To see the other types of publications on this topic, follow the link: Particle manipulation.
Dissertations / Theses on the topic 'Particle manipulation'
Create a spot-on reference in APA, MLA, Chicago, Harvard, and other styles
Consult the top 50 dissertations / theses for your research on the topic 'Particle manipulation.'
Next to every source in the list of references, there is an 'Add to bibliography' button. Press on it, and we will generate automatically the bibliographic reference to the chosen work in the citation style you need: APA, MLA, Harvard, Chicago, Vancouver, etc.
You can also download the full text of the academic publication as pdf and read online its abstract whenever available in the metadata.
Browse dissertations / theses on a wide variety of disciplines and organise your bibliography correctly.
1
Hill, Martyn. "Ultrasonic resonators for particle manipulation." Thesis, University of Southampton, 2004. https://eprints.soton.ac.uk/46529/.
Full textAbstract:
Ultrasonic standing waves can be used to generate radiation forces which act on particles within a fluid. These forces may be useful for manipulation, separation, or fractionation of these particles. This thesis describes the use and modelling of a number of devices which use such acoustic radiation forces. Initially, the design and testing of a large (multiple wavelength) flow-through ultrasonic separation device is described. This device demonstrated for the first time that flow-through ultrasonic filtration could be made to work successfully on this scale without having to rely on acoustically transparent membranes. Three models are used to examine the behaviour of the resonator. The electro-acoustic model is then used to analyse the performance of two smaller resonators and is shown to match experimental values well. The model is used to explain the behaviour of the resonators in the regions where individual layers of the device themselves have thickness resonances at similar frequencies. It also demonstrates the importance of the bonding between layers and shows that the standing wave at a peak of the energy density response differs, in terms of nodal position and boundary impedance, from simple, rigid-rigid boundary models. The remainder of the thesis concentrates on the design and use of micro-scale devices in which the scale of the layers is similar to or smaller than the wavelengths in use. A novel microfabricated filtration device is described which is primarily constructed using silicon and Pyrex. The modelling, design, fabrication and initial testing of the device are discussed. An expanded version of the electro-acoustic model allows prediction of the radiation forces on an example particle within a standing wave field. This is used to examine the force profile on a particle at resonances with pressure nodes at different positions. An analytical method for predicting modal conditions for combinations of frequencies and layer thickness characteristics is presented, which predicts that resonances can exist that will produce a pressure node at arbitrary positions in the fluid layer of such a system. The model also predicts conditions for multiple sub-wavelength resonances within the fluid layer of a single resonator, each resonance having different nodal planes for particle concentration. This forms the basis for the design of a unique microfabricated resonator with several modes that allow particles to be forced to either boundary of the fluid or to the fluid centre, depending on the operating frequency.
2
Dobson, Corrine. "Manipulation of Starch Digestibility in Particle Form." Thesis, Université d'Ottawa / University of Ottawa, 2019. http://hdl.handle.net/10393/39794.
Full textAbstract:
This work investigates ways to prevent and manage hyperglycemia using preventive nutrition. Uncontrolled and chronic hyperglycemia is a global health issue leading to many health problems including diabetes. This thesis details the manipulation of highly retrograded starch particles in order to produce particles that are digested slowly to release glucose at a prolonged and moderate rate to prevent this. The first section of this study utilized acid hydrolysis to alter starch structure and change digestibility. The hydrolysis treatment showed that hydrolysis of native starch prior to particle formation changed the structure in a way that increased digestibility. The second section of this work introduced polyphenols into the particles which only a marginal effect on digestion. Overall the actual process of retrograding and making the particles themselves appeared to create particles that were more resistant to digestion. These could be used in a product to deliver a moderate glycemic response.
3
Wang, Han. "Development of electronic systems for ultrasonic particle manipulation." Thesis, University of Dundee, 2015. https://discovery.dundee.ac.uk/en/studentTheses/2bf4c7d2-a766-4720-88da-867412bb9274.
Full textAbstract:
Demands to handle individual particles or particle agglomerates have been emerging in the fields of biology and chemistry, and particle trapping and manipulation with mechanical waves generated from ultrasound sources, known as “acoustic tweezing”, has gained great interest by researchers and been proved useful for its unique advantages. With an analogy to optical tweezing, research has demonstrated the possibility to use modulated acoustic fields generated by ultrasound arrays for trapping individual particles and groups of particles at length scales from hundreds of µm to a few mm. This thesis explores and demonstrates particle trapping and manipulation with electronically-controlled miniaturized ultrasound arrays (element pitch around 500 µm or less), focusing on the development of dexterous electronic systems. Generally, in acoustic manipulation applications, low voltage outputs with continuous mode operation are required to create stable acoustic energy potential “landscapes” for trapping without damaging particles or cells. The research work of this thesis is oriented towards integration of control electronics with miniaturized ultrasound arrays. Test fixtures have been carefully designed and fabricated for the characterization of transducer arrays developed by collaborating researchers and array-controlled particle manipulation experiments have been demonstrated with customized fluorescence microscopy equipment. Most importantly, this thesis has established two versions of prototype Field programmable gate array (FPGA) based electronics to drive ultrasound arrays. One is a computer-controlled 16-channel system, with adjustable output frequencies, phases and amplitudes. Another is a 40-channel switching electronics for manual controlled output switching or time-shared output multiplexing. The electronic systems that have been developed are highly scalable and easily adapted for different acoustic tweezing applications. In conclusion, this thesis has proposed prototype electronic toolkits as research platforms to explore diverse possibilities for acoustic tweezing with miniaturized ultrasound arrays.
4
Rojas, Andrea Diane. "Particle Manipulation Using Electric Field Gradients in Microdevices." Thesis, Virginia Tech, 2012. http://hdl.handle.net/10919/41128.
Full textAbstract:
Electrokinetics is a family of effects that induces motion of a liquid or a particle within a liquid in response to an external electric field. Using the intrinsic electrical properties of bacteria and of breast cancer cells, electrokinetics can be used to manipulate these particles for two different types of applications: tissue engineering and breast cancer detection. The first application studied the effects of electric fields on bacteria cells as well as calcium ions to potentially create a meniscus scaffold with hydroxyapatite ends for anchoring. In response to the electric field, calcium ions were able to deposit locally and simultaneously with cellulose growth. Bacteria cells were also studied to determine their response under an AC field. At low frequencies, bacteria demonstrated controlled movement caused by electroosmosis and dielectrophoresis with a net motion caused by a dielectrophoretic force.
In the second application, the separation capabilities of different stages of breast cancer cells from the same cell line were tested using contactless dielectrophoretic (cDEP) devices. The electric field gradients in cDEP devices were altered to optimize selectivity and to determine an estimated membrane capacitance for each. From the results, the membrane capacitance of the early to intermediate stages proved to be very similar; however, late stage breast cancer cells have potential in being separated from early and intermediate stages.<br>Master of Science
5
Sinha, Ashok. "Characterizing Magnetic Particle Transport for Microfluidic Applications." Diss., Virginia Tech, 2008. http://hdl.handle.net/10919/29266.
Full textAbstract:
Magnetic particles with active functional groups offer numerous advantages for use in μ-TAS (Micro Total Analytical Systems). The functional site allows chemical binding of the particle with the target species in the fluid sample. Selection of the functional group establishes the target molecule and vice versa under assumptions of highly specific biding. The particles hence act as mobile reaction substrates with high surface to volume ratios owing to their small size. The concept of action at a distance allows their use as agents for separation in microchannels based on relatively simple design. It is possible to manipulate magnetic particles and bound target species using an externally applied magnetic field. Hence, the particles can be effectively separated from the flow of a carrier fluid. Magnetic fields create dipolar interactions causing the particles to form interesting structures and aggregates. Depending upon the applied field, the microstructure evolution of the aggregate is interesting in its own right, e.g. related to improvements in material properties and bottom-up self assembly. The shape of the aggregates can be determined a priori if the interaction between the particles is well characterized. The dominant competing forces that influence magnetic particle dynamics in a flow are magnetic and viscous. There are a number of physical parameters such as viscosity, magnetic susceptibility, fluid velocity, etc. which are varied to study their individual effects.
Initially dilute suspensions are studied experimentally and numerically using a particle based dynamics approach. Once established, a force model for particle interaction is investigated for concentrated suspensions. A Lagrangian particle tracking algorithm that returns positions of the particles is used for this work that focuses on studying the dynamics of these particles. A mathematical model is proposed and investigated for functionalization between magnetic and non-magnetic particles. Having characterized the collection of magnetic particles, the effect of relative concentrations is investigated on the collection of the non-magnetic species.<br>Ph. D.
6
Perfetti, Claire. "Particle manipulation in minichannels for enhanced digital holographic microscopy observation." Doctoral thesis, Universite Libre de Bruxelles, 2014. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/209283.
