Dissertations / Theses on the topic 'Micromixer'
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1
Ferrante, Francesco. "Antisolvent Precipitation of L-Asparagine in a Commercial Micromixer." Thesis, KTH, Skolan för kemivetenskap (CHE), 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-146310.
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A commercial valve-assisted micromixer, manufactured by Ehrfeld (Germany), was tested for its use to precipitate L-asparagine from an aqueous solution using isopropanol as antisolvent. In a first part the mixing quality provided by the micromixer was studied by means of a competitive/parallel set of reactions following the approach of Baldyga, Bourne and Walker, Canadian J. Chem. Eng. 76 (1998) 641-649. Different experiments have been implemented and interpreted considering the average of Reynolds number of the inlet streams. Results show a good mixing quality that is comparable, in terms of absolute values of conversion, with other works present in literature. The precipitation experiments that followed revealed the limitation of the micromixer. The system was instable and particles adhesion occurred inside the mixing chamber. Improvements have been realized by changing the spring tension of the valve and introducing a commercial surfactant TRITON X-100.
2
Wang, Hengzi, and na. "Passive mixing in microchannels with geometric variations." Swinburne University of Technology, 2004. http://adt.lib.swin.edu.au./public/adt-VSWT20061013.162737.
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This research project was part of the microfluidic program in the CRC for Microtechnology,
Australia, during 2000 to 2003. The aim of this research was to investigate the feasibility of
applying geometric variations in a microchannel to create effects other than pure molecular
diffusion to enhance microfluidic mixing. Geometric variations included the shape of a
microchannel, as well as the various obstacle structures inside the microchannel.
Generally, before performing chemical or biological analysis, samples and reagents
need to be mixed together thoroughly. This is particularly important in miniaturized Total
Analysis Systems (�TAS), where mixing is critical for the detection stage. In scaling
down dimensions of micro-devices, diffusion becomes an efficient method for achieving
homogenous solutions when the characteristic length of the channels becomes sufficiently
small. In the case of pressure driven flow, it is necessary to use wider microchannels to
ensure fluids can be pumped through the channels and the volume of fluid can provide
sufficient signal intensity for detection. However, a relatively wide microchannel makes
mixing by virtue of pure molecular diffusion a very slow process in a confined volume of
a microfluidic device. Therefore, mixing is a challenge and improved methods need to be
found for microfluidic applications.
In this research, passive mixing using geometric variations in microchannels was studied
due to its advantages over active mixing in terms of simplicity and ease of fabrication.
Because of the nature of laminar flow in a microchannel, the geometric variations were designed
to improve lateral convection to increase cross-stream diffusion. Previous research
using this approach was limited, and a detailed research program using computational fluid
dynamic (CFD) solvers, various shapes, sizes and layouts of geometric structures was undertaken
for the first time. Experimental measurements, published experimental data and analytical predictions were used to validate the simulations for selected samples. Mixing
efficiency was evaluated by using mass fraction distributions. It was found that the overall
performance of a micromixer should include the pressure drop in a microdevice, therefore,
a mixing index criterion was formulated in this research to combine the effect of mixing
efficiency and pressure drop. The mixing index was used to determine optimum parameters
for enhanced mixing, as well as establish design guidelines for such devices.
Three types of geometric variations were researched. First, partitioning in channels
was used to divide fluids into mixing zones with different concentrations. Various designs
were investigated, and while these provided many potential solutions to achieving good
mixing, they were difficult to fabricate. Secondly, structures were used to create lateral
convection, or secondary flows. Most of the work in this category used obstacles to disrupt
the flow. It was found that symmetric layouts of obstacles in a channel had little effect
on mixing, whereas, asymmetric arrangements created lateral convection to enhance crossstream
diffusion and increase mixing. Finally, structures that could create complex 3D
advections were investigated. At high Reynolds numbers (Re = 50), 3D ramping or obstacles
generated strong lateral convection. Microchannels with 3D slanted grooves were
also investigated. Mixers with grooved surfaces generated helicity at low Reynolds numbers
(Re � 5) and provided a promising way to reduce the diffusion path in microchannels
by stretching and folding of fluid streams. Deeper grooves resulted in better mixing efficiency.
The 3D helical advection created by the patterned grooves in a microchannel was
studied by using particle tracing algorithms developed in this research to generate streaklines
and Poincare maps, which were used to evaluate the mixing performance. The results
illustrated that all the types of mixers could provide solutions to microfluidic mixing when
dimensional parameters were optimized.
3
Farangis, Zadeh Hamid. "Experimental validation of flow and mass transport in an electrically excited micromixer." Karlsruhe : FZKA, 2005. http://bibliothek.fzk.de/zb/berichte/FZKA7152.pdf.
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Bessoth, Fiona Gabriele. "Microstructure for efficient continuous flow mixing." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.367869.
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HONG, CHIEN-CHONG. "ON-CHIP PASSIVE FLUIDIC MICROMIXER AND PRESSURE GENERATOR FOR DISPOSABLE LAB-ON-A-CHIPS." University of Cincinnati / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1100898243.
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Hong, Chien-Chong. "On-chip passive fluidic micromixer and pressure generator for disposable Lab-on-a Chips." Cincinnati, Ohio : University of Cincinnati, 2004. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=ucin1100898243.
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Asano, Shusaku. "Rational Design of Micromixers and Reaction Control in Microreactors." Kyoto University, 2018. http://hdl.handle.net/2433/232008.
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8
Lilly, David Ryan. "VIABILITY OF A CONTROLLABLE CHAOTIC MICROMIXER THROUGH THE USE OF TITANIUM-NICKEL SHAPE MEMORY ALLOY." UKnowledge, 2011. http://uknowledge.uky.edu/me_etds/1.
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Microfluidic devices have found applications in a number of areas, such as medical analysis, chemical synthesis, biological study, and drug delivery. Because of the small channel dimensions used in these systems, most microchannels exhibit laminar flow due to their low Reynold’s number, making mixing of fluids very challenging. Mixing at this size scale is diffusion-limited, so inducing chaotic flow patterns can increase the interface surface area between two fluids, thereby decreasing overall mixing time.
One method to create a chaotic flow within the channel is through the introduction of internal protrusions into the channel. In such an application protrusions that create a rotational flow within the channel are preferred due to their effectiveness in folding the two fluids over one another. The novel mixer outlined in this paper uses a Ti-Ni shape memory alloy for the creation of protrusions that can be turned controlled through material temperature. Controllability of the alloy allows users to turn the chaotic flow created by the protrusions off and on by varying the temperature of the mixer. This ability contributes to the idea of a continuous microfluidic system that can be turned on only when necessary as well as recycle unmixed fluids while turned off.
9
Reynol, Alvaro. "Modelagem e simulação de micromisturadores." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3137/tde-24092008-141009/.
