrodynamic counter-flow against electrophoresis. Enrichment is achieved with the aid of high concentrations of leading electrolyte in the counter-flow solution that creates an ionic interface near the capillary inlet. Discrete electrolyte spacers or carrier ampholyte mixtures are used to separate analyte zones. The method was applied to the enrichment and separation of physiologically relevant concentrations of aspartate and glutamate labeled with dansyl chloride, phenyl isothiocyanate, or carboxyfluorescein, succinimidyl ester in artificial cerebrospinal fluid using ultraviolet absorbance detection. Finally, gradient elution isotachophoresis was combined with capillary zone electrophoresis to eliminate the use of spacers and provide rapid separations and enrichment. The technique was applied for the detection of biogenic amines in a glass microfluidic device.
Temple University--Theses
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Samouda, Feriel. "Développement de la technique de vélocimétrie par marquage moléculaire pour l'étude expérimentale des micro-écoulements gazeux." Thesis, Toulouse, INSA, 2012. http://www.theses.fr/2012ISAT0034/document.
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Ce travail de thèse porte sur le développement de la technique de Vélocimétrie par Marquage Moléculaire (Molecular Tagging Velocimetry - MTV) pour l’étude expérimentale des micro-écoulements gazeux internes. Les micro-écoulements gazeux sont des écoulements raréfiés, caractérisés par un nombre de Knudsen non négligeable. L’analyse de la littérature montre un besoin crucial de données expérimentales de grandeurs locales relatives aux micro-écoulements gazeux. Ces données permettraient une discussion pertinente de la précision et des limites d’applicabilité des différents modèles théoriques proposés dans la littérature pour l’étude du régime de glissement, régime raréfié le plus souvent rencontré en microfluidique gazeuse. Dans cette optique, un banc d’essais expérimental a été développé pour la mesure de champs de vitesses par MTV. La technique consiste à suivre des molécules traceuses d’acétone introduites dans le gaz en écoulement et qui deviennent phosphorescentes lorsqu’elles sont excitées par une source lumineuse UV. Les différents compromis pris en compte pour le développement de ce banc (choix du traceur et du matériau, conception du canal instrumenté,…), ainsi que les techniques d’acquisition et de traitement de signal sont détaillés dans le manuscrit. L’analyse expérimentale commence par une étude du signal de phosphorescence de l’acétone. Ensuite, la technique de vélocimétrie par marquage moléculaire est validée par la mesure de champs de vitesses dans des écoulements laminaires confinés en régime non raréfié. Les résultats obtenus sont comparés à des profils de vitesse théoriques d’un écoulement de Poiseuille à pression atmosphérique. Enfin, les premiers résultats obtenus à basse pression sont présentés et commentés. La détection du signal à un niveau de pression de 1kPa est encourageante et offre de nombreuses perspectives pour l’exploration d’écoulements en régime raréfiéThis thesis focuses on the development of Molecular Tagging Velocimetry (MTV) technique for the experimental analysis of internal microflows of gases. Gaseous microflows are rarefied flows characterized by a non-negligible Knudsen number. A literature review highlights a crucial need of experimental data on velocity fields within gaseous microflows. These data are required for a relevant discussion on the validity and limits of applicability of the different boundary conditions proposed in the slip flow, which is a regime often encountered in gaseous microsystems. An experimental setup has been designed for analyzing by MTV the velocity distribution in microchannels. The technique consists in detecting the displacement of acetone molecules, introduced as tracers in a gas flow; these molecules exhibit phosphorescence once excited by a UV light source. The various compromises taken into account for the setup design (choice of tracer, laser, channel material and design, camera and intensifier…), as well as the acquisition and processing techniques are detailed in the manuscript. The experimental analysis starts with a study of the acetone phosphorescence signal. Then, the MTV technique is validated by velocity field measurements in internal laminar flows through a rectangular minichannel in non-rarefied regime. The obtained results are successfully compared to the theoretical velocity profile of a Poiseuille flow. Finally, preliminary results obtained at lower pressures are presented and commented. The signal detection at a pressure level as low as 1 kPa is encouraging and draws various perspectives for the exploration of rarefied regimes
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Tageson, Mackenzie Elizabeth. "FUNCTIONAL 3-D CELLULOSE & NITROCELLULOSE PAPER-BASED, MULITPLEX DIAGNOSTIC PLATFORMS WITHOUT COUPLING AGENTS." DigitalCommons@CalPoly, 2013. https://digitalcommons.calpoly.edu/theses/1128.
