Academic literature on the topic 'Immiscible liquid-liquid microfluidics'
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Journal articles on the topic "Immiscible liquid-liquid microfluidics"
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Du, Siqi, Shahab Shojaei-Zadeh, and German Drazer. "Liquid-based stationary phase for deterministic lateral displacement separation in microfluidics." Soft Matter 13, no. 41 (2017): 7649–56. http://dx.doi.org/10.1039/c7sm01510k.
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Zhang, Hong Bo, Jian Pu Liu, and Huan Xin Lai. "Numerical Simulation of Jetting Instability in Flow Focusing Microfluidics." Key Engineering Materials 609-610 (April 2014): 630–36. http://dx.doi.org/10.4028/www.scientific.net/kem.609-610.630.
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In this paper, jetting behavior of two immiscible liquids, water as the outer liquid and silicone oil as the inner liquid in typical flow focusing microchannels were numerically studied using VOF method. At low capillary number, uniform microdroplets were obtained by the absolute instability. With the increasing of fluid flow ratio, the jet is thinner and tends to break up further away the cross junction. The results showed that the flow rate ratio is the main factor that influences the microdroplet sizes, while the frequency of microdroplets formation can be controlled mainly by the surface tension when it is in the jetting regime.
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Chin, Jit Kai. "STUDY OF LIQUID-LIQUID SLUG BREAK UP MECHANISM IN A MICROCHANNEL T-JUNCTION AT VARIOUS MODIFIED WEBER NUMBER." IIUM Engineering Journal 12, no. 2 (October 18, 2011): 111–22. http://dx.doi.org/10.31436/iiumej.v12i2.70.
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The formation of immiscible liquid droplets, or slugs, in microchannels features the advantages of volume control and mixing enhancement over single-phase microflows. Although the applications of droplet-based microfluidics have been widely demonstrated, the fundamental physics governing droplet break-up remains an area of active research. This study defines an effective Weber (Weeff) number that characterizes the interplay of interfacial tension, shear stress and channel pressure drop in driving slug formation in T-junction microchannel for a relative range of low, intermediate and high flow rates. The immiscible fluid system in this study consists of Tetradecane slug formation in Acetonitrile. The progressive deformation of slug interfaces during break-up events is observed. Experimental results indicate that, at a relatively low Weeff, clean slug break-up occurs at the intersection of the side and main channels. At intermediate Weeff, the connecting neck of the dispersed phase is stretched to a short and thin trail of laminar flow prior to breaking up a short distance downstream of the T-junction. At a relatively high Weeff, the connecting neck develops into a longer and thicker trail of laminar flow that breaks up further downstream of the main channel.
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Soitu, Cristian, Alexander Feuerborn, Ann Na Tan, Henry Walker, Pat A. Walsh, Alfonso A. Castrejón-Pita, Peter R. Cook, and Edmond J. Walsh. "Microfluidic chambers using fluid walls for cell biology." Proceedings of the National Academy of Sciences 115, no. 26 (June 12, 2018): E5926—E5933. http://dx.doi.org/10.1073/pnas.1805449115.
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Many proofs of concept have demonstrated the potential of microfluidics in cell biology. However, the technology remains inaccessible to many biologists, as it often requires complex manufacturing facilities (such as soft lithography) and uses materials foreign to cell biology (such as polydimethylsiloxane). Here, we present a method for creating microfluidic environments by simply reshaping fluids on a substrate. For applications in cell biology, we use cell media on a virgin Petri dish overlaid with an immiscible fluorocarbon. A hydrophobic/fluorophilic stylus then reshapes the media into any pattern by creating liquid walls of fluorocarbon. Microfluidic arrangements suitable for cell culture are made in minutes using materials familiar to biologists. The versatility of the method is demonstrated by creating analogs of a common platform in cell biology, the microtiter plate. Using this vehicle, we demonstrate many manipulations required for cell culture and downstream analysis, including feeding, replating, cloning, cryopreservation, lysis plus RT-PCR, transfection plus genome editing, and fixation plus immunolabeling (when fluid walls are reconfigured during use). We also show that mammalian cells grow and respond to stimuli normally, and worm eggs develop into adults. This simple approach provides biologists with an entrée into microfluidics.