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A microfluídica juntamente com a intensificação de processos são duas áreas de pesquisa interessadas no estudo e desenvolvimento de processos em escala micrométrica capazes de manipular diminutas quantidades de reagentes. Para tanto, estes devem contar com dispositivos de pequena escala de tamanho e ao mesmo tempo serem tão confiáveis e eficientes quanto os de escala industrial. Uma das operações unitárias envolvidas nesses processos é a agitação. Em função da ordem de grandeza dos equipamentos e dos materiais em que são fabricados, grandes diferenciais de pressão não podem ser aplicados nos mesmos e como conseqüência no interior dos micromisturadores, como são conhecidos tais equipamentos, o escoamento se dá em regime laminar, sob está condição o processo de mistura é controlado pela difusão entre os componentes. Uma maneira de superar esta dificuldade é gerar no interior do micromisturador o aparecimento de um escoamento caótico. Para tal, podem-se utilizar fontes de energia externa (micromisturadores ativos) ou a própria energia do escoamento (micromisturadores passivos) através da construção de geometrias especiais. O desenvolvimento em laboratório destes equipamentos demanda tempo e geralmente é oneroso. A principal alternativa para este trabalho é a dinâmica dos fluidos computacional (CFD), ferramenta aplicada no presente estudo para analisar três geometrias diferentes propostas e analisadas experimentalmente no trabalho de Cunha (2007). Para caracterizar o funcionamento dos mesmos foram testadas quatro vazões distintas, com as quais foi possível levantar os perfis de pressão, velocidade e fração mássica de dois componentes que eram misturados. Com o intuito de demonstrar a eficiência dos equipamentos dois parâmetros foram analisados: o avanço da qualidade da mistura e a perda de carga para as diferentes condições operacionais. Apesar da limitação da malha e de não ter-se obtido resultados independentes da malha, foi possível se fazer uma comparação entre as três geometrias e identificouse que os micromisturadores M2 e M3 são os que apresentam o melhor desempenho para a faixa de vazão simulada (120 < Re < 1200).Microfluidics and process intensification are two research areas interested in the study and development of new micrometric-scale devices capable of manipulating and processing small quantities of reagents. These processes have to deal with small scale equipment and at the same time be as reliable and efficient as the large-scale one. Because of the scale of this equipment and the material it is made of, large pressure differential is not possible, as a consequence in the interior of the micromixers, as they are known; a laminar flow develops, under those circumstances the mixing process is controlled by the diffusion mechanism between the two components. One way to suppress this deficiency is to generate a chaotic flow on the micromixer, which can be done by using external energy (active micromixer) or its own flow energy (passive micromixer) through special geometry construction. The experimental development of such microdevices demands time and, generally, is very expensive. The main alternative for this activity is the use of computational fluid dynamics; this tool was employed on this work with the aim of studying three geometries proposed by Cunha (2007). To characterize their working process, four different volumetric flows were simulated and analyzed the pressure, velocity and mass fraction profiles. Two parameters were calculated in order to characterize their efficiency: the mixture quality along the micromixers cross sections and the pressure drop for different operational conditions. Although we have mesh size limitations and a mesh independent results were not obtained it was possible to compare the three micromixers geometries and it was found out that both M2 and M3 micromixers had the best performance under operational conditions tested (120 < Re < 1200).
10
Loy, Dominik [Verfasser], and Ernst [Akademischer Betreuer] Wagner. "Development of an automated micromixer for the controlled formulation of multi-component polyplexes / Dominik Loy ; Betreuer: Ernst Wagner." München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2021. http://d-nb.info/1232176273/34.
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McKay, Terri L. "A CFD Model of Mixing in a Microfluidic Device for Space Medicine Technology." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1305563573.
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Farangis, Zadeh Hamid [Verfasser]. "Experimental validation of flow and mass transport in an electrically excited micromixer / Forschungszentrum Karlsruhe GmbH, Karlsruhe. Hamid Farangis Zadeh." Karlsruhe : FZKA, 2005. http://d-nb.info/976567865/34.
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Debas, Hélène. "Émulsification en systèmes microstructurés." Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL075N/document.
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Cette thèse, intitulée « Emulsification en systèmes microstructurés », s’inscrit au sein de la tâche « Emulsification contrôlée » du projet européen IMPULSE. Deux micromélangeurs en acier inoxydable, un V-type et un Caterpillar, ont été testés en utilisant un pilote d’émulsification continue. Ces dispositifs conçus en acier inoxydable et fonctionnant comme des boîtes noires, des micromélangeurs transparents ont ensuite été utilisés afin de comprendre leurs mécanismes d’émulsification. Les paramètres-clés intervenant dans la formation de gouttes à un orifice à l’échelle macroscopique ont dans un premier temps été identifiés. A l’échelle microscopique, la formation des gouttelettes dans le micromélangeur V-type est issue de la mise en contact des jets des phases aqueuse et organique formés à la sortie de ce dispositif et d’un phénomène élongationnel avec des instabilités interfaciales. Dans le cas du Caterpillar, la taille des gouttelettes dépend de la géométrie interne des éléments en série de ce micromélangeur. La formation des gouttelettes est issue d’un phénomène de cisaillement au niveau de la jonction en Y. La réduction de la taille de ces gouttelettes est ensuite due à leur passage dans les éléments de mélange. L’utilisation de micromélangeurs transparents a, quant à elle, permis de caractériser davantage ces deux micromélangeurs par micro-PIV et caméra rapide. Enfin, une dépendance du diamètre des gouttelettes par rapport à l’énergie dissipée est constatée pour le Caterpillar mais par pour le V-type. L’énergie dissipée dans ces deux micromélangeurs semble être moindre et les émulsions formées de meilleure qualité par rapport aux procédés classiques d’émulsificationThis thesis, entitled “Emulsification in micromixers” was carried out within the framework of the Task “Controlled Emulsification” of the European IMPULSE project. Two micromixers in stainless steel, the V-type and the Caterpillar, were tested in an experimental setup. These microdevices working as black boxes, transparent micromixers were used after to gain insight into the fundamental mechanisms for emulsification. Firstly, the key parameters enabling the drop formation at macroscopic scale were identified. At microscopic scale, the droplet formation in the V-type micromixer results from the contact of aqueous and organic phases jets at the outlet of the microdevice and from elongational phenomena with interfacial instabilities. In the case of the Caterpillar, the droplets size depends on the internal geometry of the microdevice. The droplet formation can be mainly attributed to the shearing phenomena at the Y-junction. The decrease of the droplets’ size is then due to their passage through the mixing elements in series in the outlet channel. Moreover, the use of transparent micromixers allows to characterize these two micromixers by the micro-PIV and high speed camera. A straightforward relationship between the energy dissipation and the size of droplets was established for the Caterpillar, but not for the V-type. Moreover, the energy dissipation within these two micromixers is lower and the emulsions obtained having a more satisfactory quality than in the case of the classical emulsification processes
14
Azizi, Farouk. "Microfluidic Chemical Signal Generation." Cleveland, Ohio : Case Western Reserve University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=case1244664596.