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The purpose of this thesis was to demonstrate device functionality of 3-D paper-based, multiplex platforms, µPADs, without the use of coupling agents between layers. Previously, these platforms were fabricated with double-sided tape and cellulose powder to try to augment proper fluid routing, but difficulties with this method occurred. An acrylic housing unit with strategically placed pressure tabs was designed to aid horizontal and vertical fluid routing through the platform, thus eliminating the inconsistencies associated with coupling agents. Channel characterization studies, a COMSOLTM simulation, and development time studies were performed to aid device design and demonstrate device functionality.
The implementation of this µPAD platform as a diagnostic instrument was validated via lateral flow immunoassays utilizing both biotinylated antibodies and biotinylated aptamers as capture reagents. Successful detection of the target analyte, IgE, as well as successful fluid routing through multiple layers of membrane was demonstrated by immunoassays performed on 3-D, multiplex platforms. Another important result determined the aptamers’ ability to detect IgE to be statistically the same as the antibodies’ ability; thus confirming aptamers as viable capture reagent alternatives to antibodies in lateral flow assays. Overall, this research project was performed to develop and validate via experiment a prototype paper-based microfluidic diagnostic device, µPAD, with the capability to detect multiple biomarkers on one platform.
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Martim, Hamilton de. "Desenvolvimento de uma técnica para seleção de espermatozoides em amostra seminal não processada para utilização na injeção intracitoplasmática de espermatozoides." Universidade de São Paulo, 2017. http://www.teses.usp.br/teses/disponiveis/5/5153/tde-11092017-101455/.
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Durante a injeção intracitoplasmática de espermatozoides (ICSI) seleciona-se um espermatozoide móvel e morfologicamente normal para injeção em ovócito maduro. Evidências recentes indicam que mesmo espermatozoides aparentemente normais podem ocultar defeitos em nível molecular. O principal objetivo deste trabalho foi a descrição de um novo método capaz de selecionar espermatozoides maduros a partir de amostras não processadas em procedimento de ICSI. Em um estudo comparativo e prospectivo testou-se uma gota estendida modificada. A \"gota estendida com mecanismo contracorrente\" - GEMC foi montada em uma placa de ICSI padrão a partir de seis gotas de meio de cultivo (10 ?L). O posicionamento e união precisa das gotas deram origem a dois reservatórios e um canal, resultando em um fluxo de líquido através do canal. A adição de uma solução de PVP (polivinilpirrolidona) gerou um gradiente de viscosidade no final do circuito. Amostras seminais foram obtidas de 40 pacientes inférteis. Cada amostra seminal foi dividida em 4 alíquotas: uma alíquota para o processamento por centrifugação em gradiente de densidade (CGD), uma alíquota para a GEMC utilizando amostras não processadas, uma alíquota para a GEMC utilizando amostras processadas e uma alíquota para controle. Nos grupos GEMC uma média de 200 espermatozoides foram consecutivamente coletados, sem seleção, no reservatório de captura utilizando-se uma micropipeta de injeção como no procedimento convencional de ICSI. A morfologia espermática foi avaliada e demonstrou melhora, comparando-se com os controles, em todos os tratamentos utilizados. A imaturidade da cromatina foi avaliada utilizando-se o teste do azul de anilina. Em relação à imaturidade, 100% dos homens obtiveram melhores resultados tanto após o preparo por CGD quanto utilizando o método GEMC. Isto se refletiu em uma redução das formas imaturas de 28.65 ± 8.97% no sêmen fresco para 17.29 ± 7.72% após processamento por CGD (P < 0.01). Uma redução ainda maior nas formas imaturas foi obtida após o método GEMC quando comparado com o processamento por CGD: 0.89 ± 1.31% (P < 0.01) utilizando-se sêmen fresco e 1.05 ± 1.63% (P < 0.01) utilizando-se amostras processadas. Um