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Wang, Dumei, Dongtang Zhang, Yanan Wang, Guangsheng Guo, Xiayan Wang, and Yugang Sun. "Spontaneous Phase Segregation Enabling Clogging Aversion in Continuous Flow Microfluidic Synthesis of Nanocrystals Supported on Reduced Graphene Oxide." Nanomaterials 12, no. 23 (December 5, 2022): 4315. http://dx.doi.org/10.3390/nano12234315.
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Eliminating clogging in capillary tube reactors is critical but challenging for enabling continuous-flow microfluidic synthesis of nanoparticles. Creating immiscible segments in a microfluidic flow is a promising approach to maintaining a continuous flow in the microfluidic channel because the segments with low surface energy do not adsorb onto the internal wall of the microchannel. Herein we report the spontaneous self-agglomeration of reduced graphene oxide (rGO) nanosheets in polyol flow, which arises because the reduction of graphene oxide (GO) nanosheets by hot polyol changes the nanosheets from hydrophilic to hydrophobic. The agglomerated rGO nanosheets form immiscible solid segments in the polyol flow, realizing the liquid–solid segmented flow to enable clogging aversion in continuous-flow microfluidic synthesis. Simultaneous reduction of precursor species in hot polyol deposits nanocrystals uniformly dispersed on the rGO nanosheets even without surfactant. Cuprous oxide (Cu2O) nanocubes of varying edge lengths and ultrafine metal nanoparticles of platinum (Pt) and palladium (Pd) dispersed on rGO nanosheets have been continuously synthesized using the liquid–solid segmented flow microfluidic method, shedding light on the promise of microfluidic reactors in synthesizing functional nanomaterials.
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Villone, Massimiliano M., Janine K. Nunes, Yankai Li, Howard A. Stone, and Pier Luca Maffettone. "Design of a microfluidic device for the measurement of the elastic modulus of deformable particles." Soft Matter 15, no. 5 (2019): 880–89. http://dx.doi.org/10.1039/c8sm02272k.
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A microfluidic technique recently proposed in the literature to measure the interfacial tension between a liquid droplet and an immiscible suspending liquid [Hudson et al., Appl. Phys. Lett., 2005, 87, 081905], [Cabral and Hudson, Lab Chip, 2006, 6, 427] is suitably adapted to the characterization of the elastic modulus of soft particles in a continuous-flow process.
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D'Antona, Nicholas R., Paul A. Kempler, and Shannon W. Boettcher. "Co-Determination of the Kinetics and Stoichiometry of Electrochemical Ion Transfer at the Liquid-Liquid Interface." ECS Meeting Abstracts MA2022-01, no. 55 (July 7, 2022): 2246. http://dx.doi.org/10.1149/ma2022-01552246mtgabs.
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The desolvation of ions at electrochemical interfaces is widely accepted as being the rate limiting step to charge transfer in devices such as ion-intercalation batteries and electrolyzers. While activation energies can be obtained for processes like ion intercalation, the kinetics and mechanism of desolvation remain elusive because they are often convoluted with resistances arising from complex interfacial chemistries. Here I present the use of a biphasic microfluidic electrochemical cell to simultaneously study the kinetics and stoichiometry of tetrabutylammonium (TBA) ion transfer at the interface between two immiscible electrolyte solutions (ITIES). Ion transfer at the ITIES allows one to mostly eliminate the variable of complex interfacial chemistry in the process of desolvation, and with our flow cell geometry we can separate the two phases after ion transfer to measure reaction products via quantitative nuclear magnetic resonance spectroscopy (qNMR). Thus, our novel microfluidic platform for studying electrochemical ion transfer allows us to correlate desolvation kinetics with ion-solvent shell identity, and eventually inform the design of ion transfer mediators/catalysts for the improvement of energy storage technology. Figure 1
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Gómez, J. R., J. P. Escandón, C. G. Hernández, R. O. Vargas, and D. A. Torres. "Multilayer analysis of immiscible power-law fluids under magnetohydrodynamic and pressure-driven effects in a microchannel." Physica Scripta 96, no. 12 (November 18, 2021): 125028. http://dx.doi.org/10.1088/1402-4896/ac37a0.