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Thesis(Ph.D.)--Case Western Reserve University, 2009Title from PDF (viewed on 2009-11-23) Department of Electrical Engineering Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center
15
Li, Lei. "Investigation of the Optical Effects of Single Point Diamond Machined Surfaces and the Applications of Micro Machining." The Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=osu1252435737.
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LEE, SE HWAN. "Polymer Lab-on-a-Chip with Functional Nano/Micro Bead-Packed Column for Biochemical Analysis." University of Cincinnati / OhioLINK, 2008. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1212166774.
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Yu, Wei. "Development of an elongational-flow microprocess for the production of size-controlled nanoemulsions : application to the preparation of composite and hybrid polymeric microparticles." Thesis, Strasbourg, 2015. http://www.theses.fr/2015STRAE027/document.
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L’objectif de ce travail fut de développer et d’étudier les performances d’un microprocédé basse pression à écoulement élongationnel pour la production de nanoémulsions polymérisables de tailles contrôlées et de distributions de taille étroites. Le diamètre des nanogouttelettes a pu être précisément ajusté dans la gamme 50-300 nm en modifiant simplement les paramètres de procédé : le débit réciproque au travers du micromélangeur, le nombre de cycles et la dimension caractéristique du microcanal. Les nanoémulsions produites furent, dans une seconde étape, polymérisées par voie thermique ou par irradiation UV afin de générer des suspensions colloïdales de nanoparticules de polymère de tailles également contrôlées (87-360 nm). Un monomère, un agent de réticulation ainsi qu’un amorceur thermique ou photochimique appropriés furent par la suite ajoutés au milieu continu de ces nanosuspensions. Les solutions résultantes servirent comme phases dispersées dans des générateurs microfluidiques de gouttelettes à capillaires. Les microgouttelettes de taille contrôlée ainsi produites furent polymérisées en ligne par irradiation UV pour donner lieu à des microsphères ou à des microparticules coeur-écorce composites de polymère toutes deux dopées avec des nanoparticules de polymère. Des microparticles composites et hydrides comportant des nanoparticules d’or dans le coeur et d’argent dans l’écorce furent également obtenues grâce à la réduction photochimique in situ des sels précurseurs lors de la photopolymérisation des microgouttelettes. Ce travail a démontré l’efficacité d’un nouveau dispositif microfluidique basse énergie pour la production de nanoémulsions et leur emploi pour la synthèse de matériaux polymères morphologiquement complexesThe aim of this work was to develop and to study the performances of a low pressure elongational-flow microprocess for the production of size-controlled polymerizable nanoemulsions with narrow size distributions. Nanodroplets diameter was easily tuned in the size range 50-300 nm by varying the process parameters, namely the reciprocating flow rate through the micromixer, the number of cycles and the characteristic dimension of the microchannel. Obtained nanoemulsions were in a second step thermally or UV-assisted polymerized to give colloidal suspensions of size-tunable polymer nanoparticles (87-360 nm). Then, a proper monomer, crosslinker and thermal- or photo-initiator were added to the continuous phase of these nanosupensions. The resulting mixtures were used as the dispersed phases of two different capillaries-based microfluidic droplet generators. The produced sizecontrolled microdroplets were finally UV polymerized online and plain as well as core-shell composite polymeric microparticles doped with lower scale polymer nanoparticles were obtained. Composite/hybrid polymeric core-shell microparticles were also synthesized for which gold nanoparticles in the core and silver nanoparticles in the shell were synthesized in situ from their salt precursors during microdroplets polymerization. This work has demonstrated the high efficiency of a novel low energy microfluidic emulsification device for the production of nanoemulsions which were used for the synthesis of morphologically complex polymeric materials
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Abrahám, Martin. "Návrh mikrofluidického směšovače." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2016. http://www.nusl.cz/ntk/nusl-241127.
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Microfluidic devices are more frequently being used in medicine as they operate with small amounts of test samples, such as blood or reagent chemicals. To work with such substances, effective mixing of the solution is usually required, which emerged as the most challenging problem in microfluidic systems. Due to the minor dimensions of the devices only laminar flow occurs, thus the turbulent eddies do not contribute to the mixing, but only the molecular diffusivity.
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Huang, Chi-Ming, and 黃啟明. "A Study of Micromixer." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/09124962801729938742.
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碩士國立臺灣大學
應用力學研究所
89
In the recent decades, the mixing of two or more fluids in small scale within a reasonable amount of time has raised a wide interest in the fields of TAS (Total Analysis System), drug delivery, biomedical diagnose, and fast drug discovery. However, the traditional ways for mixing enhancement, such as turbulence, three-dimensional flows, and mechanical actuation, can neither function well nor work efficiently in micro scale. This proposal introduces Two innovative ways to elegantly employ liquid surface tension and micro structure to dramatically increase liquid contact surface and reduce diffusion length, which leads to a mixing time scale from microseconds to milliseconds. First, the surface tension between the fluids and the base will be modified by use of the voltage difference, thus, a driving force will be created to move the fluids. And the third, based on the same principle, the surface tension at certain specific locations can be manipulated by heating. This device can also be batch-fabricated and fully integrated with IC or other micro fluid devices to serve as a low-cost "on-chip" MEMS fluid system.
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Huang, Min-Zhong, and 黃閔忠. "Design and fabrication of micromixer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/89436560320011998921.
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碩士國立屏東科技大學
材料工程研究所
93
This study presents a novel technique in which low-frequency periodic electrokinetic driving forces are utilized to mix electrolytic fluid samples rapidly and efficiently in a double-cross-form microfluidic mixer. Without using any additional equipment to induce flow perturbations, only a single high voltage power source is requires for simultaneously driving and mixing the sample fluids which results in a simple and low-cost system for the mixing purpose. The effectiveness of the mixer as a function of the applied electric field and the periodic switching frequency is characterized by the intensity distribution calculated downstream from the mixing zone. The present numerical and experimental results confirm that the proposed double-cross-form micromixer has excellent mixing capabilities. The experimental and numerical results show that a mixing performance of 98% can be achieved within a mixing channel of length 1.6 mm when a 150 V/cm driving voltage and a 5 Hz switching frequency are applied. The relationship between the mixing performance, switching frequency, and main applied electric field is derived. It is found that the optimal switching frequency depends upon the magnitude of the main applied electric field. This current study also proposes a T-shape mixer with 45° parallelogram barriers (PB) for fast mixing two sample fluids utilizing naturally electrokinetic instability induced shedding effects while a DC electric field is applied. In stead of using delicate equipment and moving parts in microchip devices to induce flow perturbations, a single high-voltage power source is utilized for simultaneously driving and mixing the sample fluids. A simple and low-cost system for mixing purpose can be achieved with this approach. The effectiveness of the mixer as a function of the applied electric field and the width of 45° parallelogram barriers is characterized by measuring the fluorescence concentration distribution downstream from the mixing zone. The experimental results indicate that the mixing performance can be as high as 91% within a mixing length of 2.5 mm downstream from the T-junction with parallelogram barriers of four-fifth the channel width at the applied electric field of 400V/cm. The novel micromixing method presented in this study provides a simple solution to mixing problems in the Lab-on-a-Chip systems.
