Journal articles: '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.

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Ting, Chue Cui, Afiq Mohd Laziz, Khoa Dang Dang Bui, Ngoc Thi Nhu Nguyen, Pha Ngoc Bui, Khoa Ta Dang, An Si Xuan Nguyen, Ngon Trung Hoang, Ku Zilati Ku Shaari, and Hoàng Huy Phước Lợi Phạm. "Hydrodynamic studies on liquid-liquid two phase flow separation in microchannel by computational fluid dynamic modelling." Science & Technology Development Journal - Engineering and Technology 4, no. 2 (May 4, 2021): first. http://dx.doi.org/10.32508/stdjet.v4i2.810.

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Microfluidic systems undergo rapid expansion of its application in different industries over the few decades as its surface tension-dominated property provides better mixing and improves mass transfer between two immiscible liquids. Synthesis of biodiesel via transesterification of vegetable oil and methanol in microfluidic systems by droplet flow requires separation of the products after the reaction occurred. The separation technique for multiphase fluid flow in the microfluidic system is different from the macro-system, as the gravitational force is overtaken by surface force. To understand these phenomena completely, a study on the hydrodynamic characteristics of two-phase oil-methanol system in microchannel was carried out. A multiphase Volume of Fluid model was developed to predict the fluid flow in the microchannel. An inline separator design was proposed along with its variable to obtain effective separation for the oil-methanol system. The separation performance was evaluated based on the amount of oil recovered and its purity. The capability of the developed model has been validated through a comparison of simulation results with published experiment. It was predicted that the purity of recovered oil was increased by more than 46% when the design with side openings arranged at both sides of the microchannel. The highest percentage recovery of oil from the mixture was simulated at 91.3% by adding the number of side openings to ensure the maximum recovery. The oil that was separated by the inline separator was predicted to be at 100% purity, which indicates that no methanol contamination throughout the separation process. The purity of the separated product can be increased by manipulating the pressure drop across the side openings. Hence, it can be concluded that the separation in a large diameter microchannel system is possible and methodology can be tuned to achieve the separation goal. Finally, the simulation results showed that the present volume of fluid model had a good agreement with the published experiment.

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Chowdhury, Imdad Uddin, Pallab Sinha Mahapatra, and Ashis Kumar Sen. "A wettability pattern-mediated trapped bubble removal from a horizontal liquid–liquid interface." Physics of Fluids 34, no. 4 (April 2022): 042109. http://dx.doi.org/10.1063/5.0086149.

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The passage of a bubble through an immiscible horizontal liquid–liquid interface has a wide range of applications, from chemical processes to microfluidic devices. Buoyancy governs this passage of the bubble, and at the liquid–liquid interface, the bubble encounters a downward pulling force due to surface tension. Depending on the volume of the bubble, it may pass through or become trapped at the interface. In this study, for the first time, we proposed the idea of trapped bubble removal from a liquid–liquid interface with the aid of a wettability-patterned cone. The bubble detachment dynamic is investigated using numerical results and theoretical analysis. The effect of fluid properties and cone parameters on bubble detachment has been extensively studied. It is found that density contrast ( ρr) and viscosity contrast ( μr) of both the liquids, surface tension ratio ( σr), bubble diameter ( d0), wettability of the cone ( θ), and cone angle ( α) play a crucial role in bubble detachment. Here, we studied the effect of each parameter on the bubble detachment and, based on that, identified two distinct regimes, e.g., detached regime and non-detached regime. The regime map is represented by two non-dimensional groups βco and ψ, which are functions of Bond number ( Bo), Ohnesorge number ( Oh), α, and θ. Furthermore, the transport characteristics of the bubble on the cone after the detachment indicate that the bubble velocity decreased as it moved from the narrower to the wider section of the cone. These findings could be useful in the removal of trapped bubbles from a liquid–liquid interface in small-scale chemical industries.

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Avendaño, Jorge, Nicolle Lima, Antonio Quevedo, and Marcio Carvalho. "Effect of Surface Wettability on Immiscible Displacement in a Microfluidic Porous Media." Energies 12, no. 4 (February 19, 2019): 664. http://dx.doi.org/10.3390/en12040664.