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Abstract In the present study, the combined magnetohydrodynamic and pressure-driven flow of multilayer immiscible fluids into a parallel flat plate microchannel is semi-analytically solved. Due to the handling of complex fluids in various microfluidic platform applications, the fluid transport reviewed here considers the power-law model. The movement of electrically conductive fluid layers is due to Lorentz forces that arise from the interaction between an electric current and a magnetic field. To find a solution for the flow field, the momentum equation and the rheological model for each fluid layer, together with the corresponding boundary conditions at the liquid-liquid and solid-liquid interfaces, are solved simultaneously through a closed system of nonlinear equations. The graphical results show the influence of the dimensionless parameters that arise from the mathematical modeling on the velocity profiles and flow rate. These are the magnetic parameters, the fluid layers thickness, the viscosity coefficients, the ratios between pressure forces and magnetic forces, and the flow behavior indexes. This theoretical work contributes to the design of microfluidic devices for flow-focusing tasks in chemical, clinical, and biological areas.
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Li, Chao, David J. Niles, Duane S. Juang, Joshua M. Lang, and David J. Beebe. "Automated System for Small-Population Single-Particle Processing Enabled by Exclusive Liquid Repellency." SLAS TECHNOLOGY: Translating Life Sciences Innovation 24, no. 6 (June 10, 2019): 535–42. http://dx.doi.org/10.1177/2472630319853219.
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Exclusive liquid repellency (ELR) describes an extreme wettability phenomenon in which a liquid phase droplet is completely repelled from a solid phase when exposed to a secondary immiscible liquid phase. Earlier, we developed a multi-liquid-phase open microfluidic (or underoil) system based on ELR to facilitate rare-cell culture and single-cell processing. The ELR system can allow for the handling of small volumes of liquid droplets with ultra-low sample loss and biofouling, which makes it an attractive platform for biological applications that require lossless manipulation of rare cellular samples (especially for a limited sample size in the range of a few hundred to a few thousand cells). Here, we report an automated platform using ELR microdrops for single-particle (or single-cell) isolation, identification, and retrieval. This was accomplished via the combined use of a robotic liquid handler, an automated microscopic imaging system, and real-time image-processing software for single-particle identification. The automated ELR technique enables rapid, hands-free, and robust isolation of microdrop-encapsulated rare cellular samples.
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Hattori, Shohei, Chenghe Tang, Daiki Tanaka, Dong Hyun Yoon, Yoshito Nozaki, Hiroyuki Fujita, Takashiro Akitsu, Tetsushi Sekiguchi, and Shuichi Shoji. "Development of Microdroplet Generation Method for Organic Solvents Used in Chemical Synthesis." Molecules 25, no. 22 (November 17, 2020): 5360. http://dx.doi.org/10.3390/molecules25225360.
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Recently, chemical operations with microfluidic devices, especially droplet-based operations, have attracted considerable attention because they can provide an isolated small-volume reaction field. However, analysis of these operations has been limited mostly to aqueous-phase reactions in water droplets due to device material restrictions. In this study, we have successfully demonstrated droplet formation of five common organic solvents frequently used in chemical synthesis by using a simple silicon/glass-based microfluidic device. When an immiscible liquid with surfactant was used as the continuous phase, the organic solvent formed droplets similar to water-in-oil droplets in the device. In contrast to conventional microfluidic devices composed of resins, which are susceptible to swelling in organic solvents, the developed microfluidic device did not undergo swelling owing to the high chemical resistance of the constituent materials. Therefore, the device has potential applications for various chemical reactions involving organic solvents. Furthermore, this droplet generation device enabled control of droplet size by adjusting the liquid flow rate. The droplet generation method proposed in this work will contribute to the study of organic reactions in microdroplets and will be useful for evaluating scaling effects in various chemical reactions.
Dissertations / Theses on the topic "Immiscible liquid-liquid microfluidics"
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Lee, Hyundo. "Immiscible liquid-liquid displacement in microfluidic channels : effects of wettability and geometry." Thesis, Massachusetts Institute of Technology, 2017. http://hdl.handle.net/1721.1/113544.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Mechanical Engineering, 2017.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 153-174).