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Aliyari, Nasrin. "Performance Evaluation Of H-shaped Micromixer." Master's thesis, 2017. http://hdl.handle.net/10316/95972.
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Documentos apresentados no âmbito do reconhecimento de graus e diplomas estrangeirosCompared to conventional macroscopic methods, microfluidic devices have the advantages of reduced solvent, reagent and cell consumption, shorter reaction times, portability, low cost and low power consumption. This study propose two novel generation of three Dimensional splitting and recombination passive micromixers (the longitudinal and cross-sectional unbalanced micromixer) that are designed based on the H-shaped balanced micromixer geometry. Numerical simulation were performed to study the mixing dynamics of two miscible liquids(water & ethanol) in all three types of micromixers and results compared with the previous well-known H-shaped balanced micromixer. Laminar flow regime, incompressible, steady and no-slip velocity are Assumptions that govern fluid flow. It was found that mixing index and pressure drop are significantly affected by the unbalancing and depends on Reynolds number (inlet velocities). increasing the Reynolds number will increase mixing index, at Re=100 the mixing index of the cross-sectional unbalanced micromixer is more than 90% while at Re=20 this is less than 70%. Creating an unbalanced flow will increase mixing index, however, cross-sectional unbalancing is more effective than longitudinal unbalancing, at Re=100 the mixing index of the cross-sectional unbalanced micromixer has increased about 30% compared to the H-shaped balanced micromixer. Numerical results show that increasing the Reynolds number will increase pressure drop of all three types of micromixers. Compared with each other, the longitudinal unbalanced micro mixer and the H-shaped balanced micromixer with equal pressure drop, have 25% lower pressure drop than the cross-sectional unbalanced micromixer.
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Chang, Chih-Hsiang, and 張智翔. "Development of a Novel Semi-Active Micromixer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/14084787408021279446.
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碩士國立臺灣大學
機械工程學研究所
95
The purpose of this essay is to propose a novel micro-mixer. The structure of the proposed mixer is as simple as that of the traditional passive mixer. Furthermore, the working flow of this assay is a kind of controllable nano-magnetic fluids therefore it can be twisted or squeezed like a magnetic rod once an external magnetic field is applied. To combine the advantages mentioned above, instead of an active mixer, an external magnet is employed in our research. With the simple dragonfly type of micro-fluidic channel, the fluid can be formed as the droplet shape by this passive structure. The oil-based agent magnetic working fluid is magnetized to squeeze the droplets and enhance the mixing efficiency. This type of mixer is called a “Semi-Active Micromixer”. First we focus on the refinement of the agent of nano-magnetic fluids. The results show that different experimental environments have effects on the characteristics of the fluid by using Taguchi method. Three controlled parameters, the way of pouring, the way of heating, and the modification of the Ammonium Oil acid are tested for the experiments. The optimal conditions are as follows. (1). Use Fe ionized solution to titrate the sodium hydroxide solution. (2). Stir the mixing fluid at 90 oC. (3). Adopt 5 mg: 5 mg as the proportion of oleic acid and ammonia. The magnetization is 0.96emu/g for optimal water-based magnetic fluids of 0.05M. The magnetization is 7.98emu/g, 6.56emu/g and 4.73emu/g for oil-based magnetic fluids of 0.5M, 0.25M, 0.125M respectively at the external magnetic filed of 13500 Oe. All the ferrofluids illustrates the characteristic of superparamagnety. The MEMS process and soft lithography technique were employed to fabricate the micro-mixer device.The final results of the experiments focus on the mixing efficiency of the novel mixer. The oil-based magnetic fluid, transparent DI water and the blue dye are injected through the inlets respectively. The resultes show that: (1).The mixing uniformaity is more stable as closer to the end the microchannel when the same concentration of the magnetic fluid is applied. (2).The mixing is more uniform when stronger magnetic field is applied. (3).The mixed fluid is more uniform when the concerntration of the magnetic fluid is higher.
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Huang, Kuo-Hsiu, and 黃國修. "Development of a Novel Herringbone-type Micromixer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/98366372486646489226.
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碩士國立臺灣大學
機械工程學研究所
94
It is well-known that in microscale fluidic mixing is extremely difficult, and requires long mixing time as well as long mixing length. In this research, we present a novel herringbone patterns for micro-mixers. The concept of the design is to periodically change the lengths of the herringbone structures built on the bottom surface of a micro channel. These herringbone structures effectively generate chaotic advection and diffusion effects to stir the flow and induce fluidic mixing. The micromixers are fabricated using MEMS process. The molds of the herringbone and channel patterns are fabricated on silicone wafers using an ICP-RIE etcher. The replicas are made by curing PDMS on the molds. The mixing behaviors of the fabricated micromixers have been observed by using both an optical microscope and a fluorescence microscope. It is demonstrated that with the periodically changed lengths of the herringbone patterns, through continuously stretching and squeezing the fluids, chaotic advection is generated. It also disturbs the flow field to speed up the diffusion effect between the flows. At the condition of extremely low Reynolds number (Re=0.189), a channel length of about 10mm is required for complete mixing.
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Chen, An-Pang, and 陳安邦. "Numerical Investigation of a Passive Micromixer Design." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/94472881525019526411.
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碩士國立成功大學
航空太空工程學系碩博士班
96
This study adopts Computation Fluid Dynamics (CFD) as the research tool to study the mixing efficiency of various designs of 3-dimensional T-tube micromixers. The mixer design is based on the principle of molecular diffusion at low Reynolds number flow regime. Taking the length of the tube required for 99% mixing efficiency (L99%), as the principal design parameter, this study discusses the relationship among L99%, the diffusivity, the volume flow rate through the mixer, the cross sectional area of the tube, the hydraulic diameter of the tube, the pressure difference required to drive the flow, and the top view area of the mixer. It is found that keeping a constant cross sectional area is an effective way to prevent the increase of pressure difference across the mixer. It is also found that by reducing the diffusion distance of the mixer, the required L99% can be effectively reduced.
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Liu, Jun-Ting, and 劉俊廷. "Stereolithographic 3D Printing of Archimedes Screw Micromixer." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/67490114669672546221.