Full textAbstract:
The development of techniques targeting the manipulation of particles of different<p>sizes - mostly in the nano to millimeter scale - when dispersed in a carrier medium, is an increasingly important topic in many fields such as biotechnology,nanotechnology, medicine, biophysics and environmental monitoring and remediation. The underlying rationale for using such techniques stands in the sometimes compelling requirements of avoiding clogging as in micro/nano channel flows, of limiting sedimentation and wall interactions in particle/cell counting, of enhancing particle-surface interaction as in bio-sensing or of facilitating characterization and sorting as in bio-physical applications. Being developed in the frame of a Belgian national project devoted to the characterization and counting of pollutant in water media by digital holographic microscopy, this thesis tackles a peculiar class of particle manipulation techniques, commonly known as Focusing. The main goal of focusing is to avoid at best wall particle interactions and sedimentation, prevalent issues for dispersions owing in micro/mini-channels especially for applications such as optical characterization and counting.<p><p>The main attention was given to two flow focusing techniques - Hydrodynamic and Acoustic Focusing - for their wide range applicability and cost effectiveness. Hydrodynamic Focusing consists in controlling the position and spreading of the sample under investigation by means of a so-called sheath flow. A low-cost, nevertheless effective, prototype has been conceived, designed, manufactured and tested. It allowed for controlling the spreading of the sample stream and achieving a focusing ratio accounting for only 4% of the original stream width.<p><p>Acoustic Focusing takes advantage of the time-averaged pressure fields induced by the creation of standing waves in channels to manipulate and focus the dispersed particles. In the frame of this thesis, several devices have been developed using square cross section glass mini-channels. Aside from the cost-effectiveness, particles where focused in a somehow unexpected but high reproducible 3D matrix-like structure. A novel numerical model has also been implemented in order to study the conditions leading to the 3D structure formation. A good agreement between experimental and numerical results was found./Ce projet de thèse portant sur la manipulation de micro-particules dans des minicanaux s'inscrit dans le développement de cellules de flux pour des applications biologiques, qui est l'une des problématiques du projet HOLOFLOW, soutenu par<p>la région de Bruxelles Capitale. Les cellules de flux doivent permettre l'observation et la reconnaissance des micro-organismes vivants dans une large gamme de dimensions (de quelques microns à 1mm) avec la microscopie holographie digitale.<p>La problématique d'observation et de manipulation des microorganismes en flux est liée au clogging (bouchage) et à la sédimentation qui limitent la durée de vie des cellules d'observation. Ce projet de thèse s'inscrit dans cette problématique et propose deux axes d'étude pour limiter l'interaction entre organismes et canaux, la focalisation hydrodynamique, basée sur le guidage de flux, et la focalisation acoustique, basée sur la manipulation des particules.<p><p>La focalisation hydrodynamique est une technique basée sur l'injection différentiée de l'échantillon à observer et d'un fluide support. La différence des vitesses d'injection des flux permet de contrôler la dispersion des particules afin d'optimiser leur observation. Dans le cadre de cette thèse, un prototype à bas-coût a été développé et construit, permettant de focaliser les particules dans un faisceau jusqu'à 4% de leur faisceau incident.<p><p>La focalisation acoustique utilise la création d'une onde acoustique stationnaire afin de regrouper les particules en suspension au centre du canal. Au cours de cette thèse, plusieurs prototypes ont été réalisés, mettant en évidence la formation de motifs tridimensionnaux. Un model numérique a été spécialement développé afin d'étudier les conditions de génération de ces motifs, et de nombreuses expériences ont été menées afin de s'assurer de leur reproductibilité. Une bonne adéquation entre la position des particules mesurée et calculée numériquement a été démontrée.<br>Doctorat en Sciences de l'ingénieur<br>info:eu-repo/semantics/nonPublished
7
Jiang, Ke. "Particle manipulation in plasma device & Dynamics of binary complex plasma." Diss., lmu, 2011. http://nbn-resolving.de/urn:nbn:de:bvb:19-133463.
Full text
8
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.
Full textAbstract:
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.
9
Milne, Graham. "Optical sorting and manipulation of microscopic particles." Thesis, St Andrews, 2007. http://hdl.handle.net/10023/334.
Full text
10
Møller, Morten. "Optimizing the structure of scanning probes for atomic manipulation." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/44916/.
Full textAbstract:
Scanning probe microscopy (SPM) allows us to directly measure the interactions between a probe and a sample at the atomic scale. Techniques such as non-contact atomic force microscopy (NC-AFM), allows us to to characterize the forces present on a surface, resolve the atomic structure of molecules or examine their chemical properties, while scanning tunneling microscopy (STM) allows their electronic properties to be characterized. As the interactions take place at the atomic scale, the atomistic state of the probe apex plays a crucial role. In AFM, it is the atomic scale forces between the outermost atoms of the probe and surface that are dominant, while for STM the density of states (DOS) that contribute to tunneling are crucial. Therefore, understanding and controlling the tip termination is crucial to derive meaningful interpretations from experimental data. In this thesis, the role of the tip termination is examined for various surfaces and situations. We find that determining the "right" tip state depends critically on the experiment and several general strategies for shaping the tip apex into a preferred state are therefore outlined. H:Si(100) surfaces were used as a substrate for lithographic patterning using STM. We have successfully implemented an automated extraction routine for performing large scale patterning with high fidelity and single atom specificity. Our ultimate goal is to combine the extraction routine with SPM image recognition software to allow analysis and manipulation of atomic scale features without human intervention. To perform manipulations reliably, the tip influence on "what we see" (tip imaging states), or specifically on what the recognition software can identify, needs to be considered. We find, counter-intuitively, that atomic scale manipulation with the highest fidelity occurs when silicon dimers are observed as rows as opposed to when atomic resolution imaging occurs. The tip state influence on measuring surface diffusion of PTCDA on Ag(110) surfaces, was also investigated. We find that the adsorption kinetics of diffusing molecules can only be detected for specific tip imaging states. To allow examination with no-human intervention, the tip state needs to be carefully considered, and a combination of analytical and spectroscopic tools needs to be implemented in conjunction with the experiment. Additionally, characterization of the tip apex was investigated at the tunnel junction between a STM tip and a metal surface using field emission measurements. Our results suggest that field emission measurements performed at the tunnel junction are sensitive to changes in the nanoscopic/mesoscopic tip apex structure, thus opening up the possibility of automating the process of characterization the tip apex.
11
Shah, Gaurav Jitendra. "Electrowetting-on-dielectric (EWOD) for biochemical applications particle manipulation for separation in droplet microfluidics /." Diss., Restricted to subscribing institutions, 2008. http://proquest.umi.com/pqdweb?did=1779690391&sid=5&Fmt=2&clientId=48051&RQT=309&VName=PQD.
Full text
12
Lei, Junjun. "An investigation of boundary-driven streaming in acoustofluidic systems for particle and cell manipulation." Thesis, University of Southampton, 2015. https://eprints.soton.ac.uk/384748/.
Full text
13
Paul, Alison Marie. "Design and optimization of efficient microfluidic platforms for particle manipulation and cell stimulation in systems biology." Diss., Georgia Institute of Technology, 2011. http://hdl.handle.net/1853/45818.
Full textAbstract:
The overall goal of this research was to develop an efficient microfluidic system to study signal transduction in stimulation dynamics. This research applied reactive transport fundamentals in concert with biological systems knowledge to completely understand diffusion of soluble signals, fluid and particle flow properties, and dynamics of cellular responses. First, a device capable of parallel multi-time-point cell stimulation and lysis on-chip was developed in collaboration. Second, to understand flow of cells through complex 3-D flow schemes, a Single-field Three-dimensional Epifluorescence Particle (STEP) imaging technique was developed. Using the STEP imaging technique, we were able to determine particle distributions and track individual particles in complex flow geometries. Third, during the design of the stimulation device it was observed that the cells do not distribute across the channel in the same way as the fluids. Based on the observation that geometry and particle size were most influential factors on particle distribution, it was hypothesized that our earlier observation and all observed phenomena in our experimental range were due to the volume exclusion of particles of finite size near the wall of the complex flow geometry. Overall, this work contributed to the realization of microfluidic platforms as powerful tools for probing areas of biology and medicine that are difficult with existing technology. The high-throughput format enabled simple and fast generation of large sets of quantitative data, with consistent sample handling. We demonstrated the necessary first steps to designing efficient unit operations on cells in microfluidic devices. The model can be used for informed design of unit operations in many applications in the future.
14
Vieira, Gregory Butler. "Patterned Magnetic Structures for Micro-/Nanoparticle and Cell Manipulation." The Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1354567338.
Full text
15
Gherardi, David Mark. "Studies of particle and atom manipulation using free space light beams and photonic crystal fibres." Thesis, St Andrews, 2009. http://hdl.handle.net/10023/703.
Full text
16
Melde, Kai [Verfasser], and J. [Akademischer Betreuer] Korvink. "The Acoustic Hologram and Particle Manipulation with Structured Acoustic Fields / Kai Melde ; Betreuer: J. Korvink." Karlsruhe : KIT Scientific Publishing, 2019. http://d-nb.info/1202112080/34.
Full text
17
Jiang, Ke [Verfasser], and Gregor Eugen [Akademischer Betreuer] Morfill. "Particle manipulation in plasma device & Dynamics of binary complex plasma / Ke Jiang. Betreuer: Gregor Eugen Morfill." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2011. http://d-nb.info/1015169791/34.
Full text
18
Kuhlicke, Alexander. "Electromagnetic Manipulation of Individual Nano- and Microparticles." Doctoral thesis, Humboldt-Universität zu Berlin, 2017. http://dx.doi.org/10.18452/18554.