Displacement of a fluid by an immiscible fluid occurs in various situations such as oil recovery in underground reservoirs, transport in the human body, and other interconnected network systems and porous media. We are motivated by oil recovery processes in geological porous media that take place at the micrometer scale, and focus in particular on the effects of wettability and geometry of microstructures on immiscible liquid-liquid displacements, that result from interactions in oil-water-rock systems. Microfluidic devices, micromodels, have been proposed as experimental test beds for reproducing flows in oil reservoirs in laboratory environments since they offer fine control over geometry and chemistry, and therefore provide insights into their effects on the process. These microfluidic devices are usually two-dimensional and transparent, with a simplified porous network designed to visualize and study fluid behavior in porous media. In oil reservoir research, the microfluidic test beds reflect underground oil reservoir conditions, for example, porosity, permeability, and wettability. The work in this thesis focuses on simple, additive micromodel fabrication techniques to build robust and reproducible structures in microfluidic channels and on the basic and fundamental understanding of immiscible displacement processes with simplified models and controlled flow conditions. We introduce two simple micromodel fabrication methods that can provide design flexibility with photopatterning, the ability to tailor wetting properties, and the calcium carbonate structure that is the most common constituent of oil reservoirs. We utilize a microscope projection lithography to construct polymeric structures with pre-defined wetting properties using a UV-initiated copolymerization method, and we are also able to make real-rock carbonate micromodels by incorporating calcium carbonate seed particles into microstructures and growing them with a supersaturated calcium carbonate solution. Using the micromodel fabrication methods thus developed, we have systematically explored oil-water immiscible displacement processes in a controlled manner with respect to various geometric and wettability conditions. With the fact that our flow experiment is in a small capillary number regime, we formulate a mathematical model for the oil-water displacement process with photopatterned structures of simple geometry and periodic patterns, and verify our theoretical model by matching it with our experimental observations, and we also conduct oil recovery model studies with encapsulated oil pockets with aqueous surfactant solution flooding. Lastly, based on the experience of calcium carbonate/hydrogel composite structuring and calcium carbonate growth from the structure, we expand our work and develop a method of making drug-laden hydrogel particles. By developing flexible methods to make microfluidic devices for immiscible fluids displacement study and investigation on the displacement process, we have been able to realize that microfluidic research with simplified conditions can enhance fundamental understanding of multiphase flow in natural, complex porous media.
by Hyundo Lee.
Ph. D.
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Elekaei, Behjati Hamideh. "Study of immiscible liquid-liquid microfluidic flow using SPH-based explicit numerical simulation." Thesis, 2016. http://hdl.handle.net/2440/102887.
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Microfluidic devices are utilized in a wide range of applications, including micro-electromechanical devices, drug delivery, biological diagnostics and micro-fuel cell systems. Of particular interest here are liquid-liquid microfluidic systems; which are used in drug discovery, food and oil industry amongst others. Increased understanding of the fundamentals of flows in such devices and an improved capacity to design them can come from modelling. In the case of liquid-liquid flows in microfluidic systems, it is necessary to explicitly model the behaviour of the individual liquid phases. Such explicit numerical simulation (ENS) as it is termed requires advanced numerical methods that are able to evaluate flow involving multiple deforming fluid domains within often complex boundaries. Smoothed Particle Hydrodynamics (SPH), a Lagrangian meshless method, is particularly suitable for such problems. This use of a CFD allows determination of parameters that are difficult to determine experimentally because of the challenges faced in microfabrication. The study reported in this thesis addresses these concerns through development of a new SPH-based model to correctly capture the immiscible liquid-liquid interfaces in general and for a microfluidic hydrodynamic focusing system in particular. The model includes surface tension to enforce immiscibility between different liquids based on a new immiscibility model, enforces strict incompressibility, and allows for arbitrary fluid constitutive models. This work presents a detailed study on the effects of various flow parameters including flowrate ratio, viscosity ratio and capillary number of each liquid phase, and geometry characteristics such as channel size, width ratio, and the angle between the inlet main and side channels on the flow dynamics and topological changes of the multiphase microfluidic system. According to our findings, both flowrate quantity and flowrate ratio affect the droplet length in the dripping regime and a large viscosity ratio imposes an increase in the flowrate of the continuous phase with the same capillary number of the dispersed phase to attain dripping regime in the outlet channel. Also, increasing the side channel width causes longer droplets, and the right-angled design makes the most efficient focusing behaviour. This study will provide great insights in designing microfluidic devices involving immiscible liquid-liquid flows.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Chemical Engineering, 2016.
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Lee, Jacky Sai Ho. "The analysis of electroosmotic flow in microfluidic channels with immiscible liquid-fluid interfaces." 2006. http://link.library.utoronto.ca/eir/EIRdetail.cfm?Resources__ID=442087&T=F.
Full textBooks on the topic "Immiscible liquid-liquid microfluidics"
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Lee, Jacky Sai Ho. The analysis of electroosmotic flow in microfluidic channels with immiscible liquid-fluid interfaces. 2006.