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碩士國立臺灣大學
機械工程學研究所
105
Micromixers can be classified as passive or active micromixers. Passive micromixers improve mixing efficiency mainly by changing the geometry. When changing the geometry, it’s also necessary to keep the flow of microchannel without obstruction at the same time. So Archimede’s Screw is printed in the microchannel in this thesis. Taking advantage of thin-wall and multi-directional property of Archimede’s Screw, increasing mixing efficiency and keeping the channel permeable could simultaneously be expected. Although microstructure fabrication could be achieved successfully by using MEMS technology, it’s still difficult to produce multi-directional curved surface structure by using MEMS technology due to the limitation of mask. 3D Printing technology can manufacture complex surface with layer-by-layer technique but still has some difficulties in producing micron-level structure. This thesis investigates how to use DLP technology to fabricate micro and curved surface structure. At first refitting the sleeve of commercial projector has been executed. Then the effect of the exposure time, the layer thickness and the composition of resin on the process have also been studied. The objective is to produce the microstructure almost as same as adopting TPP(Two-photon Polymerization) by using DLP technology. Finally, micron-level Archimede’s Screw is successfully printed in the microchannel and mixing test has been done. The results reveal that this improved DLP technology has the ability to print the channel with a minimum width of 750 .
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Chien-Fu, Chen, and 陳建甫. "A Study of Surface Tension Driven Micromixer." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/34869925352625235375.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
90
Abstract In the recent decades, the mixing of two or more fluids in small scale within a limited amount of time has raised a wide interest in the fields of TAS (Total Analysis System), drug delivery, biomedical diagnose, and fast drug discovery. However, the traditional ways for mixing enhancement, such as turbulence, three-dimensional flows, and mechanical actuation, can neither function well nor work efficiently in micro scale. This thesis introduces innovative ways to elegantly employ liquid surface tension and micro structure to dramatically increase liquid contact surface and reduce diffusion length, which leads to a mixing time scale from microseconds to milliseconds. This device can also be batch-fabricated and fully integrated with IC or other micro fluid devices to serve as a low-cost "lab on a chip" MEMS fluid system.
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Liao, Chun-Yi, and 廖峻儀. "Design, Simulation and Optimization of a Micromixer." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/34346755791301594421.
Full textAbstract:
碩士國立臺灣大學
機械工程學研究所
100
Design, simulation and optimization of a serial lamination micromixer are adapted with the concept of vortex-producing obstacle. Although the fluid motion is three-dimensional, the channel merely requires a simple fabrication process of adhering two layers of polymer. Optimization is analyzed with two main geometric parameters of the design. Simulation through one computational fluid dynamics software is used to optimize these two variables, while taking into consideration the physical properties of the fluid, i.e., viscosity and the Reynolds number. By additional consideration of the velocity field, a new mixing index is created based on the traditional mixing index. The inherent advantage of this new mixing index is that it always produces smoother curves than that of the traditional one. Optimization results are achieved by using the regression analysis with the two geometric parameters
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Hsu, Hui-Ting, and 許惠婷. "The Design and Research of Passive Micromixer Arrays." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/25110077519021854587.
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Jia-JiaChen and 諶佳佳. "The numerical simulation of a passive micromixer design." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/61810842385129083065.
Full textAbstract:
碩士國立成功大學
航空太空工程學系碩博士班
98
The low Reynolds number flow field of a novel micromixer design is studied in detail using Computational fluid dynamics. The mixer being studied is based on the T-tube micromixer with a converter section added to the beginning of the main flow channel. The converter is designed to increase the number of mixing interface and to decrease the mixing distance necessary for a complete mixing. In this work a converter capable of generating three interface and cutting the mixing distance by half is designed and studied in defuel.
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Kung, Chun-fei, and 宮春斐. "A Novel Design for an Effective Passive Micromixer." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/47737913894898253037.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
91
Abstract In the micro scale, it is a very important subject to let two or more fluids mixing completely in a short time. In the recent decades, it has raised a wide interest in many application of bio-detection, like drug delivery, biomedical diagnose, DNA analysis, and fast drug discovery. However, the traditional ways for mixing enhancement, such as turbulence, three-dimensional flows, and the external force can neither function well nor work efficiently in micro scale. This paper proposes a new type of high efficient micro mixer, which without any active devices such as pumps, valves, or external energies. These energies are electrostatic, or magnetic fields. In this novel mixing device, the surface tension force from the working fluid is the only energy resource employed passively to transport liquid. Then the herringbonelike structure is arranged on the bottom of the channel, which can let liquid to produce three-dimensional fluid field automatically. It also can greatly improve the mixing efficiency to achieve the goal of rapidly and mixing completely. This device can also be batch-fabricated and applied to power-free mTAS or low-cost lab on a chip MEMS fluid system.
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蔡昆志. "Hydrodynamic analysis of fluidic oscillators and micromixer design." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/27141787276726757800.
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Liao, Chong-Yao, and 廖崇耀. "A Passive Micromixer Design Based on Molecular Diffusion." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/60464083370598896353.
Full textAbstract:
碩士國立成功大學
航空太空工程學系碩博士班
95
This study adopts Computation Fluid Dynamics (CFD) as the research tool to study the mixing efficiency of a T-tube micromixer desigh based on the principle of molecular diffusion at low Reynolds number flow regime. The effect of reducing channel width or depth on the mixing efficiency is studied. It is found that a reduced channel width can effectively reduce the required time and channel length for total mixing. The long and straight main channel of the mixer can be tightly wound into a roughly squared region to prevent the excessive increase of mixer dimension. In 3D simulation, as the channel width is being reduced, the channel depth can be enlarged to keep a constant cross section area, such that the pressure difference required to drive the channel flow will not undergo dramatic increase. Finally, to prevent the possible excessive increase of channel depth, a flow-direction converter can be applied to rotate the orientation of the contact surface between the two mixing fluids from vertical to horizontal.
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Chia-YuamTsao and 操佳遠. "A study on synthesis of silica nanoparticle using micromixer." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/00673301670855390602.
Full textAbstract:
碩士國立成功大學
機械工程學系專班
98
In this thesis, silica nanoparticles were synthesized by the sol - gel method and collocated with high efficiency PDMS micromixer. High efficiency micromixing provides small particles so that the uniformity of size distribution is enhanced, Particle size was analyzed by scanning electron microscopy (SEM). The study sol-gel process parameters and the changes made the following studies in relationship. between nanoparticles to factors of TEOS concentration, reaction temperature, tube diameter size, reaction time, different concentrations of ammonia and water were discussed. The experiment results showed that larger silica nanoparticles were formed with increasing the concentration of TEOS and ammonia. In addition, reduced reaction tube diameter can quickly produce larger silica nanoparticles. Compared with the sol-gel method in glass, the increase of reaction temperature and amount of deionized water reduced the particle size. The size of silica nanopartilces synthesized by our method is around 38-93 nm.