Full textAbstract:
Gegenstand der vorliegenden Dissertation ist die Untersuchung von einzelnen nano- und mikrometergroßen Partikeln, zum Verständnis und zur Entwicklung von neuartigen nanooptischen Elementen, wie Lichtquellen und Sensoren, sowie Strukturen zum Aufsammeln und Leiten von Licht. Neben der Charakterisierung stehen dabei verschiedene Methoden zur elektromagnetischen Manipulation im Vordergrund, die auf eine Kontrolle der Position oder der Geometrie der Partikel ausgerichtet sind. Die gezielten Manipulationen werden verwendet, um vorausgewählte Partikel zu isolieren, modifizieren und transferieren. Dadurch können Partikel zu komplexeren photonischen Systemen kombiniert werden, welche die Funktionalität der einzelnen Bestandteile übertreffen. Der Hauptteil der Arbeit behandelt Experimente mit freischwebenden Partikeln in linearen Paul-Fallen. Durch die räumliche Isolation im elektrodynamischen Quadrupolfeld können Partikel mit reduzierter Wechselwirkung untersucht werden. Neben der spektroskopischen Charakterisierung von optisch aktiven Partikeln (farbstoffdotierte Polystyrol-Nanokügelchen, Cluster aus Nanodiamanten mit Stickstoff-Fehlstellen-Zentren, Cluster aus kolloidalen Quantenpunkten) sowie optischen Resonatoren (plasmonische Silber-Nanodrähte, sphärische Siliziumdioxid-Mikroresonatoren) werden neu entwickelte Methoden zur Manipulation vorgestellt, mit denen sich individuelle Partikel freischwebend kombinieren und elektromagnetisch koppeln sowie aus der Falle auf optischen Fasern zur weiteren Untersuchung bzw. zur Funktionalisierung photonischer Strukturen ablegen lassen. In einem weiteren Teil der Arbeit wird eine Methode zur Manipulation der Geometrie von plasmonischen Nanopartikeln vorgestellt. Dabei werden einzelne Goldkugeln auf einem Deckglas mit einem fokussierten Laserstrahl zum Schmelzen gebracht und verformt. Durch die kontrollierte und reversible Veränderung der Symmetrie lassen sich die lokalisierten Oberflächenplasmonen des Partikels gezielt beeinflußen.<br>The topic of the present thesis is the investigation of single nano- and microsized particles for the understanding and design of novel nanooptical elements as light sources and sensors, as well as light collecting and guiding structures. In addition to particle characterization, the focus is on different methods for electromagnetic particle manipulation aimed at controlling the particle’s position or geometry. The specific manipulations are used for isolation, modification and transfer of preselected particles, enabling combination of particles into more complex photonic systems, which exceed the functionalities of the individual constituents. The main part of this work deals with experiments on levitated particles in linear Paul traps. Due to the spatial isolation in the electrodynamic quadrupole field, particles can be investigated with reduced environmental interaction. In addition to spectroscopic characterization of optically active particles (dye-doped polystyrene nanobeads, clusters of nanodiamonds with nitrogen vacancy defect centers, clusters of colloidal quantum dots) and particles with optical resonances (plasmonic silver nanowires, spherical silica microresonators) new manipulation methods are presented that enable assembly and electromagnetic coupling of individual, levitated particles as well as deposition of particles from the trap on optical fibers for further characterization or functionalization of photonic structures. In a further part of this work a method to manipulate the geometry of plasmonic nanoparticles is presented. Single gold nanospheres on a coverslip are melted and shaped with a focused laser beam. The localized surface plasmons can be influenced specifically by controlled and reversible changes of the particle symmetry.
19
Paulk, Chad Bennett. "Manipulation of processing technologies to enhance growth performance and (or) reduce production costs in pigs." Thesis, Kansas State University, 2011. http://hdl.handle.net/2097/9206.
Full textAbstract:
Master of Science<br>Department of Animal Sciences and Industry<br>Joe D. Hancock<br>Nine experiments were completed to evaluate the effects of feed manufacturing practices on milling characteristics of diets and growth performance and stomach morphology in pigs. In Exp. 1 and 2, reducing the particle size of sorghum from 800 to 400 μm improved (P < 0.04) efficiency of gain in finishing pigs by 5% but had negative effects on cost of milling and stomach morphology. In Exp. 3 and 4, finishing pigs fed diets with 10 mg/kg of ractopamine HCl, had improved (P < 0.05) ADG, G:F, HCW, dressing percentage, and percentage carcass lean. However, increasing mix time of the diet from 0 to 360 s did not affect (P > 0.06) the response of finishing pigs to ractopamine HCl. In Exp. 5 and 6, adding ground and cracked corn to a pelleted supplement for nursery pigs decreased (P < 0.01) growth performance compared to feeding a complete pellet. In Exp. 7, increasing the percentage of cracked corn in a diet for finishing pigs decreased development of stomach lesions but also had a generally negative effect on efficiency of gain. In Exp. 8, adding cracked corn to a pelleted supplement (as done for the nursery pigs) decreased milling costs and improved health of stomach tissue. But, G:F was decreased by 6% (P < 0.05) which will make this technology unattractive to swine producers. In our final experiment (Exp. 9), pigs fed pellets tended to have the greatest growth performance, pigs fed mash the worst, and pigs fed pellets for only part of the grow-finish phase fell in between. In conclusion, grinding sorghum-based diets for finishing pigs improved efficiency of growth but extensive mixing to maximize diet uniformity had no effect on growth performance or carcass measurements. Use of cracked corn in diets does decrease diet costs and improve stomach health in finishing pigs but feeding of complete pellets for the entire finishing period supports maximum rate and (or) efficiency of gain.
20
Kuznetsov, Volodymyr [Verfasser], and Georg [Akademischer Betreuer] Papastavrou. "Direct Force Measurements on the Colloidal Scale: From Modified Electrodes to Particle Manipulation / Volodymyr Kuznetsov. Betreuer: Georg Papastavrou." Bayreuth : Universität Bayreuth, 2013. http://d-nb.info/1059352966/34.
Full text
21
Castro, Angelica. "Manipulation of biomimetic objects in acoustic levitation." Phd thesis, Université Pierre et Marie Curie - Paris VI, 2013. http://pastel.archives-ouvertes.fr/pastel-00938546.
Full textAbstract:
La lévitation acoustique par des ondes stationnaires ultrasonores (USW), permettent la manipulation des objets micrométriques. L'objectif principal de cette thèse est d'explorer les possibilités offertes par la lévitation acoustique pour manipuler des particules, des cellules et même des bactéries. Nous avons conçu et construit tous les résonateurs et nous avons développé les méthodologies que nous allons montrer dans ce travail expérimental. Selon la nature des particules, leur déplacement est donné par son interaction avec la force acoustique primaire. La position où les particules se déplacent est le point dont les forces acoustique et gravitationnel sont équilibrées. Dans le plan de lévitation, les interactions connues comme force secondaire de Bjerknes est la première étape du processus d'agrégation. Nous présentons une méthodologie pour mesurer cette force. Nous avons mesuré cette force en conditions de micropesanteur. Dans nous résonateurs, nous travaillons avec un grand nombre des particules dont les agrégats sont 3D. Nous introduisons le mode acoustique pulsé que nous permet générer des agrégats 2D. Lorsque les particules deviennent plus petites de 1µm, sa manipulation est difficile en raison de l'influence de l'acoustic streaming qui modifie le comportement des particules. Le mode acoustique pulsé permet de réduire ou de contrôler l'acoustic streaming que nous permet manipuler des particules de taille submicronique, des bactéries et des micro-cylindres catalytiques. Une séparation a été faite par un mélange des particules de 7-12µm dans le dispositif s-SPLITT. Néanmoins la combinaison de forces hydrodynamique et acoustique (HACS) a permis améliorer la séparation.
22
Bernard, Ianis. "Manipulation de particules et génération de vortex par ondes acoustiques de surface en géométrie microfluidique." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAY015/document.