novo método unindo seleção e captura de espermatozoides em um mesmo procedimento de ICSI foi descrito e testado. O método GEMC seleciona espermatozoides de forma fácil e permite o uso direto de amostras não processadas em procedimentos de ICSI. Este método seleciona espermatozoides maduros com mais eficiência do que o processamento por CGD. Novos estudos são necessários para se analisar o impacto do método nas taxas de fertilização, desenvolvimento embrionário, gravidez, implantação e abortamentoDuring intracytoplasmic sperm injection (ICSI) a motile spermatozoon with normal morphology is visually selected for insemination of an oocyte. Recent evidence indicates that even though the sperm appears morphologically normal, a possibility of defects at the molecular level still exists. The main objective of this work was to describe a novel approach capable of selecting mature spermatozoa from unprocessed semen sample in a one-step ICSI procedure. A modified extended drop was tested in a prospective comparative study. The \"Gota Estendida com Mecanismo Contracorrente - GEMC\" (Positive Rheotaxis Extended Drop - PRED) was assembled on a standard ICSI dish and consisted of six culture medium droplets (10 ?L). The precise merging of the drops created two reservoirs and a channel therefore the fluid flew through the channel. The addition of a PVP solution created a viscosity gradient in the final sector of the circuit. Semen samples were taken from 40 subfertile men. Each semen sample was divided into four aliquots: one aliquot for density gradient centrifugation (DGC), one aliquot for GEMC using fresh semen, one aliquot for GEMC using processed semen and one aliquot for the control. In GEMC a mean of 200 spermatozoa were collected consecutively, without selection, from the outlet reservoir with an injecting pipette as for conventional ICSI procedure. Sperm morphology was assessed and resulted in improvement compared to controls in all treatments. Chromatin immaturity was assessed using aniline blue assay. Regarding to chromatin immaturity, 100% of men had better results after DGC preparation and GEMC approach. This was reflected in a mean reduction from 28.65 ± 8.97% uncondensed chromatin in the native ejaculates to 17.29 ± 7.72% in DGC processed semen (P < 0.01). An even greater reduction was achieved after GEMC approach showing a mean of 0.89 ± 1.31% uncondensed chromatin compared to DGC processed sample (P < 0.01). A novel one-step ICSI approach joining sperm selection and recovery was developed and tested. This GEMC approach can select sperm easily and permits the direct use of native semen in ICSI. This approach can select sperm with lower chromatin immaturity than DGC method. Further studies need to access its relation to fertilization, embryo development, pregnancy, implantation and miscarriage rates
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Paoli, Roberto. "Cell culture interfaces for different organ-on-chip applications: from photolithography to rapid-prototyping techniques with sensor embedding." Doctoral thesis, Universitat de Barcelona, 2019. http://hdl.handle.net/10803/668376.
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Despite the last 60 years have seen major advances in many scientific and technological inputs of drug Research and Development, the number of new molecules hitting the market per billion US dollars of R&D spending has been declined steadily during the same period. The current scenario highlights the need for new research tools to enable reduce costly animal and clinical trials while providing a better prediction about drug efficacy and security in humans
A recent emerging approach to improve the current models is emerging from the field of microfluidics, which studies systems that process or manipulate tiny amounts of fluids using channels with dimensions of tens to hundreds of micrometers. Combining microfluidics with cell culture, scientists gave rise to a new field named “Organ-on-chip” (OOC). Microfluidic OOCs are advanced platforms designed to mimic physiological structures and continuous flow conditions, thus allowing the culture of cells in a friendlier microenvironment.