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Liu, Hsin-Ping, and 劉新平. "A Rapid Micromixer via 3D Counter-Rotating Circulatory Flow." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/36473704783978244130.
Full textAbstract:
碩士國立臺灣大學
應用力學研究所
96
This work presents an ultra-fast micromixer via a pair of 3D, counter-rotating, circulatory flow structure. This feature is secondary steady streaming induced by a resonating gold-coated suspended structure, consisting of two long beams (400um length) supporting a microplate (100um × 200um) at the center. As AC current passes through this structure, an external magnet placed underneath forcing the microplate to in-plane resonance as result of Lorentz law. Two heterogeneous streams passes the 3D circulatory flow results in a mixing efficiency increase of 72% within 900μm mixing length, under background flow speed of 36.4mm/s, Pèclet number of 6.61×104, Reynold’s number of 1.72. For background flow speed of 10mm/s and 5mm/s, 71% and 56% of increase mixing efficiency under same mixing length of 900μm, implies a mixing efficiency independent of Reynold’s number. Application of the device to enhance lysis of erythrocytes is made by in-flowing of the cells in one stream and lysis solution in another. Results showed a 68% lysis rate could be obtained within 1cm mixing length, where as only 0.7% for a straight channel. Furthermore, lysis rate could be controlled by excited AC voltage on the oscillating plate according to results obtained, which could provide an environment for erythrocyte lysis and prevent stress target cells for extended period in macroscale isolation, which could avoid differentiations caused by manual manipulation.
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Liang-Yu, Yao, and 姚良瑜. "A study of Microchannel of Twin Swiss Roll Micromixer." Thesis, 2000. http://ndltd.ncl.edu.tw/handle/61675980532793973053.
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Yu-SinLin and 林雨欣. "Mixing of fluids in a corrugated micromixer with grooves." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/32538615875165171263.
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Wang, Yi-Chun, and 王毅軍. "DESIGN AND FABRICATION OF PASSIVE MICROMIXER ON CD PLATE." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/66766505168347643662.
Full textAbstract:
碩士大同大學
機械工程學系(所)
97
MEMS technology have been developed and applied in various kinds of fields, such as, optics, power, sensor, bioengineer and etc. However, with the improvement of quality of the life, people want to have better medical treatment. MEMS technology is applied by biotechnology such as PCR chip, detection chip, separated chip and etc. Effective and rapid mixing is essential to microfluidic systems. In this paper, MEMS technologies and hot embossing process are used to fabricate the micormixer on CD plate. In this research, CD is choose to be the base for passive micromixer constructed on, and fabricated by hot embossing technology. It can reduce the substrate cost, operating cost and stabilizing quality. Finally, this micromixer can obtained mixing purpose when the operating condition at the rotation speed is 2500rpm, in 20 seconds for color distribution and ph determination.
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Sie, Jing-yang, and 謝景揚. "Analyzing the performance of an active diverging-type micromixer." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/22485727413008315533.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
96
In this study, mixing performance of an active micromixer is investigated by numerical simulation and experiments. An active micromixer is comsisted of three sections: the T junction, the mixing section, and the outlet. Two parameters are explored: half angle of the mixing section and phase difference of the two sinusoidal pressure actuations. A diverging-type micromixer with a half angle of 25° is used in the numerical simulation. At the two inlets, time-varying sinusoidal pressures (amplitude 500 Pa, frequency 100 Hz) superimposed by a constant shift of 250 Pa are applied. From the numerical results, best mixing is achieved with a MI (mixing index) of 0.66 when the actuating pressures are anti-phase (phase difference π). On the contrary, in-phase actuation (phase difference 0) leads to poorest mixing. The evolutions of concentration profiles and flow fields reveal that fluid is stretched by a pair of circulations in the diverging region to enhance local mixing. Furthermore, fluid tends to flow from one inlet directly into the other when the actuating pressures are not inphase. The residual fluid in the opposite inlet is then pushed to the other side of the diverging region. This phenomenon helps to increase the contact area between the two fluids and mixing is improved significantly. At a phase difference of π, the unique circulation in the confluence region leads to three-dimensional helical flow so that best mixing is achieved. During the experiments, both flow visualization and mixing quantification are conducted. For the diverging-type micromixers, minimum CV (0.04) is accomplished at θ = 20° with a phase difference of 0.75π. For the converging-type micromixers, minimum CV (0.09) is accomplished at θ = -30° with a phase difference of 0.75π. Under dynamic pressure actuations, flow instability is observed for both straight and diverging-type micromixers. Since flow instability tends to enhance the fluid stretching and folding effects,mixing performance can be easily improved by alternating the geometry of the mixing section.
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Huang, Ker-Jer, and 黃科志. "Flow Mixing Mechanism in A Vortex-Modulation Grooved Micromixer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/14858390063972991346.
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Lin, Wen-Hsing, and 林文星. "Calculations and Analyses of Transient Flow Field in Micromixer." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/43635501556148623800.
Full textAbstract:
碩士國立成功大學
機械工程學系碩博士班
92
In the micro system, the mixing time of the different fluids is larger than or equal to its reaction time. In this situation, mixing and reaction is happening nearly synchronically. Thus, incomplete mixing would affects reaction velocity and the mixing effect of fluid molecules decides the overall system efficiency. Therefore, the micromixer is a very important sub-system in the microfluidic devices. In the macro scale flow field, we could produce the turbulence to advance the fluid mixing. However, we could not use the way that produces the turbulent flow to enhance the mixing effect in very small scale. The goal of this research is to make two or more different fluids have high mixing performance under the laminar flow condition in the period of time. This research uses Computational Fluid Dynamics method to simulate the transient flow field phenomenon and mixing effect in the passive micro mixer. This micro mixer is composed of a convergent nozzle, a mixing zone and feedback side-channels. The offset of the two feedback side-channels outlet derive vortexes to change position and magnitude. This phenomenon would enhance the mixing effect. In addition, we join the thin plates in this micro mixer and discuss the influence of the flow field and mixing efficiency. We collated the results of this research and provided the basic, important numerical computation data and analysis to the related researchers for references in the future.
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Wu, Hsin-Yu, and 吳新雨. "An Electrokinetic Micromixer for Micro-fluidic Bio-chip Application." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/00073189901251890467.