Find full textBook chapters on the topic "Immiscible liquid-liquid microfluidics"
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Li, Yujie, Jie Wang, Shijie Wang, Di Li, Shan Song, Peng Zhang, Jianguo Li, and Hai Yuan. "Immiscible Two-Phase Parallel Microflow and Its Applications in Fabricating Micro- and Nanomaterials." In Process Analysis, Design, and Intensification in Microfluidics and Chemical Engineering, 136–66. IGI Global, 2019. http://dx.doi.org/10.4018/978-1-5225-7138-4.ch005.
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The immiscible two-phase flow behaves nonlinearly, and it is a challenging task to control and stabilize the liquid-liquid interface. Parallel flow forms under a proper balance between the driving force, the friction resistance, and the interfacial tension. The liquid-solid interaction as well as the liquid-liquid interaction plays an important role in manipulating the liquid-liquid interface. With vacuum-driven flow, long and stable parallel flow is possible to be obtained in oil-water systems and can be used for fabricating micro- and nanomaterials. Ultra-small Cu nanoparticles of 4~10 nm were synthesized continuously through chemical reactions taking place on the interface. This makes it possible for in situ synthesis of conductive nanoink avoiding oxidation. Well-controlled interface reactions can also be used to produce ultra-long sub-micro Cu wires up to 10 mm at room temperature. This method provided new and simple additive fabrication methods for making integrated microfluidic devices.
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Li, Yujie, Jie Wang, Shijie Wang, Di Li, Shan Song, Peng Zhang, Jianguo Li, and Hai Yuan. "Immiscible Two-Phase Parallel Microflow and Its Applications in Fabricating Micro- and Nanomaterials." In Research Anthology on Synthesis, Characterization, and Applications of Nanomaterials, 200–224. IGI Global, 2021. http://dx.doi.org/10.4018/978-1-7998-8591-7.ch009.
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The immiscible two-phase flow behaves nonlinearly, and it is a challenging task to control and stabilize the liquid-liquid interface. Parallel flow forms under a proper balance between the driving force, the friction resistance, and the interfacial tension. The liquid-solid interaction as well as the liquid-liquid interaction plays an important role in manipulating the liquid-liquid interface. With vacuum-driven flow, long and stable parallel flow is possible to be obtained in oil-water systems and can be used for fabricating micro- and nanomaterials. Ultra-small Cu nanoparticles of 4~10 nm were synthesized continuously through chemical reactions taking place on the interface. This makes it possible for in situ synthesis of conductive nanoink avoiding oxidation. Well-controlled interface reactions can also be used to produce ultra-long sub-micro Cu wires up to 10 mm at room temperature. This method provided new and simple additive fabrication methods for making integrated microfluidic devices.
Conference papers on the topic "Immiscible liquid-liquid microfluidics"
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Moon, Hyejin, Praveen Kunchala, Yasith Nanayakkara, and Daniel W. Armstrong. "Liquid-Liquid Extraction Based on Digital Microfluidics." In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82268.
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Liquid-liquid extraction techniques are one of the major tools in chemical engineering, analytical chemistry, and biology, especially in a system where two immiscible liquids have an interface solutes exchange between the two liquid phases along the interface up to a point where the concentration ratios in the two liquids reach their equilibrium values [1]. In this paper, we propose to use room temperature ionic liquid (RTIL) as a second liquid phase for extraction, which forms immiscible interface with aqueous solutions. We demonstrate liquid-liquid extraction with the EWOD digital microfluidic device, two model extraction systems were tested. One is organic dye extracted from RTIL(1-butyl-3-methylimidazolium bis(trifluoromethanesulfonylimide or BMIMNTf2) to water and the other is iodine (I2) extracted from water to BMIMNTf2. Droplets of aqueous solution and BMIMNTf2 solution were generated on chip reservoir then transported for extraction and separated by EWOD actuation successfully.
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Kunchala, Praveen, Hyejin Moon, Yasith Nanayakkara, and Daniel W. Armstrong. "EWOD Based Liquid-Liquid Extraction and Separation." In ASME 2009 Summer Bioengineering Conference. American Society of Mechanical Engineers, 2009. http://dx.doi.org/10.1115/sbc2009-206690.