This thesis, titled “Cell culture interfaces for different organ-on-chip applications: from photolithography to rapid-prototyping techniques with sensor embedding”, aims to design, simulate and test new OOC devices to reproduce cell culture interface under flow conditions. The work has a focus on the exploration of novel fabrication techniques which enable rapid prototyping of OOC devices, reducing costs, time and human labor associated to the fabrication process. The final objective is to demonstrate the viability of the devices as research tools for biological problems, applying them to the tubular kidney and the blood brain barrier (BBB).
To achieve the objective, at least three device version have been developed: 1) OOCv1, fabricated by multilayer PDMS soft lithography; 2) OOCv2, fabricated in thermoplastic by layered object manufacturing using both a vinyl cutter and a laser cutter, integrating standard fluidic connectors alone (OOCv2.1) or together with embedded electrodes (OOCv2.2); 3) OOCv3 using a mixed technique of laser cut and 3D printing by stereolithography. All devices are fabricated using biocompatible materials with high optical quality and an embedded commercial membrane.
The biological experiments with renal tubular epithelial cells, realized on OOCv1 and OOCv2.1 devices, demonstrated the viability of the device for culturing cells under flow conditions. The study realized on fatty acid oxidation and accumulation in cells exposed to physiological and diabetogenic oscillating levels of glucose suggest a possible positive role of shear stress in activation of fatty acid metabolism. The studies were performed using a compact experimental unit with embedded flow control which reduce significatively the complexity and cost of the fluidic experimental setup.
The biological experiments on the BBB confirmed viability of OOCv2.1 and OOCv2.2 for compartmentalized co-culturing of endothelial cells and pericytes. The formation and recovery of the barrier after disruptive treatment has been assessed using different techniques, including immunostaining, fluorescence and live phase contrast imaging, and electrical impedance spectroscopy. The repeatability of measurements using electrodes was verified. A model to classify measurements from different timepoints has been developed, resulting in accuracy of 100% in learning and 90% in testing case. Results are confirmed by imaging data, which also suggest a critical role of pericytes in the development, maintenance, and regulation of BBB, in accordance with the literature.En los últimos años está emergiendo una nueva propuesta para mejorar los modelos actuales en el estudio de nuevos fármacos. Mediante la fusión de cultivos celulares y microfluídica ha nacido un nuevo campo de aplicación denominado “Órgano-en-un-chip” (OOC), donde se recrea un entorno fisiológico capaz de reproducir unidades funcionales mínimas de diversos órganos del cuerpo humano. Un elemento importante para el desarrollo de dispositivos OOC es la reproducción de zonas de interacción entre varios tejidos formados por diferentes tipos celulares. Esta tesis, titulada “Interfaces de cultivo celular para diferentes aplicaciones de OOC: desde fotolitografía a técnicas de prototipado rápido con inclusión de sensores”, tiene como objetivo el diseño, simulación y evaluación de dispositivos OOC capaces de reproducir superficies de contacto de tejidos contiguos expuestos a flujo. El trabajo está enfocado a la exploración de nuevas técnicas de fabricación que permitan el prototipado rápido de dispositivos OOC, reduciendo costes, tiempo y mano de obra asociada a dicha fabricación. El objetivo final es demostrar la utilidad de los dispositivos como herramientas de investigación para problemas biológicos, aplicándolos en esta tesis al estudio del túbulo renal y de la barrera hematoencefálica. Para ello se han fabricado tres versiones de dispositivos: 1) OOCv1 fabricado por litografía suave en múltiples capas de PDMS; 2) OOCv2 fabricado con cortadora de vinilo y cortadora láser en múltiples capas de materiales termoplásticos y con electrodos integrados en la versión OOCv2.2; 3) OOCv3 fabricado mediante impresión 3D por esterolitografía. Todos los dispositivos están hechos de materiales biocompatibles de alta calidad óptica, con conectores fluídicos y una membrana comercial integrada. Los experimentos biológicos sobre túbulo renal, realizados en los dispositivos OOCv1 y OOCv2, han demostrado la viabilidad de los dispositivos, integrados con un sistema de flujo, para estudios de la metabolización de ácidos grasos en el riñón relacionados con condiciones diabetogénicas. Los experimentos biológicos sobre la barrera hematoencefálica han confirmado la viabilidad de OOCv2 para el cocultivo compartimentado de células endoteliales de cerebro y pericitos. La integración de electrodos en el OOCv2.2 ha demostrado ser una técnica fiable para la medición de la integridad de barreras biológicas de modo no-invasivo, libre de etiqueta (“label-free”), y a tiempo real gracias a la espectroscopía de impedancia.