Full textAbstract:
碩士國立清華大學
動力機械工程學系
91
A novel microfluidic mixer based on periodically varying the ζ-potential on the microchannel walls through the field-effect control and asymmetric-herringbone electrode design has been developed and demonstrated successfully. In contrast to previous micromixer work from other groups, this micromixer does not need complex three-dimensional serpentine microstructure or external pumps to generate chaos-like flow. The influences of parameters such as pH value, ionic concentrations of the electrolyte, and radial electric field on the ζ-potential are discussed in thesis. They indicate that it is easier to modulate ζ-potential on the microchannel wall in the condition of a lower pH value and lower concentration of the buffer solution. The mathematical models for the influence of the nonuniform ζ-potential on the velocity profile, the volumetric flow rate, and the induced pressure distribution in a rectangular cross-section microchannel are also derived and show the mixing effect of varying ζ-potential. Numerical simulation results utilizing CFDRC show the good mixing efficiency for our micromixer design with asymmetric herringbone electrodes and periodic voltage control. The microfabrication process for our electrokinetic micromixer has been developed successfully. Via the quantitative analysis of Image Processing Toolbox in Matlab, experimental results successfully demonstrate a great mixing enhancement compared with diffusion effect only Our electrokinetic micromixer design can enhance the mixing effect by appropriate modulation of the ζ-potential, which results in manipulating local flow fields. The work reported here considers for the first time temporal/spatial ζ-potential modulation for microfluidic mixer applications.
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Wang, Ke-Chin, and 王克勤. "Design and Flow Simulation of a New Type Micromixer." Thesis, 2002. http://ndltd.ncl.edu.tw/handle/5grw3s.
Full textAbstract:
碩士國立成功大學
機械工程學系碩博士班
90
In micro-scale, complete mixing of two or more fluids within a reasonable time plays an important role in Micro-Total-Analysis-System recently. The applications of biomedical area are biomedical diagnose, gene expression analysis and drug discovery. However, in the macroscopic flow we know, we can increase the contact area of two different fluids by producing turbulence to enhance the mixing effect. But the flow velocity and length in micro-scale are smaller than those in macro-scale, and the Reynolds number in micro system is smaller than the turbulent Reynolds number. Therefore, the possibility of enhancing the mixing effects by producing turbulence, has been excluded. The objective of this study is to design a new type micromixer by using Computational Fluid Dynamics (CFD) techniques. The primary idea of this micromixer is to add feedback channels on the both sides of the main flow channel. Producing the mixing effect by using these feedback channels that guide the fluids flow back to the main channel. Analyze and simulate the flow of this micromixer, so that we can provide important design parameters for designers and the operation conditions for experimenters, which can bring about influences of mixing, likes geometry, channel position and inlet velocity.
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Liu, Hsin-Ping. "A Rapid Micromixer via 3D Counter-Rotating Circulatory Flow." 2008. http://www.cetd.com.tw/ec/thesisdetail.aspx?etdun=U0001-2607200814221200.
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Jiang, Li-Ren, and 江立人. "Design Optimization of Passive Micromixer on CD Microfluidic Device." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/2y42cb.
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碩士國立虎尾科技大學
機械與機電工程研究所
99
This paper presents the passive micromixer on a CD microfluidic chip that performs plasma mixing function. The driving force of CD microfluidic device including, the centrifugal force due to the system rotation, the Coriolis force as a function of the rotation angular frequency and velocity of liquid. In this study, a commercial software tool (COMSOL) was used for mixing analysis. We present a numerical investigation on mixing and flow structures in microchannels with different geometries: square-wave, curved and zig-zag. Numerical results show that the mixing index of square-wave micromixer is the best design in all three cases of micromixers. Therefore, the square-wave micromixer will be selected for optimization design. The SU-8 mold was first fabricated on the silicon substrate and the soft replica molding method used to fabricate the PDMS micromixer. Following the fabrication process, the PDMS micromixers were bonded to the microfluidic CD using oxygen plasma treatment technique. A series of numerical and experimental investigations were performed to analysis the mixing index of micromixers. The experimental results show that the mixing index exceeded in 90 % when the disk rotates at a speed of around 2000 rpm in 5 seconds.
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Hsu, Shih-chieh, and 徐士傑. "Dynamic Simulation,Optimal Design and Control of an Elecrtoosmosis Micromixer." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/50802344374286828896.
Full textAbstract:
碩士逢甲大學
化學工程學所
95
Abstract This thesis considers the dynamic simulation, optimal design and control of electroosmosis micromixer mixing processes. A finite element method is used to solve the systematic parameter to the influence of electroosmosis micromixer exit end concentration. In order to improve the efficiency of mixing dissipation and arrive anticipative concentration, a real code genetic algorithm along is applied for the optimal design of electroosmosis micromixer. For conversion regulation of electroosmosis micromixer, a direct adaptive model-free control scheme is proposed to regulate the exit end concentration. An output-bounded single neuron controller is utilized for the learning control of the process by merely observing the process output error, even though the process dynamics is characterized by partial differential equations. Extensive simulation results reveal that the proposed model-based control strategy is more superior to existing methodologies, such as IMC-PI and PI controls. From the significant results presented in this thesis, it is believed that the proposed optimal design and control strategies can substantially enhance the effectiveness and performance of electroosmosis micromixer mixing processes.
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Hung, Chi-Tsung, and 洪啟琮. "Design of the Electrophoresis Fluidic Micromixer with Electronic Control Modules." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/10353922361187731500.
Full textAbstract:
碩士逢甲大學
自動控制工程所
92
The microfluidic system with precision control and analysis has been applicated in many fields to promote life quality, especially in biochemical application. Based on MEMS technology and electrophoresis principle as well as high voltage power control interface design, a reliable miniaturized electrophoresis device is developed to have fast analysis, simple operation, and precision control. The miniaturized electrophoresis fluidic micromixer chip has been developed and realized after the fluidic and electrophoresis characteristic simulation using IntelliSuite. The chip of electrophoresis fluidic micromixer integrated microchannels and holes are fabricated by using laser photolithography. The control signal of electrophoresis fluidic micromixer chip comes from high voltage power control interface that provides optimal control effects in flow velocity, flow direction and mixture reaction. A CCD inspection unit has built for laser induced fluorescence detection. Thus, the miniaturized electrophoresis fluidic micromixer system consists of a high voltage power control interface, an electrophoresis fluidic micromixer chip and a photo image inspection unit. The miniaturized portable system fabricated with low cost can provide variety of operation function that developed in the research can be applied to obtain more biochemical experiment information in some clinical supporting research. The system also can apply in different measurement system to improve equipment automation.
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Chuang, Feng-Chao, and 莊豐兆. "Development of a Novel 3D Tesla Micromixer for Bio-Applications." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/5z648d.