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Liquid-liquid extraction techniques are one of the major tools in chemical engineering, analytical chemistry, and biology, especially in a system where two immiscible liquids have an interface solutes exchange between the two liquid phases along the interface up to a point where the concentration ratios in the two liquids reach their equilibrium values [1]. Solutes including nucleic acids and proteins of interests can be extracted from one liquid phase to the other immiscible liquid phase as a preparation step for many analytical processes. There are several advantages in miniaturizing the liquid-liquid extraction methods to on-chip level extraction. Usual advantages of miniaturization are the reduction in the sample size and portability. In addition, transport phenomena is faster in Micro-systems than in ordinary size systems, and therefore, one may expect that liquid-liquid extraction takes less time to achieve in miniaturized devices. It is due to shorter diffusion time in micro scale as well as high surface to volume ratio of Microsystems. Electrowetting on dielectric (EWOD) digital microfluidics is an efficient platform to process droplet based analytical processes [2]. Nanoliter (nL) or smaller volume of aqueous liquid droplets can be generated and transported on a chip by EWOD process. In addition to the high surface to volume ratio, high chemical potential can be expected in droplet based extraction when the droplets are in motion. In this paper, we propose to use room temperature ionic liquid (RTIL) as a second liquid phase for extraction, which forms immiscible interface with aqueous solutions. Properties of RTIL can be tailored by choice of cation, anion and substituents. RTIL has been investigated as replacements for the organic solvents and various “task-specific” ionic liquid are being developed which exhibit many attractive properties such as very low vapor pressure, high thermal stability [3]. We recently published EWOD properties of various RTILs toward microfluidic applications [4]. To demonstrate liquid-liquid micro extraction on chip, we fabricated and tested EWOD digital microfluidic devices. Fig. 1 shows (a) top and (b) cross sectional views of EWOD device. Two model extraction systems were tested. One is organic dye extracted from RTIL (1-butyl-3-methylimidazolium bis(trifluoromethanesulfonylimide or BMIMNTf2) to water and the other is iodine (I2) extracted from water to BMIMNTf2. The later model experiment is demonstrated in Fig. 2. Droplets of aqueous solution and BMIMNTf2 solution were generated on chip reservoir then transported for extraction and separated by EWOD actuation. When an aqueous solution and BMIMNTf2 solution join together, they created an interface, since water and BMIMNTf2 are immiscible. Extraction of I2 was done along the interface. After successful extraction, two immiscible liquid phases were separated by EWOD actuation and formed two separate droplets. From the result shown in Fig 2 (g), it is expected that extraction performance at the interface of moving droplet would be enhanced compared to the stationary droplet, because a moving interface prevent the chemical equilibrium, thus more chemical extraction potential can be provided with a moving interface than at a stationary interface. This demonstration is the first step toward total analysis system. The presented result opens the way to on-chip micro extraction, which will be readily integrated with other sample preparation microfluidic components and detection components. Currently, micro extraction systems for larger molecules such as nucleic acids, proteins and biological cells are being developed for further analytical applications.
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Shibata, Yuichi, Kota Takamine, and Masahiro Kawaji. "Emission of Liquid Droplets From the Interface of Bidrops Pulled by a Ferrofluid in a Microchannel." In ASME 2009 7th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2009. http://dx.doi.org/10.1115/icnmm2009-82174.
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The field of microfluidics is developing with advances in biotechnology and μ-TAS technologies. In various devices, controlling the flow rate of liquid or gas accurately at micro or nanoliter volume levels is required. By using a ferrofluid, the flow of a liquid or gas in a microchannel can be controlled by the driving power exerted on the ferrofluid. In a previous study, an unsteady flow of a liquid slug caused by the driving force exerted by the ferrofluid was investigated in a 200μm circular microchannel. The velocity of the ferrofluid was found to be affected by the physical properties of the liquids being pulled, such as the dynamic and static contact angles, surface tension and kinematic viscosity of the liquid slugs. At sufficiently high velocities of the ferrofluid, emission of a liquid droplet from the liquid-liquid interface was observed. In the present study, combinations of various liquids with the ferrofluid were examined in two microchannels (130μm and 200μm diameter). The relationship between the emission of liquid droplets and interfacial fluctuation of the bidrops was investigated experimentally and analytically. The emission of liquid droplets from the interface and behavior of the interface were observed using liquids of different viscosities. The interfacial shape changed continuously until a liquid droplet was emitted from the interface of the immiscible liquids. When the ferrofluid velocity was increased, necking of the liquid-liquid interface occurred continuously and some liquid droplets were emitted from the interface. We could study the characteristics of emission of liquid droplets from the interfacial variation.
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Motosuke, Masahiro, Asami Hoshi, and Shinji Honami. "Photothermal Marangoni Convection for the Usage of Characterized Droplet Manipulation in Microfluidic Chip." In ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73304.