Full textAbstract:
Dans cette thèse, nous nous sommes intéressés à la manipulation par forces acoustiques de particules et de fluide à petite échelle. Nous avons construit pour cela un système où des ondes acoustiques de surface sont générées sur un substrat piézo-électrique de LiNbO3 à partir d’électrodes interdigitées, puis émises dans une cavité microfluidique, à une fréquence de l’ordre de 37 MHz soient des longueurs d’onde d'environ 100 µm.Dans le cas où deux ondes stationnaires sont émises perpendiculairement et à la même fréquence, nous montrons théoriquement et expérimentalement la présence d’un terme d’interférence qui, selon le déphasage temporel entre les deux ondes, va modifier la localisation des ventres et nœuds de pression dans la cavité, mais aussi donner lieu à des tourbillons dont l’axe de rotation est perpendiculaire au substrat.Nous montrons théoriquement que ces tourbillons proviennent de la forme particulière des écoulements redressés en paroi et, en injectant des microparticules, nous avons déterminé des vitesses angulaire de plusieurs rad/s. Leur disposition spatiale suit une périodicité d'une demi-longueur d'onde, et leur sens de rotation est alternée entre tourbillons voisins horaires et anti-horaires. Que cela soit avec des globules rouges ou des particules de latex, nous avons identifié une dynamique complexe, avec la formation d’agrégats au centre des vortex sous l’effet des forces de radiations et une répartition en différents niveaux par effet de lévitation acoustique dans l’épaisseur de la cavité, en accord avec l'analyse.Dans le cas où des particules d’une dizaine de micromètres sont utilisées, nous observons, outre l’arrangement des objets dans les nœuds de pression, une rotation individuelle de chaque objet, à des vitesses angulaires plus élevées. Nous interprétons ces observations comme la première mise en évidence d’un couple d’origine acoustique sur des microparticules et cellules biologiques à partir d’ondes acoustiques de surface, constituant l’analogue à petite échelle des effets de couples acoustiques décrits par Busse et Wang en 1981.La thèse propose une description détaillée des différentes montages électriques et microfluidiques, avec les différentes étapes conduisant à un laboratoire sur puce permettant la génération tant de forces que de couples acoustiques, mais aussi la manière de qualifier électriquement et optiquement ses performances<br>The focus of this PhD thesis was on particles and fluid handling through acoustic forces, at a very small scale. For this purpose, we built a micro-system based on surface acoustic waves emitted from interdigitated electrodes on a lithium niobate piezoelectric substrate. Those waves then leak into a fluid contained in a microfluidic cavity, at a frequency of 37 MHz, leading to 100 µm wavelengths.If two stationnary waves are emitted perpendicularly and at the same frequency, we theoretically and experimentally show evidence of interferences that can, depending on the time phase shift between them, nto only alter the positions of pressure nodes and antinodes in the acoustic cavity, but also give birth to acoustic vortices which axis is normal to the substrate surface.We theoretically show that those vortices come from the special behaviour of acoustic streaming due to a moving surface. Then, while injecting microparticles in the cavity, we measure angular velocities of a few rad/s. Those vortices spatial disposition follows a half-wavelength period, and their rotation alternates between neighbours: clockwise or anticlockwise. We identify a complex dynamic concerning their 3D structure, since small particles tend to aggregate in vertical columns in the center of the vortex because of radiation forces, with a vertical modulation in the height of the cavity, in good agreement with theoretical predictions.When 10 µm large particles are used instead, we observe individual rotations, even for spherical objects, with higher rotation velocities. We believe those observations to be the first evidence of an acoustic net torque exerted on micro-objects such as biological cells or beads stemming from surface acoustic waves, thus a small scale equivalent of acoustic torques described by Busse and Wang in 1981.This manuscript develops a detailed description of both electric and microfuidic devices, giving the successive steps leading to a lab on chip designed to generate acoustic forces and torques at once, and also the method for qualifying and quantifying electrically and optically its performances
23
Söderbäck, Per. "Micromachining of microfluidicsystems using a nanosecond laser : Process optimization and application." Thesis, Uppsala universitet, Mikrosystemteknik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-402248.
Full textAbstract:
Microfluidics is a field of research that enables the manipulation of fluids in the submillimetre length scale. The technology allows the development of lab-on-a-chip devices, which are miniaturized systems for chemical and biological analysis. Currently, the conventional manufacturing methods for these systems require multiple time-consuming steps. Therefore, focus has shifted towards laser micromachining as an alternative method. Direct laser writing would circumvent many of the steps required for the conventional methods, drastically reducing the process time. In this Master thesis project, it was shown that microfluidic chips can be manufactured using a Nd:YVO4 (532 nm) nanosecond laser system. The process was optimized for silicon and borosilicate glass substrates. Acoustic focusing of polystyrene beads was demonstrated for a system etched in silicon. The optimized process used a power of 50%, a frequency of 10 kHz, a scan speed of 60 mm/s with triple lines as fill type and it had an etch rate of 4.3 μm/pass. Processed wafers were cleaned in buffered HF and bonded using anodic bonding as well as adhesive bonding. Processing of glass proved unpredictable, resulting in cracks and chippings. However, in- and outlets were successfully etched through thin glass wafers. It was found that crucial factors for the process were to control the focus, positioning of structures, structure orientation and the pulse separation for a uniform distribution of pulses. Based on the results, it is estimated that the manufacturing process could be done in two to three days using the laser micromachining process.
24
Leuthner, Moritz. "Improving cell secretome analysis and bacteria evolution by means of acoustophoresis." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-285985.
Full textAbstract:
In both, cell secretome analysis and bacteria evolution, controlled handling of particles with a few to sub-micrometers in size and media exchange are inevitable in order to investigate body fluid’s proteins or change the surrounding culture conditions for pivoted evolution. Typically, nanofiltration and ultra-centrifugation are employed which can lead to cell damage, need large sample volumes and have a high sample loss. Using contactless and label-free acoustic cell manipulation, disadvantages of other magnetic, dielectric or hydrodynamic methods can be avoided. Here, a novel design using acoustic forces for small particle trapping and media exchange is thoroughly numerically investigated including first- and second-order acoustic effects. The device comprises parallel aligned medium and air channels separated by a thin wall. Particle trapping occurs at this thin wall. The medium channel dimensions (height and width) and thin wall thickness are optimized with respect to trapping forces. Thinnest walls are preferable and an aspect ratio of 0.8. First preliminary experimental variation with polystyrene particles showed good agreement with the simulations. Thereby the particle trapping efficiency is evaluated under quiescent flow conditions. For particle trapping, a device with a channel height of 290μm and an aspect ratio of 0.7 is superior which supports the numerical results. Finally, medium exchange of E. coli bacteria is demonstrated with best results for a device with a channel height of 450μm and an aspect ratio of 0.8 showing that 13.4% of the initial bacteria were released after medium exchange which can be used for further processing.
25
Shen, Z. "Optical manipulation of metallic particles." Thesis, University of Liverpool, 2017. http://livrepository.liverpool.ac.uk/3008095/.
Full textAbstract:
Plasmonic tweezers and optical tweezers are two techniques for trapping and manipulating particles. Plasmonic tweezers utilizes localized surface plasmon field, whilst optical tweezers utilizes focused laser beam. In this thesis, these two techniques were applied for the manipulation of metallic particles in three basic forms: single particle, particle dimer and particle trimer. Firstly, the trapping of metallic particles was investigated through focused plasmonic tweezers when surface plasmons are excited by focused Radially Polarized Beam (RPB). The force exerted on the metallic particle is responsible for the trapping, which is found to be due to the sum of both gradient and scattering forces acting in the same direction established by the coupling between the metallic particle and focused plasmonic field. This contrasts the repulsion of metallic particles in optical tweezers. Focused plasmonic trapping of metallic particle enables actively moving metallic particle in a controlled way, which could be used for intracellular Surface Enhanced Raman Scattering (SERS) imaging. Secondly, the trapping of horizontally-oriented metallic particle dimers was theoretically studied through focused plasmonic tweezers when surface plasmons are excited by focused linearly-polarized beam. It was found that a Surface Plasmon Virtual Probe (SP-VP) pair was generated on a metal film. A formula is derived to represent the electric field of SP-VP pair, revealing that the spacing of the two virtual probes is wavelength-dependent. Each SP-VP is able to trap a metallic particle, thus the gap between the trapped particles of the dimer can be controlled by changing the excitation wavelength. This theory was further tested by successfully trapping nanosphere and nanorod metallic dimers with 10 nm gaps. The trapped dimer showed a typical electric field enhancement of more than 103 times, which is enough for single molecule SERS detection. Thirdly, a vertically-oriented dimer structure was proposed based on trapping of metallic nanoparticle by focused plasmonic tweezers. The vertically-oriented dimer can effectively make use of the dominant longitudinal component of the SP-VP thus providing much stronger electric field in the gap. Furthermore, for practical application the top nanoparticle of the dimer can be replaced with the tip of an atomic force microscope which enables the precise control of the gap distance of the dimer. Therefore the proposed vertically-oriented dimer structure provides both the scanning capability and the extremely-high electric field enhancement necessary for the high sensitivity Raman imaging. Lastly, the stable trapping and steady rotation of a metallic particle trimer were experimentally achieved by optical tweezers with optical vortex. The trimer particles are found to be confined inside the maximum intensity ring of a focused circularly polarized optical vortex. Theoretical analysis suggests that a large proportion of the radial scattering force pushes the particles together, whilst the remaining portion provides the centripetal force necessary for the rotation. The achieved steady rotation of the metallic particle trimer may lead to the development of microfluidics devices such as micro-rotor.
26
Pritchard, Claire Halina. "Manipulation of carrier particles for inhalation." Thesis, De Montfort University, 2003. http://hdl.handle.net/2086/10676.
Full textAbstract:
The work described in this thesis was performed to investigate the effect of altering the conditions of recrystallisation for selected sugars and sugar derivatives (lactose, trehalose dihydrate and trehalose octa-acetate (TOAc» in order to assess the physical effect on the material surface. In addition to recrystallised materials, amorphous materials were also produced. The short-acting betas- agonist, salbutamol sulphate, was subsequently used to assess the relative performance of these materials as drug carriers in a dry powder inhaler (OPI). The main aim of the research was to establish whether a relationship exists between the surface characteristics of a material and the performance of the material as a drug carrier in a OP!. A fundamental part of the research involved the physiochemical characterisation of the sugars, including solubility determinations for trehalose and TOAc in a range of ethanol:water solvents. Following recrystallisation, considerable time had to be spent in order to confirm the identity of the recrystallised TOAc material, as initial analysis was not conclusive in determining that the material had remained chemically unchanged following recrystallisation. Optimisation of drying of the TOAc material following recrystallisation was also performed, and X-ray crystallography of samples of the TOAc material suggested that it exists in at least three different crystalline forms. Characterisation of the surface roughness using laser profilometry was performed before the materials (sieved to obtain a particle size range of 63 - 90 J.U1l) were blended with salbutamol sulphate (micronised to a particle size of 5 J.U1l). A multi-stage liquid impinger (MSLI) was used to quantify in vitro the performance of each material as a drug carrier from the OPI device - FlowCaps® (Hovione). Overall, the results indicated that the surface roughness values (R.) required to achieve the optimum performance as a drug carrier were in the range of 1.9 to 2.7 J.U1l. Inaddition, when considering the hydrophilic or hydrophobic nature of the sugars assessed, a trend appeared to exist. The results indicated an optimum R. in the range of 1.9 to 2.3 J.U1l for materials that exhibited hydrophobic characteristics, and a range of 2.1 to 2.7 J..UD for materials that were considered hydrophilic. Inconclusion, the results obtained indicate that a relationship between the surface characteristics of a material and its performance as a drug carrier in a OPI does exist, but that the optimum relationship is determined by a number of factors. Inaddition to the surface characteristics, the physiochemical properties of the carrier material and the active drug together with the characteristics of the chosen OPI device itself, all contribute to the relationship that determines performance.