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Yu, Wei. "Development of an elongational-flow microprocess for the production of size-controlled nanoemulsions : application to the preparation of composite and hybrid polymeric microparticles." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE027/document.
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L’objectif de ce travail fut de développer et d’étudier les performances d’un microprocédé basse pression à écoulement élongationnel pour la production de nanoémulsions polymérisables de tailles contrôlées et de distributions de taille étroites. Le diamètre des nanogouttelettes a pu être précisément ajusté dans la gamme 50-300 nm en modifiant simplement les paramètres de procédé : le débit réciproque au travers du micromélangeur, le nombre de cycles et la dimension caractéristique du microcanal. Les nanoémulsions produites furent, dans une seconde étape, polymérisées par voie thermique ou par irradiation UV afin de générer des suspensions colloïdales de nanoparticules de polymère de tailles également contrôlées (87-360 nm). Un monomère, un agent de réticulation ainsi qu’un amorceur thermique ou photochimique appropriés furent par la suite ajoutés au milieu continu de ces nanosuspensions. Les solutions résultantes servirent comme phases dispersées dans des générateurs microfluidiques de gouttelettes à capillaires. Les microgouttelettes de taille contrôlée ainsi produites furent polymérisées en ligne par irradiation UV pour donner lieu à des microsphères ou à des microparticules coeur-écorce composites de polymère toutes deux dopées avec des nanoparticules de polymère. Des microparticles composites et hydrides comportant des nanoparticules d’or dans le coeur et d’argent dans l’écorce furent également obtenues grâce à la réduction photochimique in situ des sels précurseurs lors de la photopolymérisation des microgouttelettes. Ce travail a démontré l’efficacité d’un nouveau dispositif microfluidique basse énergie pour la production de nanoémulsions et leur emploi pour la synthèse de matériaux polymères morphologiquement complexesThe aim of this work was to develop and to study the performances of a low pressure elongational-flow microprocess for the production of size-controlled polymerizable nanoemulsions with narrow size distributions. Nanodroplets diameter was easily tuned in the size range 50-300 nm by varying the process parameters, namely the reciprocating flow rate through the micromixer, the number of cycles and the characteristic dimension of the microchannel. Obtained nanoemulsions were in a second step thermally or UV-assisted polymerized to give colloidal suspensions of size-tunable polymer nanoparticles (87-360 nm). Then, a proper monomer, crosslinker and thermal- or photo-initiator were added to the continuous phase of these nanosupensions. The resulting mixtures were used as the dispersed phases of two different capillaries-based microfluidic droplet generators. The produced sizecontrolled microdroplets were finally UV polymerized online and plain as well as core-shell composite polymeric microparticles doped with lower scale polymer nanoparticles were obtained. Composite/hybrid polymeric core-shell microparticles were also synthesized for which gold nanoparticles in the core and silver nanoparticles in the shell were synthesized in situ from their salt precursors during microdroplets polymerization. This work has demonstrated the high efficiency of a novel low energy microfluidic emulsification device for the production of nanoemulsions which were used for the synthesis of morphologically complex polymeric materials
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Paiola, Johan. "Écoulement d'un fluide à seuil dans un milieu poreux." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS031/document.