Full textAbstract:
碩士國立臺北科技大學
能源與冷凍空調工程系碩士班
102
Microfluidic devices with multi-functional elements have been a highly promising tool to realize mixing, reaction, transport, separation, and detection of bio-samples on a single microchip for diverse applications in the biochemistry, biophysics and medical fields. The purpose of this research is to develop a μ-TAS (Miniaturized Total Analysis Systems, μ-TAS) for simple, fast and accurate detection of NSCLC (Non-Small Cell Lung Cancer, NSCLC) via an indicator of EGFR (Epidermal Growth Factor Receptor, EGFR) overexpression. The proposed system integrates a novel 3D Tesla micromixer with a microflow cytometer to achieve mixing and hydrodynamic focusing results in the downstream. Continuous fluid mixing and hydrodynamic focusing processes centralizes mixed sample cells/particles into a focusing stream to realize the purposes of sorting and detection. The computational fluid dynamics (CFD) method was also applied to determine the flow field, pressure drop and mixing efficiency of microfluidic chips for different Reynolds numbers. Numerical and experimental results have demonstrated the capability of the developed microfluidic device to realize a mixing index of 97% and to control the focused stream within an 18-μm width for detection of NSCLC through the indicator of EGFR overexpression.
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Tu, Chia-Ho, and 涂家和. "Design and analysis of a Lorentz-force-driven active micromixer." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/02496037897785676770.
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碩士國立清華大學
動力機械工程學系
97
The purpose of this thesis is to develop an active micromixer. The fluid is driven by Lorentz force which is induced by the coupling between a magnetic field in vertical direction and a current density due to ionic motions under an electric field. The deformation and distortion of the fluid interface enhance mixing. In this article, we simulated the mixing process by CFD-ACE+ and discussed different flow patterns under DC and AC driving signals, to help design the suitable space between two electrodes for the micromixer. In device fabrication, the electrodes were manufactured by MEMS techniques, and the chamber was made of PDMS by molding. Finally, we combined them with field-generated instruments. In experiment observation, we performed dye experiment and observed the mixing process by optical microscope. Results of the experiment were compared and discussed with the previous simulations. This research brings out a novel coiled pattern of electrode design. In addition, we utilized AC signal to reduce bubbles formation and erosion of electrodes. Thus, the device has a better performance. The advantages of this active micromixer are simplicity in its structure and fabrication process, great manipulation of fluid, without high voltage signal that gains side effects of specimens, and ability to integrate and control in electric circuits. Therefore, we hope the design concept of the micromixer could apply to biomedical detection, raising its speed and accuracy in the future.
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Lai, Cheng-Yu, and 賴政佑. "3-D Numerical Simulation on a Biosensor and a Micromixer." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/58887180307853711229.
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碩士國立臺灣大學
應用力學研究所
96
The working principle of immunoassays is based on the specific binding reaction of an analyte-ligand protein pair in physiological environments. It is a natural characteristic which is applied to design biosensors. In this work, we perform a three-dimensional (3-D) finite element simulation on the binding reaction kinetics of the common-used protein, C-reactive protein (CRP), in a reaction chamber (micro-channel) of a biosensor. Several crucial factors which influence the binding reaction in the simulation are discussed first, including the channel height, micro-channel with or without cavity, inlet flow velocity, and the dimensions, arrangement, and shape of the reaction surface. The flow velocity perpendicular to the reaction surface is so small that the analyte, which is supposed to bind to ligands on the reaction surface, is transported mainly by diffusion. The rate of the binding reaction on the reaction surface is usually large enough to restrain all analytes reaching there practically. Thus, the process is said to be diffusion-limited, and in order to increase the reaction rate, a technique is proposed to enhance the binding efficiency of immunoassay for a biosensor. By applying a non-uniform AC electric field to the flow in the micro-channel of the biosensor, the electrothermal force can be generated to induce a pair of vortices to stir the flow field. These swirling patterns in the fluid can accelerate the transport of the analyte to the reaction surface and hence enhance the association and dissociation of analyte-ligand complex. In this work, we design several types of biosensors with various arrangements of a pair of electrodes and the reaction surface to discuss the electrothermal effect on the binding reaction for a biosensor. For the arrangement of the biosensor we studied, the initial slope of the binding curve of the analyte-ligand complex versus time can be raised up to 4.09 times in association phase and 3.08 times in dissociation phase for CRP, respectively, under applying AC field of 15 peak-to-peak and operating frequency of 100 . Furthermore, by increasing the conductivity of the carrier solution and adding the thermal control on the walls of the micro-channel, we can accelerate the response of the binding reaction by applying a lower voltage. Based on these results, an improved design of the biosensor incorporating a pair of electrodes is demonstrated and the presented data of numerical simulation are useful in designing the biosensors. In addition, biochemical applications often require rapid mixing of different fluid samples. At the microscale level, the fluid flow is usually highly ordered laminar flow, and the lack of turbulence makes the diffusion be the primary mechanism for mixing. By applying a non-uniform AC electric field to the flow micro-channel, the electrothermal force can be generated to induce disturbance to the flow field and hence promote the mixing efficiency for the micromixer. A 3-D numerical investigation of an active micromixer, utilizing electrothermal effect to enhance its mixing efficiency, is proposed in this work. The numerical results show that a mixing quality of 84% can be achieved at the outlet of the micromixer.
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Shie, Shin-shian, and 謝新賢. "Analyzing the performance of an electroosmotically-actuated diverging-type micromixer." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/96040221824247849691.
Full textAbstract:
碩士國立臺灣科技大學
機械工程系
97
In this study, mixing performance of an electroosmotically-actuated diverging-type micromixer is investigated. Four parameters are explored: actuation mode, superimposed pressure head, half angle of the diverging section, and phase difference of the input voltages. From the flow visualization, the evolutions of concentration profiles reveal that there are two mixing mechanisms in the micromixer: the electroosmotic instability induced by electric potential gradient, and the flow lamination due to inverse flow between the two inlets. Since the electroosmotic instability depends on the magnitude of the potential gradient, bipolar actuation results in higher potential gradient, and hence better mixing performance. Furthermore, fluid tends to flow from one inlet directly into the other when the actuating voltages are not inphase. The residual fluid in the opposite inlet is then pushed to the other side of the diverging region and formed fluid striations. This lamination phenomenon helps to increase the contact area between the two fluids and mixing is improved. As the phase difference increases, both electroosmotic instability and fluid lamination are enhanced due to a longer duration that both mechanisms are in action. Nevertheless, antiphase leads to sequential injection of the working fluids. Lacking proper cross-stream mixing, mixing relatively is poor. Because electroosmotics results in very low Reynolds number in the micromixer, half angle plays a minor role in mixing performance here. To quantify mixing performance, time-averaged mixing efficiency is calculated. While increasing the imposed pressure head accelerates the flow and diminishes molecular diffusion, higher time-averaged mixing efficiency is obtained with a superimposed pressure head of 1 mm. Under unipolar actuation, a maximum time-averaged mixing efficiency of 0.65 is accomplished at θ = 50° with a phase difference of 0.75π. In contrast, under bipolar actuation, a maximum time-averaged mixing efficiency of 0.8 is achieved at θ = 0° with a phase difference of 0.5π.