27
Ng, Li Na. "Manipulation of particles on optical waveguides." Thesis, University of Southampton, 2000. https://eprints.soton.ac.uk/15499/.
Full textAbstract:
A theoretical and experimental study on the optical trapping and propulsion of latex, gold aggregate and colloidal gold particles with average radius of 1.5µm, 250nm and 10nm respectively, in the evanescent region of an illuminated ion-exchange channel waveguide is documented in this thesis. Optimisation of light-induced forces exerted on a particle on a waveguide relies on two important factors, firstly a maximisation of the intensity and intensity gradient present in the guide-cover interface and secondly, an optimisation of the polarizability of a particle. To this end, a transcendental equation was established and was used to generate design curves for the normalised waveguide thickness required for achieving a maximum gradient force on the guide-cover interface of a waveguide for a specific set of indices. A study based on Mie theory for the investigation of morphology dependent resonance exhibited by a spherical particle is described. The dependence of resonances on particle radius, index of the sphere with respect to the surrounding medium, absorption, plasmon resonance and symmetry of the incident beam has been investigated. In particular, a simplification of the Mie model was carried out to derive Rayleigh expressions of cross sections from which particle polarizability originates. The validity of the Rayleigh model was assessed with respect to the limiting particle radius. Based on a semi-classical approach, a derivation of light-induced forces applying to a Rayleigh sphere in the cover region of a waveguide is detailed. The three main optical force components produced are (i) a forward scattering and absorption force due to the intensity of the incident radiation which accounts for propulsion of particles, (ii) a transverse gradient force due to an intensity gradient generated by a decaying evanescent field and finally (iii) a lateral gradient force which arises from the near-Gaussian intensity distribution on a channel waveguide. A comparison of the relative magnitude of each component is described, with additional forces due to gravity, buoyancy and Brownian motion studied. Factors affecting the propulsion of a gold nanoparticle were investigated. It was shown that the particle velocity is linearly dependent upon the waveguide modal power, increases with a wavelength closer to plasmon resonance in the case of a Rayleigh gold particle, is stronger for TM polarized light, increases with a larger change in the waveguide refractive index and is maximum for a minimum modesize. For the first time, under the action of light-induced forces generated on the surface of an optical waveguide, colloidal gold particles are propelled in the direction of wave propagation reaching at a maximum velocity of 10µm/s for a modal power of 500mW at l=1.047µm. Results obtained will be useful for future applications in particle sorting, fluorescence sensing and surface enhanced Raman sensing of chemical species.
28
Dienerowitz, Maria. "Plasmonic effects upon optical trapping of metal nanoparticles." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1634.
Full textAbstract:
Optical trapping of metal nanoparticles investigates phenomena at the interface of plasmonics and optical micromanipulation. This thesis combines ideas of optical properties of metals originating from solid state physics with force mechanism resulting from optical trapping. We explore the influence of the particle plasmon resonance of gold and silver nanospheres on their trapping properties. We aspire to predict the force mechanisms of resonant metal particles with sizes in the Mie regime, beyond the Rayleigh limit. Optical trapping of metal nanoparticles is still considered difficult, yet it provides an excellent tool to investigate their plasmonic properties away from any interface and offers opportunities to investigate interaction processes between light and nanoparticles. Due to their intrinsic plasmon resonance, metal nanoparticles show intriguing optical responses upon interaction with laser light. These differ greatly from the well-known bulk properties of the same material. A given metal nanoparticle may either be attracted or repelled by laser light, only depending on the wavelength of the latter. The optical forces acting on the particle depend directly on its polarisability and scattering cross section. These parameters vary drastically around the plasmon resonance and thus not only change the magnitude but also the direction and entire nature of the acting forces. We distinguish between red-detuned and blue-detuned trapping, that is using a trapping wavelength shorter or longer than the plasmon resonance of the particle. So far optical trapping of metal nanoparticles has focussed on a wavelength regime far from the particle’s resonance in the infrared. We experiment with laser wavelengths close to the plasmon resonance and expand the knowledge of metal nanoparticle trapping available to date. Existing theoretical models are put to the test when we compare these with our real experimental situations.
29
Hughes, Michael Pycraft. "Electrokinetic manipulation of particles : computer aided studies." Thesis, Bangor University, 1995. https://research.bangor.ac.uk/portal/en/theses/electrokinetic-manipulation-of-particles--computer-aided-studies(77d0cf41-088b-458e-89d2-c3262d0f6dd3).html.
Full text
30
Skotis, Georgios D. "Sonocytology : dynamic acoustic manipulation of particles and cells." Thesis, University of Glasgow, 2018. http://theses.gla.ac.uk/8787/.
Full textAbstract:
Separating and sorting cells and micro-organisms from a heterogeneous mixture is a fundamental step in biological, chemical and clinical studies, enabling regenerative medicine, stem cell research, clinical sample preparation and improved food safety. Particle and cell manipulation by ultrasound acoustic waves provides the capability of separation of cells on the basis of their size and physical properties. Offering the advantages of relatively large microfluidic volumes in a label-free, contactless and biocompatible manner. Consequently, the discovery of alternative methods for precise manipulation of cells and particles is of highly demand. This thesis describes a novel approach of ultrasound acoustic manipulation of particles and cells. The principle of operation of the dynamic acoustic field method is described accompanied with acoustic separation simulations. Furthermore, the complete fabrication and characterisation of two types of ultrasound devices is given. The first one is a bulk acoustic wave (BAW) device and the second is a surface acoustic wave (SAW) device. Successful experiments using the BAW device for sorting different diameter particles with a range from 5 to 45 μm are demonstrated, also experiments for sorting particles depending on their density are presented. Moreover, experiments of the proposed method for sorting porcine dorcal root ganglion (DRG) cells from a heterogeneous mixture of myelin debris depending on their size are displayed. Experimental results of sorting cells depending on their stiffness are demonstrated. Experiments using the fabricated SAW device for sorting different diameter particles in a constant flow with a range from 1 μm to 10 μm are presented. Furthermore, experiments of the proposed method for sorting live from dead Htert cells depending on their mechanical properties, i.e. stiffness are displayed. As a side project a new idea for dynamic acoustic manipulation by rotating the acoustic field is demonstrated. The basic principles of this method and the simulations for verifying this concept are displayed. Experiments for sorting 10 μm from 3 μm polystyrene particles are presented, with two different types of the dynamic acoustic rotating field being examined.
31
Johansson, Linda. "Acoustic Manipulation of Particles and Fluids in Microfluidic Systems." Doctoral thesis, Uppsala universitet, Mikrostrukturteknik, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-100758.
Full textAbstract:
The downscaling and integration of biomedical analyses onto a single chip offers several advantages in speed, cost, parallelism and de-centralization. Acoustic radiation forces are attractive to use in these applications since they are strong, long-range and gentle. Lab-on-a-chip operations such as cell trapping, particle fluorescence activated cell sorting, fluid mixing and particle sorting performed by acoustic radiation forces are exploited in this thesis. Two different platforms are designed, manufactured and evaluated.
32
Lock, Gary. "Novel dielectrophoretic techniques for the manipulation of bio-particles." Thesis, Bangor University, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.273664.
Full text
33
Rose, Klint A. "Microfluidic manipulation and detection methods for metal microbarcode particles /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
Full text
34
Renaut, Claude. "Nanopinces optiques sur puce pour la manipulation de particules diélectriques." Thesis, Dijon, 2014. http://www.theses.fr/2014DIJOS010/document.