Full textAbstract:
Solides élastiques au repos, les fluides à seuil s’écoulent comme un liquide au-delà d’une certaine contrainte. Plusieurs applications industrielles concernent l’écoulement de ces fluides dans des milieux poreux. On peut citer par exemple les émulsions dans le processus de récupération du pétrole, les opérations de cimentation dans le sol, ou le nettoyage d’un sol contaminé par une boue. Pour ces applications, il est nécessaire de connaitre la pression nécessaire pour un débit voulu à la sortie du milieu poreux. Dans de tels cas, l’écoulement est perturbé par la complexité de la géométrie. Les modèles développés pour décrire la loi de Darcy supposent une loi rhéologique appliquée localement, mais ces modèles décrivent mal ce type d’écoulement. De plus, des effets complexes peuvent s’ajouter comme le glissement à la paroi ou la thixotropie. Dans cette thèse, nous étudions l’écoulement de carbopol (ETD 2050) à travers différentes géométries. Tout d’abord au rhéomètre, nous montrons que le fluide, sous certaines conditions, correspond bien à un fluide à seuil modèle. Nous démontrons que le protocole expérimental utilisé est très important et qu’un comportement thixotropique peut apparaitre s’il n’est pas respecté. Ce comportement apparait notamment lorsque le fluide reste sous le seuil, l’impact augmentant avec le temps d’attente. Ensuite, nous comparons la loi d’écoulement obtenue au rhéomètre à l’écoulement dans un canal droit obtenu par microfabrication. Nous montrons alors l’importance du glissement proche du seuil et ses conséquences sur la loi d’écoulement. Enfin nous étudions l’écoulement du carbopol dans un milieu poreux. Le milieu poreux de 5x5cm est obtenu par microfabrication. La largeur moyenne des canaux est égale à celle du canal droit. Nous avons développé une nouvelle méthode de mesure des champs de vitesse. Nous montrons l’apparition d’une chenalisation de l’écoulement à travers quelques canaux du milieu poreux. Nous comparons ensuite la loi d’écoulement du milieu poreux à celle obtenue dans le canal droit. On remarque que la vitesse d’écoulement est plus faible dans le milieu poreux que dans le canal droitElastic solids at rest, yield stress fluids flow like a liquid beyond a certain stress. Many industrial applications required the flow of these fluids in porous media, for example: the emulsion flow in oil recovery processes, the cementing operations in the ground, or the cleaning of sludge in a contaminated soil. For many applications, it could be interesting to know the pressure required for a desired flow rate. In such cases, the flow behavior of the fluid is complicated by the complexity of the geometry. The models developed to describe Darcy's law assume a rheological law applied locally, but these models poorly describe this type of flow. Furthermore, complex effects can be added like the wall slip or the thixotropy. In this thesis, we study the flow of carbopol (ETD 2050) through different geometries. First we show that the fluid, for some conditions, corresponds to model yield stress fluids. The experimental protocol used is very important and a thixotropic behavior can appear if it is not respected. This behavior appears especially when the fluid remains below the yield stress, the impact increases with the waiting time. We then compare the flow law obtained by rheometer in a straight channel obtained by microfabrication. We show the importance of the wall slip near the yield stress and the impact on the flow law. Finally, using a new method to measure the velocity fields developed during this thesis, we study the flow of carbopol in a porous medium. This porous medium of 5x5cm is obtained by microfabrication. The mean width of the channels is equivalent to the one of the straight channel. We show the emergence of a channeling flow through some channels of the porous medium. We then compare the flow law of the porous medium to the one obtained in the straight channel. It can be observed that the flow rate is lower in the porous medium than in the straight channel