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Droplet-based microfluidics which involves discrete volumes with the use of immiscible phases enable controlled and rapid mixing inside the droplet and promoted reaction of reagents or cells. It can be operated as “digital fluidic platform.” Due to high surface area to volume ratio of transport phenomena in microscale, an interfacial behavior becomes more predominant than continuous-flow-based microfluidics. In this study, we have investigated an interfacial flow control based on local photothermal excitation of the interfacial tension gradient resulting in Marangoni convection for droplet manipulation in a microfluidic chip. The surface Marangoni flow occurs by the local thermal gradient induced by the localized light irradiation which is spatially characterized by a mask with a specific aperture geometry. In controlled droplet generation and manipulation, oil-in-water (O/W) system, oleic acid as the dispersed phase, were used in the present experiments. Droplets have volumes from 0.5 to 65 pL, corresponding to diameters from 10 to 50 μm. A microfluidic chip consists of two PDMS (polydimethylsiloxiane) channel layers fabricated using the softlithography. Spatially characterized heating is produced by a DPSS laser with a wavelength of 532 nanometers, a mask with aperture and a reduced-projection exposure optics. The light irradiation generates local temperature change in the continuous phase which can cause interfacial tension gradient when droplets come to the illuminated area. As a result, the droplet experiences a repulsion force from the illuminated area with high temperature because the liquid-liquid interface in this case has positive temperature dependence on the tension. The droplet can be trapped in the microchannel when U- or V-shaped light pattern is irradiated. When a light pattern with nozzle-like geometry is irradiated, droplets were focused toward the exit of the nozzle avoiding the irradiated area. The performances of the trapping and focusing of droplets due to the optically-induced interfacial flow were evaluated through behaviors of droplets with different sizes and light powers. The estimation of forces acting on a drop due to the photothermal Marangoni convection was also conducted.
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McCarthy, Conor E., Tara Dalton, and Mark Davies. "A Gravity Driven Microfluidic Platform for DNA Enrichment." In ASME 2013 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/imece2013-64599.
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There is currently considerable interest in the development of microfluidic based lab-on-chip devices for sample preparation in next generation sequencing. One of these steps is DNA enrichment which often relies on conventional PCR to amplify the sample to detectable levels. To successfully automate this step, technologies are required whereby the samples are selectively inputted, thermocycled and selectively dispensed, all non invasively and therefore leading to no contamination issues. In this study such a system was created through the use of liquid-liquid plugs flowing in a gravity driven siphon. Plug generation was achieved through an innovative approach whereby a hydrophobic tube was traversed between two immiscible fluids (silicon oil and PCR reagents) and successful amplification was shown for Beta-2-Microfloblin (B2M).
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Narayanan, Venkat R. T., Jianbo Li, Jeffrey D. Zahn, and Hao Lin. "Numerical Modeling of Microfluidic Two-Phase Electrohydrodynamic Instability." In ASME 2008 International Mechanical Engineering Congress and Exposition. ASMEDC, 2008. http://dx.doi.org/10.1115/imece2008-67757.
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Organic-aqueous liquid (phenol) extraction is one of many standard techniques to efficiently purify DNA directly from cells. Effective dispersion of one fluid phase in the other increases the surface area over which biological component partitioning may occur, and hence enhances DNA extraction efficiency. Electrohydrodynamic (EHD) instability can be harnessed to achieve this goal and has been experimentally demonstrated by one of the co-authors (JDZ). In this work, analysis and simulation are combined to study two-phase EHD instability. In the problem configuration, the organic (phenol) phase flows into the microchannel in parallel with and sandwiched between two aqueous streams, creating a three-layer planar geometry; the two liquid phases are immiscible. An electric field is applied to induce instability and to break the organic stream into droplets. The Taylor-Melcher leaky-dielectric model is employed to investigate this phenomenon. A linear analysis is carried out with a Chebyshev pseudo-spectral method, whereas a fully nonlinear numerical simulation is implemented using a finite volume, immersed boundary method (IBM). The results from both models compare favorably with each other. The linear analysis reveals basic instability characteristics such as kink and sausage modes. On the other hand, the nonlinear simulation predicts surface deformation in the strongly nonlinear regime pertinent to droplet formation. These numerical tools will be used to investigate the effects of the applied electric field, geometry, and convective flow rate on mixing and dispersion. The eventual objective is to maximize surface area of the organic phase under given experimental conditions for optimized DNA extraction.