Full textAbstract:
Les nanocavités optiques sur puces sont devenues aujourd'hui des objets de base pour le piégeage et la manipulation d'objets colloïdaux. Nous étudions dans cette thèse des nanocavités comme briques de bases du piégeage et de la manipulation par forces optiques. La preuve de concept du piégeage de microsphères diélectriques apparaît comme le point de départ de l'élaboration d'un laboratoire sur puce. Dans le premier chapitre nous parcourons la bibliographie de l'utilisation des forces optiques en espace libre et en milieu confiné pour le piégeage de particules. Le second chapitre présente les dispositifs expérimentaux pour la caractérisation des nanocavités et les outils mis en place pour les mesures optiques en présence de particules colloïdales. Le troisième chapitre explique la preuve de concept du piégeage de particules de polystyrène de 500 nm, 1 et 2 µm. Dans le chapitre qui suit nous analysons le piégeage de particules en fonction de la puissance injectée dans la cavité. Le chapitre cinq décrit quelques exemples des possibilités de fonctions de manipulation de particules grâce à des cavités couplées. Enfin, dans le dernier chapitre nous montrons les assemblages de particules sur les différents types de cavités étudiées dans cette thèse<br>On chips optical nanocavities have become useful tools for trapping and manipulation of colloidal objects. In this thesis we study the nanocavities as building blocks for optical forces, trapping and handling of particles. Proof of concept of trapping dielectric microspheres appears as the starting point of the development of lab on chip. In the first chapter we go through the literature of optical forces in free space and integrated optics. The second chapter presents the experimental tools for the characterization of nanocavities and the set-up developed to perform optical measurements with the colloidal particles. The third chapter describes the proof-of-concept trapping of polystyrene particles of 500 nm, 1 and 2 µm. In the following chapter we analyze the particle trapping as function of the injected power into the cavities. The chapter five gives some examples of the possibilities of particles handling functions with coupled cavities. Eventually, in the last chapter we show assemblies of particles on different geometry of cavities studied in this thesis
35
Chowdhury, Ovee Zaman. "Development of digital microfluidic device for dielectrophoretic manipulation of particles." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/44635.
Full textAbstract:
This thesis presents the development of a parallel plate lab-on-a-chip (LOC) device for manipulating biological/surrogate particles in droplet based digital microfluidic (DMF) platforms. A fundamental principle, known as dielectrophoresis (DEP), is used to manipulate the particles in a non-uniform electric field based on their polarizability. DEP can be observed as positive (pDEP) and negative (nDEP), moving particles toward the high and low intensity electric fields, respectively.
Binary separation of two particles (Polystyrene beads and E.coli) has been shown on DMF platform by combining pDEP and nDEP. Polystyrene beads are trapped along the edge due to pDEP whereas cultured E.coli is repelled away from the edges due to nDEP. Although capturing the particles using pDEP is easier, for most biological applications requiring a high conductivity buffer medium, nDEP traps must be used to preserve the physiological characteristics of the particle. This thesis also contains the study of developing nDEP traps on DMF devices. The relation between the nDEP traps and the particle size has been demonstrated based on experimental results. Characterization of these traps of two different shapes (circular and squared) results in defining lifting and trapping zones. This study also yields in optimizing the trap size for single particle immobilization which is important for cell printing and growth applications. The ratio of trapping zone to the total area has been presented with a limiting factor K, which is proposed as a parameter to define the maximum trapping zone. Design of experiment has been used as an additional tool to show the relationship between the trapping zone and the total trap.
36
Malnar, Branimir. "Numerical modeling of dielectrophoretic effect for manipulation of bio-particles." Thesis, Brunel University, 2009. http://bura.brunel.ac.uk/handle/2438/4502.
Full textAbstract:
This text describes different aspects of the design of a Doctor-on-a-Chip device. Doctor-on-a-Chip is a DNA analysis system integrated on a single chip, which should provide all of the advantages that stem from the system integration, such as small sample volume, fast and accurate analysis, and low cost. The text describes all of the steps of the on-chip sample analysis, including DNA extraction from the sample, purification, PCR amplification, novel dielectrophoretic sorting of the DNA molecules, and finally detection. The overview is given of the technologies which are available to make the integration on a single chip possible. The microfluidic technologies that are used to manipulate the sample and other chemical reagents are already known and in this text they are analyzed in terms of their feasibility in the on-chip system integration. These microfluidic technologies include, but are not limited to, microvalves, micromixers, micropumps, and chambers for PCR amplification. The novelty in the DNA analysis brought by Doctor-on-a-Chip is the way in which the different DNA molecules in the sample (for example, human and virus DNA) are sorted into different populations. This is done by means of dielectrophoresis – the force experienced by dielectric particles (such as DNA molecules) when subject to a non-uniform electric field. Different DNA molecules within a sample experience different dielectrophoretic forces within the same electric field, which makes their separation, and therefore detection, possible. In this text, the emphasis is put on numerical modelling of the dielectrophoretic effect on biological particles. The importance of numerical modelling lies in the fact that with the accurate model it is easier to design systems of microelectrodes for dielectrophoretic separation, and tune their sub-micrometre features to achieve the maximum separation efficacy. The numerical model described in this text is also experimentally verified with the novel microelectrodes design for dielectrophoretic separation, which is successfully used to separate the mixture of different particles in the micron and sub-micron range.
37
Sergides, M. "Optical manipulation of micro- and nano-particles using evanescent fields." Thesis, University College London (University of London), 2013. http://discovery.ucl.ac.uk/1410938/.
Full textAbstract:
We present a study of the manipulation of micro-particles and the formation of optically bound structures of particles in evanescent wave traps. Two trapping geometries are considered: the first is a surface trap where the evanescent field above a glass prism is formed by the interference of a number of laser beams incident on the prism-water interface; the second uses the evanescent field surrounding a bi-conical tapered optical fibre that has been stretched to produce a waist of sub-micron diameter. In the surface trap we have observed the formation of optically bound one- and two-dimensional structures of particles and measured the binding spring constant by tracking particle motion and the extent of the particle’s Brownian fluctuations. Additionally, we have measured the inter-particle separations in the one-dimensional chain structures and characterised the geometry of the two-dimensional arrays. In the tapered optical fibre trap we demonstrated both particle transport for long distances along the fibre, and the formation of stable arrays of particles. We present the fabrication of tapered optical fibres using the 'heat-and-pull` technique, and evanescent wave optical binding of micro-particles to the taper. Calculations of the distribution of the evanescent field surrounding a tapered fibre are also presented. We show that the combination of modes can give control over the locations of the trapping sites. Additionally, we show how the plasmon resonance of metallic nano-particles can be exploited to enhance the optical trapping force, and suggest how a bi-chromatic nano-fibre trap for plasmonic particles may be implemented. In both experiments we implement video microscopy to track the particle locations and make quantitative measures of the particle dynamics. The experimental studies are complemented by light scattering calculations based on Mie theory to infer how the geometries of the particle structures are controlled by the underlying incident and scattered optical fields.
38
Keloth, Anusha. "Three dimensional optofluidic devices for manipulation of particles and cells." Thesis, Heriot-Watt University, 2017. http://hdl.handle.net/10399/3268.
Full textAbstract:
Optical forces offer a powerful tool for manipulating single cells noninvasively. Integration of optical functions within microfluidic devices provides a new freedom for manipulating and studying biological samples at the micro scale. In the pursuit to realise such microfluidic devices with integrated optical components, Ultrafast Laser Inscription (ULI) fabrication technology shows great potential. The uniqueness and versatility of the technique in rapid prototyping of 3D complex microfluidic and optical elements as well as the ability to perform one step integration of these elements provides exciting opportunities in fabricating novel devices for biophotonics applications. The work described in this thesis details the development of three dimensional optofluidic devices that can be used for biophotonics applications, in particular for performing cell manipulation and particle separation. Firstly, the potential of optical forces to manipulate cells and particles in ULI microfluidic channels is investigated. The ability to controllably displace particles within a ULI microchannel using a waveguide positioned orthogonal to it is explored in detail. We then prototype a more complex 3D device with multiple functionalities in which a 3D optofluidic device containing a complex microchannel network and waveguides was used for further investigations into optical manipulation and particle separation. The microfluidic channel network and the waveguides within the device possess the capability to manipulate the injected sample fluid through hydrodynamic focusing and optically manipulate the individual particles, respectively. This geometry provided a more efficient way of investigating optical manipulation within the device. Finally, work towards developing a fully optimised 3D cell separator device is presented. Initial functional validation was performed by investigating the capability of the device to route particles through different outlet channels using optical forces. A proof of concept study demonstrates the potential of the device to use for cell separation based on the size of the cells. It was shown that both passive and active cell separation is possible using this device.
39
Park, Seungkyung. "Electrokinetic and acoustic manipulations of colloidal and biological particles." [College Station, Tex. : Texas A&M University, 2008. http://hdl.handle.net/1969.1/ETD-TAMU-3199.
Full text
40
Flynn, Mary Frances. "Dielectrophoretic characterisation and manipulation of sub-micron particles following surface modification." Thesis, University of Glasgow, 2003. http://theses.gla.ac.uk/1946/.
Full textAbstract:
The aim of this thesis is to dielectrophoretically characterise sub-micron particles on the basis of their surface properties and to devise a DEP technique suitable for the fractionation and manipulation of particles on this scale. Polystyrene particles are modified by the attachment of biological ligands using various established localisation techniques and their DEP response observed using micro-electrodes with well defined high and low field regions, corresponding to a previously utilised design and modified in the course of this project for multiple sample handling. The results of these observations are modelled for the first time using a charge relaxation mechanism pertaining to a structured interfacial charge distribution and, through fitting the data to this model, fundamental parameters of the system - the surface conductance and electrokinetic charge - are predicted. The model viability is assessed with reference to both comparisons with alternative measurements and the technical limitations of the data fitting procedure, and corresponding surface charge transport mechanisms are discussed in the light of the DEP response following surface modification. Investigations are made into the possibility of a DEP based device suitable for the transport/fractionation of sub-micron particles. Given the essentially dissipative nature of sub-micro particle ensembles, a Brownian ratchet principle is chosen. A Brownian ratchet is a generic system wherein a net directional drive is effected by biasing Brownian diffusion on a periodically activated anisotropic structure. Without need of thermal gradients or net macroscopic forces Brownian ratchet pumps could be an interesting alternative in many microfluidic applications. Simulated fields and corresponding particle transport rates are compared for two basic electrode structures in order to assess their viability for use as DEP Brownian ratchets and a new design proposed, based on the simultaneous juxtaposition of positive and negative DEP forces. This device is built on the necessary scale using multi-layer fabrication techniques with a silicon elastomer moulded channel. The existence of stochastic transport on the device is investigated experimentally by means of processed video sequences and resulting possibilities for particle separation on the basis of size and surface properties inferred.