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Gómez, Juan R., and Juan P. Escandón. "Combined Magnetohydrodynamic/Pressure Driven Flow of Multi-Layer Pseudoplastic Fluids Through a Parallel Flat Plates Microchannel." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86676.
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With the advance of microfluidic platforms and due to the need to solve different implications that still exist on the transport of electrically conducting fluids, the analysis on strategies in micropumps that involve a simplicity in its structure, absence of mechanical moving parts, flow reversibility and low power requirement is current. Therefore, the present investigation contributes with the analysis of the combined magnetohydrodynamic/pressure driven flow of multilayer immiscible fluids in a microchannel formed by two parallel flat plates. The mathematical model is based in a steady fully developed flow and the pumped fluids follow the power law model to describe the pseudoplastic fluids rheology, while magnetic effects on the flow are given from the Lorentz forces. The velocity profiles and flow rate are obtained in the limit of small Hartmann numbers by solving analytically a closed system of ordinary differential equations, together to the corresponding boundary conditions at the solid-liquid interfaces in the channel walls and at the liquid-liquid interfaces between the fluid layers. The results show that the flow field is controlled by the dimensionless parameters that arise from the mathematical modeling being a parameter that indicates the competition between pressure to the magnetic forces, magnetic parameters related to Hartmann numbers, viscosities ratios between the fluids, flow behavior indexes and the dimensionless position of the liquid-liquid interfaces.
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Pathak, Manabendra. "Computational Investigation of Microdroplet Formation in a Crossflow Membrane Emulsification Process." In ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2011. http://dx.doi.org/10.1115/icnmm2011-58033.
Full textAbstract:
Monodisperse microdroplets are formed, when a liquid is injected through a micropore into another immiscible liquid. Depending on the relative flow between the two phases, droplets may form in quiescent, coflowing and crossflowing environment. The dispersions of one phase liquid in another crossflowing liquid are observed in liquid emulsification process and the system has been used extensively in microfluidic devices to produce monodisperse microdroplets with controllable size. Liquid emulsions are widely used in food, cosmetics, pharmaceutics and polymer industries. In the present work, microdroplet formation in a crossflow membrane emulsification process has been investigated computationally using VOF/finite volume method. The full transient simulation has been carried out starting from the injection of dispersed phase to breakup into drops for different values of dispersed phase and continuous phase flow rate, surface tension and viscosity ratio of both the phases. Depending upon the values of the both phases, the droplet formation process shows the dripping and jetting behavior. The qualitative features of the two regimes and their transition have been correlated with different non-dimensional numbers such as Capillary number, Weber number and viscosity ratio of the two phase liquids. Some interesting nonlinear behavior such as period doubling been observed near the transition between the dripping and jetting regimes has. The topological characteristics of dripping, jetting and transition regimes in membrane emulsification have been observed different than in the cases of T-junction emulsification and flow focusing emulsification. Two ways of dripping to jetting transition have been observed, one with the increasing dispersed phase flow rate at constant continuous phase flow rate and other way is reducing the surface tension at constant dispersed phase flow rate. The effect of inertia force has been observed negligible for high value of surface tension and significant for lower surface tension value.
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Wu, Liang L., Wei Xu, Mark Bachman, and Guann-Pynn Li. "Passive Generation of Droplets in Mini and Microchannels." In ASME 2007 5th International Conference on Nanochannels, Microchannels, and Minichannels. ASMEDC, 2007. http://dx.doi.org/10.1115/icnmm2007-30227.
Full textAbstract:
Microfluidic systems generating droplets by oil and aqueous solutions have shown great promise in biochemical and chemical applications, each drop acting as a micro reaction vessel. A popular approach utilizes dual flow of immiscible fluids in microchannels, producing droplets by shear forces at the liquid interfaces. These systems require precise, computer controlled flow, and the resulting drops continue to move, and so are hard to localize. We have developed a unique method to generate an array of precision microdroplets on a plate that does not require careful fluid control and places the drops at specific, predetermined locations. The method utilizes geometric design of a channel to introduce instabilities in a column of water at predetermined locations with predetermined volumes ranging from a few nanoliters to microliters. Droplets form as a result of channel design, not as a result of fluid flow. Different drops can be set up at different locations and volume, then fused together to initiate a reaction. These micro-droplet arrays can be set up by hand in under one minute and can be used for high throughput or combinatorial experiments.