41
Lin, Yu-Sheng. "Tissue manipulation using nano-particles ferrofluids for minimal access surgical applications." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/8569/.
Full textAbstract:
Nano-scale Iron-Oxide ferrofluids exhibit a special property, ‘superparamagnetism’, that induces an attractive force toward an external magnetic field. The aim of this project is to investigate the use of ferrofluids for tissue retraction during Minimally Access Surgery (MAS). In the in-vivo porcine experiments, 0.3 ml of ferrofluid (200 mg/ml concentration) containing 10 nm particles is injected subserosally into the small bowel, respectively. A 0.6 T magnetic field is created using a combination of 10 mm and 20 mm diameter Neodymium Iron Boron magnets. The vertical retraction distance is measured up to 80 mm and video-recorded. The results demonstrate the capacity of ferrofluid to facilitate the tissue manipulation and analysis of the migration of the particles within the tissue using micro computed tomography (CT). A theoretical model developed to validate the experimental results is also beneficial for predicting retraction force. In conclusion, this feasibility study provides a protocol for systematically using small volumes of ferrofluid, without the need to mechanically grasp the tissue.
42
Leão, Neto José Pereira. "Força e torque de radiação sobre uma partícula viscoelástica em um fluido ideal." Universidade Federal de Alagoas, 2015. http://www.repositorio.ufal.br/handle/riufal/1695.
Full textAbstract:
The study of acoustic radiation force and torque phenomena has attracted an enormous interest of the scientific community, due to applications of these phenomena in noncontact particles manipulation. In this work, we perform a theoretical analysis of acoustic radiation force and torque exerted on a homogeneous visco elastic particle in the Rayleigh scattering limit (the particle radius is much smaller than the incident wavelength) by a wave with arbitrary geometry. Our study is based on the partial-wave expansion in spherical coordinates of the incident and scattered waves. In this context, the radiation force and torque are obtained analytically in terms of an infinite series which involves the scattering and incident expansion coefficients. We assume that the particle behaves as a linear viscoelastic solid, which obeys the fractional Kelvin-Voigt model. Analytical expressions for the radiation force and torque are obtained considering the low- and high-frequency approximation in the viscoelastic model. The developed theory is used to describe the interaction of acoustic waves (traveling and standing plane waves, and zero and first-order Bessel beams) with a low-and high-density polyethylene particle. Our results show that the axial acoustic radiation force might become negative (i.e. in opposition to the wave propagation direction) when a certain condition involving the physical parameters of the particle is satisfied. Negative acoustic radiation torque due a beam of first-order Bessel
may also occur when the same condition of negative radiation force is met. Remarkably, this is the first time that negative radiation force is predicted on a homogeneous particle in the Rayleigh scattering regime. Further more, the stability of the transverse acoustic radiation force generated by a Bessel beam is also investigated. We show a full 3D tractor Bessel vortex beam acting on the high-density polyethylene (HDPE). In the analysis of
acoustic radiation force generated on a viscoelastic particle by a standing plane wave, relevant deviations arose in comparison with the solid elastic model for the particles. The magnitude of the radiation force and torque on a HDPE described by the viscoelastic model behaves differently (negative radiation force) compared with other materials (solid elastic and compressible fluid particle) due to traveling plane wave and Bessel beams. Finally, we believe that this study may help further enhance the development of acoustic
levitation, particle handling in acoustofluids, and acoustical tweezers devices.<br>Coordenação de Aperfeiçoamento de Pessoal de Nível Superior<br>O estudo dos fenômenos de força e torque de radiação acústico tem atraído um enorme interesse da comunidade científica, devido a aplicações desses fenômenos em manipulação de partículas sem contato. Neste trabalho, realizamos uma análise teórica da força e torque de radiação acústico exercido sobre uma partícula visco elástica homogênea no limite do espalhamento de Rayleigh (o raio da partícula é muito menor que o comprimento de onda incidente) por uma onda com geometria arbitrária. Nosso estudo baseia-se na expansão de ondas parciais em coordenadas esféricas das ondas incidente e espalhada. Nesse contexto, a força e o torque de radiação são obtidos analiticamente em termos de uma série infinita que envolve os coeficientes de expansão das ondas espalhada e incidente. Assumimos que a partícula se comporta como um sólido viscoelástico linear, que obedece o modelo de Kelvin-Voigt fracionário. Fórmulas analíticas para a força e torque de radiação são obtidas considerando uma aproximação de baixa e de alta frequência no modelo viscoelástico. A teoria desenvolvida é usada para descrever a interação de ondas acústicas (onda plana progressiva, onda plana estacionária, feixes de Bessel de ordem zero e de primeira ordem) com partículas de polietileno de baixa e de alta densidade. Os nossos resultados mostram que a força de radiação acústica axial pode ser negativa (isto é, em oposição à direção de propagação da onda) quando uma determinada condição envolvendo os parâmetros físicos da partícula é satisfeita. Torque de radiação acústico negativo devido a um feixe de Bessel de primeira ordem também pode ocorrer quando a mesma condição da força de radiação negativa for atendida. Notavelmente, esta é a primeira vez que a força de radiação negativa é prevista sobre uma partícula homogênea no regime de espalhamento Rayleigh. Além disso, a estabilidade transversal da força de radiação acústica gerada pelo feixe de Bessel também é investigada. Mostramos que um feixe de Bessel trator 3D completo atua sobre uma partícula de polietileno de alta densidade (PEAD). Na análise da força de radiação acústica gerada sobre uma partícula viscoelástica por uma onda plana estacionária, desvios relevantes surgiram em comparação com partícula sólida elástica. A amplitude da força e torque de radiação sobre uma PEAD descrita pelo modelo viscoelástico apresenta um comportamento diferente (força de radiação negativa) comparados com os outros materiais (sólida elástica e fluida com absorção longitudinal) devido a onda plana progressiva e feixes de Bessel. Por fim, acreditamos que este estudo pode ajudar a melhorar ainda mais o desenvolvimento de dispositivos de levitação acústica, manipulação de partículas em acustofluídica e pinças acústicas.
43
Goodgame, Anne Louise. "Stark Rydberg states : probing and manipulating the ion core." Thesis, University of Oxford, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.249253.
Full text
44
Zouaghi, Ayyoub. "Manipulation de particules diélectriques micrométriques par ondes électrostatiques progressives et stationnaires - Études théorique, expérimentale et numérique." Thesis, Poitiers, 2019. http://www.theses.fr/2019POIT2296.
Full textAbstract:
Les convoyeurs électrostatiques à ondes progressives (COP) et stationnaires (COS) se présentent comme des moyens avantageux pour manipuler et transporter efficacement des particules sur une surface. L’objectif de cette thèse est d’étudier le comportement de particules diélectriques micrométriques sur ces systèmes. Les études expérimentales commencent par la caractérisation granulométrique et optique des particules et l’analyse de leur charge. Ensuite, l’efficacité de déplacement des particules par les deux types de convoyeurs est étudiée dans différentes conditions. Par ailleurs, les trajectoires des particules sont visualisées en utilisant une caméra ultra rapide. Un post-traitement des images obtenues en utilisant la vélocimétrie par suivi de particules (PTV) est mené pour calculer et étudier la vitesse des particules en fonction de différents paramètres. Les études théoriques et numériques menées avaient pour objectif d’étudier les ondes du potentiel électrique, la variation spatio-temporelle du champ électrique, et le bilan des forces mises en jeu. La dernière partie concerne la modélisation des trajectoires et le calcul numérique de la vitesse moyenne, ainsi que de la distance de déplacement des particules. Les résultats obtenus par modélisation sont en accord avec les observations et les calculs expérimentaux. Plusieurs modes de mouvement sont obtenus en fonction de la fréquence, la tension, la charge et la taille des particules. Les particules sont transportées plus efficacement dans le COP lorsqu’elles sont en mode synchrone sautillant. L’augmentation du nombre de phases permet à la fois de minimiser l’effet des ondes harmoniques inverses et d’augmenter la vitesse de propagation de l’onde directe ; cela mène à un déplacement plus rapide et plus loin des particules dans une seule direction, ce qui augmente l’efficacité du système<br>Traveling and standing wave electrostatic conveyors (TWC and SWC) are presented as advantageous techniques to effectively manipulate and transport particles on a surface. The aim of this work is to study the behavior of micrometer particles on these systems. Experimental studies begin with granulometric and optical characterization of particles and the measurement of their charge. Then, the particles displacement efficiency in both types of conveyors is studied under different conditions. In addition, the trajectories of the particles are visualized using high speed camera. The post-processing of the obtained images using Particle Tracking Velocimetry technique (PTV) is carried out to calculate and study the particles mean velocity and how it is affected by different parameters. The theoretical and numerical studies carried out aim to study the electric potential waves, the spatial and temporal variation of the electric field and the balance of the forces acting on particles. The last part concerns the modeling of particles trajectories and the numerical computation of their average velocity and displacement distance. The results obtained by modeling are in good agreement with the experimental observations and calculations. Several modes of movement are obtained depending on frequency, applied voltage value, as well as particle charge and size. Particles are transported more efficiently in the TWC when they are in synchronous hopping mode. Increasing the number of phases can minimize the effect of the backward harmonic waves and increase the speed of propagation of the forward wave that may help the particles to move faster and farther in one direction and lead to better displacement efficiency
45
Aardahl, Christopher L. "Electrodynamic trapping, manipulation, and Raman characterization of single particles and fine particulate clouds /." Thesis, Connect to this title online; UW restricted, 1997. http://hdl.handle.net/1773/9863.
Full text
46
Johansson, LarsErik. "Controlled manipulation of microparticles utilizing magnetic and dielectrophoretic forces." Licentiate thesis, Mälardalens högskola, Akademin för hållbar samhälls- och teknikutveckling, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-10544.
Full textAbstract:
This thesis presents some experimental work in the area of manipulation of microparticles. Manipulation of both magnetic and non magnetic beads as well as microorganisms are addressed. The work on magnetic bead manipulation is focused on controlled transport and release, on a micrometer level, of proteins bound to the bead surface. Experimental results for protein transport and release using a method based on magnetization/demagnetization of micron-sized magnetic elements patterned on a modified chip-surface are presented. Special attention has been placed on minimizing bead-surface interactions since sticking problems have shown to be of major importance when protein-coated beads are used. The work with non-magnetic microparticles is focused on the dielectrophoretic manipulation of microorganisms. Preliminary experimental results for trapping and spatial separation of bacteria, yeast and non-magnetic beads are presented. The overall goal was to investigate the use of dielectrophoresis for the separation of sub-populations of bacteria differing in, for example, protein content. This was, however, not possible to demonstrate using our methods.Within the non-magnetic microparticle work, a method for determining the conductivity of bacteria in bulk was also developed. The method is based on the continuous lowering of medium conductivity of a bacterialsuspension while monitoring the medium and suspension conductivities.
47
Dron, Olivier. "Micro-manipulation acoustique de particules : application aux mesures par micro-PIV." Paris 7, 2011. http://www.theses.fr/2011PA077242.
Full textAbstract:
"Aux micro-échelles, un éclairage en volume est obligatoire, contrairement à la nappe laser utilisée pour la vélocimétrie par image de particules (PIV). Pour recréer une nappe de particules éclairées, nous avons utilisé la force générée par une onde acoustique stationnaire piégée dans le canal et dirigée vers les noeuds de pression. Nous avons validé cette méthode avant d'en réaliser une étude paramétrique, qui fournit en particulier un phénomène de seuil pour l'influence de la concentration en particules. La valeur exacte de l'énergie acoustique dans le canal est nécessaire mais inconnue. Pour la déterminer, la trajectoire de la focalisation acoustique d'une particule, obtenue en utilisant les images de particules hors-champ, a été fittée par le modèle analytique, fournissant une valeur numérique pour l'énergie acoustique. Néanmoins, la position fixe du noeud de pression est une contrainte importante dans une perspective de vélocimétrie. Il s'est avéré qu"en modifiant la fréquence de l'onde acoustique émise, les particules de déplacent sur presque toute l'épaisseur du canal, de manière reproductible et sans hystérésis, permettant un contrôle simple et efficace des particules, ce qui est un résultat important mais contre-intuitif. Il a été montré que le seul paramètre intervenant dans ce phénomène résonant était la nature des plaques constitutives du canal, mais la nature exacte du phénomène demeure mal comprise. Enfin, l'apport de la focalisation acoustique a été quantifié sur des mesures de vélocimétrie, en comparant aux résultats sur des images brutes puis à ceux obtenus après un filtrage numérique. "<br>Unlike the laser sheet enlightnement used for Particle Image Velocimetry (PIV), a volume illumination is required to microscales. We used the acoustic force generated by an acoustic standing wave in the channel to focus the particles to the pressure nodes and thus create particles sheets. This method has been validated experimentally and a parametric study has been carried out, providing a threshold phenomenon for the influence of the particle concentration. To get the initially unknow acoustic energy value, the trajectory of a particle under acoustic focusing, obtained thanks to a defocused velocimetry method, has been fitted to the analytical law. However, the fixed focusing location is a strong limitation to the potential velocimetry measurements. It has been found that modifying the acoustic frequency changes the focusing location through all the channel height, in a reproductible way and without hysteresis, allowing an easy particle micromanipulation. It is not well-understood yet but it has been proven that the only physical parameter that has an influence on this resonance phenomenon is the nature of the constitutive plates of the channel. In the end, the improvement of the acoustic method has been quantified by comparing first to results obtained from the usual data and then to results obtained from filtered data
48
Rambach, Richard Walter [Verfasser], and Thomas [Akademischer Betreuer] Franke. "Akustische Manipulation mikroskopischer Tropfen und Partikel / Richard Walter Rambach ; Betreuer: Thomas Franke." Augsburg : Universität Augsburg, 2017. http://d-nb.info/1147682267/34.
Full text
49
Ogbi, Abdellah. "Modélisation de l'interaction champ électrique-particules diélectriques entre effets électromécaniques et aspects électrocinétiques : application aux cellules biologiques." Thesis, Lyon, 2016. http://www.theses.fr/2016LYSEC004/document.
Full textAbstract:
Dans ce travail, nous nous intéressons à l’interaction champ électrique-particule diélectrique dans les phénomènes diélectrophorétiques, aussi bien d’un point de vue théorique que numérique. L’application à long terme concerne l’électro- manipulation des cellules biologiques. La compréhension de ces phénomènes nécessite une modélisation complète des mécanismes de polarisation qui régissent l’interaction champ-particule, et met en oeuvre des modèles électromécanique et électroci- nétique. Après avoir introduit les différents phénomènes et notions nécessaires, nous abordons la modélisation de la polarisation à l’aide de la théorie du potentiel et proposons une approche pour déterminer numériquement les coefficients de polarisation identifiés. Nous montrons que, si le développement multipolaire peut se réduire au premier ordre pour le cas d’une particule sphérique plongée dans un champ uniforme, les ordres supérieurs sont nécessaires pour les particules non sphériques. Nous montrons également comment un processus d’homogénéisation permet d’étudier les configurations de particules multicouches avec cette approche. Dans le cadre de l’étude électromécanique des phénomènes diélectrophorétiques, nous mettons ensuite en œuvre cette approche multipolaire. Deux applications traitées numériquement sont présentées. Nous y montrons la pertinence de cette approche pour calculer la force et le couple exercés sur une particule dans des situations où le champ appliqué présente de fortes non-uniformités, l’approche dipolaire classique se révélant beaucoup moins performante dans ce cas. La particule et son milieu de suspension étant en réalité deux milieux en contact mais non-indépendants, des phénomènes électrocinétiques se produisent à l’interface. Ces effets interfaciaux sont abordés en vue de les prendre en compte dans le phénomène d’électrorotation d’une cellule biologique. Nous modélisons le problème complet d’une particule sphérique chargée plongée dans un milieu de suspension et soumise à un champ tournant en prenant en compte les effets électroosmotiques. La résolution par éléments finis de ce problème couplé montre la pertinence de l’approche développée, notamment pour les basses fréquences<br>In this work, we investigate about the interaction between electrical fields and dielectric particles in the dielectrophoretic phenomena, in theorical and numerical ways. The long-term application are related to electromanipulation and caracterisation of biological cells. Understanding these phenomena requires a complete modeling of polarization mechanisms governing the field-particle interaction and implements electromechanical and electrokinetic models. After introducing the necessary concepts and phenomena, we address polarization modeling using potential theory and suggest an approach for a numerical determination of polarization coefficients. We show that if the multipolar expansion can be reduced to the first order for the case of a spherical particle immersed in a uniform field, the higher orders are needed for nonspherical particles. We show also how a homogenization process allows the study of multilayered particles configurations using this approach. As part of the electromechanical study of dielectrophoretic phenomena, we implement the multipolar approach for two applications numerically treated. We show the relevance of this approach to calculate the force and torque exerted on a particle in situations where the applied field has strong non-uniformities, where the classical dipole approach turn out to be much less efficient. The particle and the suspending medium are in reality two media in contact but not independent as some electrokinetic phenomena occur at the interface. These interfacial effects are addressed in order to be taken into account in the electrorotation phenomenon of a biological cell. The model dealing with the whole problem of a charged spherical particle immersed in a suspension medium and subjected to a rotating field and taking into account the electroosmotic effects is treated. The resolution of the corresponding coupled problem using the finite element method shows the relevance of this approach
50
Morford, Casey Justin. "BitMaT - Bitstream Manipulation Tool for Xilinx FPGAs." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/36198.
Full textAbstract:
With the introduction of partially reconfigurable FPGAs, we are now able to perform dynamic changes to hardware running on an FPGA without halting the operation of the design. Module based partial reconfiguration allows the hardware designer to create multiple hardware modules that perform different tasks and swap them in and out of designated dynamic regions on an FPGA. However, the current mainstream partial reconfiguration flow provides a limited and inefficient approach that requires a strict set of guidelines to be met. This thesis introduces BitMaT, a tool that provides the low-level bitstream manipulation as a member tool of an alternative, automated, modular partial reconfiguration flow.<br>Master of Science