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Wettability has a dramatic impact on fluid displacement in porous media. The pore level physics of one liquid being displaced by another is a strong function of the wetting characteristics of the channel walls. However, the quantification of the effect is still not clear. Conflicting data have shown that in some oil displacement experiments in rocks, the volume of trapped oil falls as the porous media becomes less water-wet, while in some microfluidic experiments the volume of residual oil is higher in oil-wet media. The reasons for this discrepancy are not fully understood. In this study, we analyzed oil displacement by water injection in two microfluidic porous media with different wettability characteristics that had capillaries with constrictions. The resulting oil ganglia size distribution at the end of water injection was quantified by image processing. The results show that in the oil-wet porous media, the displacement front was more uniform and the final volume of remaining oil was smaller, with a much smaller number of large oil ganglia and a larger number of small oil ganglia, when compared to the water-wet media.

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Escandón, Juan P., David A. Torres, Clara G. Hernández, Juan R. Gómez, and René O. Vargas. "Transient Analysis of the Electro-Osmotic Flow of Multilayer Immiscible Maxwell Fluids in an Annular Microchannel." Colloids and Interfaces 6, no. 4 (October 24, 2022): 60. http://dx.doi.org/10.3390/colloids6040060.

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This work investigates the transient multilayer electro-osmotic flow of viscoelastic fluids through an annular microchannel. The dimensionless mathematical model of multilayer flow is integrated by the linearized Poisson-Boltzmann equation, the Cauchy momentum equation, the rheological Maxwell model, initial conditions, and the electrostatic and hydrodynamic boundary conditions at liquid-liquid and solid-liquid interfaces. Although the main force that drives the movement of fluids is due to electrokinetic effects, a pressure gradient can also be added to the flow. The semi-analytical solution for the electric potential distribution and velocity profiles considers analytical techniques as the Laplace transform method, with numerical procedures using the inverse matrix method for linear algebraic equations and the concentrated matrix exponential method for the inversion of the Laplace transform. The results presented for velocity profiles and velocity tracking at the transient regime reveal an interesting oscillatory behavior that depends on elastic fluid properties via relaxation times. The time required for the flow to reach steady-state is highly dependent on the viscosity ratios and the dimensionless relaxation times. In addition, the influence of other dimensionless parameters on the flow as the electrokinetic parameters, zeta potentials at the walls, permittivity ratios, ratio of pressure forces to electro-osmotic forces, number of fluid layers, and annular thickness are investigated. The findings of this study have significant implications for the precise control of parallel fluid transport in microfluidic devices for flow-focusing applications.

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Forget, M., M. O'Donnell, and M. Davies. "Characterization of a liquid bridge microdroplet dispenser for use in molecular diagnosis." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 222, no. 5 (May 1, 2008): 777–86. http://dx.doi.org/10.1243/09544062jmes712.

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Microfluidic solutions offer the possibility of minimizing time-to-result, reagents and labour costs of molecular diagnosis, while improving their quality and accuracy. The use of droplets as microreactors represents one of the points of focus of this research. The current paper presents a geometry, referred to as a ‘two-way liquid bridge’, for dispensing microdroplets upstream of a nucleid acid amplifier. A single continuous phase, drawn through a capillary tube, can be automatically segmented into droplets of a predetermined size, with each droplet separated from its nearest neighbour and the wetted surface by an immiscible phase. The device has many advantages over previously reported segmenters. An experimental study, conducted in an adjustable device, demonstrates the effect of geometric parameters on the volume of fluid dispensed. Based on these experimental observations, a quasi-empirical theory is proposed to predict the dispensed volume for a given range of dispensed volumes, which is then demonstrated to work as a first-order design tool.

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Shen, Yao, Bo Chen, Han Zuilhof, and Teris A. van Beek. "Microfluidic Chip-Based Induced Phase Separation Extraction as a Fast and Efficient Miniaturized Sample Preparation Method." Molecules 26, no. 1 (December 23, 2020): 38. http://dx.doi.org/10.3390/molecules26010038.

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Induced phase separation extraction (IPSE) is an efficient sample clean-up technique that can replace liquid-liquid extraction (LLE). The purpose of this study was to miniaturize IPSE by carrying it out in a microfluidic chip. An IPSE chip was designed and evaluated for its ability to separate and purify samples on a microscale. The 5 × 2 cm chip was fed with a solution of polar to non-polar model compounds in acetonitrile-water (1:1). In the 100 µm wide and 40 µm deep microchannels, the sample solution was efficiently separated into two immiscible phases by adding a hydrophobic solvent as inducer. Analytes present in the sample solution each migrated to their own favorable phase upon phase separation. After optimization, extraction and fractionation were easily and efficiently achieved. The behavior of analytes with a pH-dependent partitioning could be influenced by adjusting the pH of the sample solution. Scutellaria baicalensis extract, used in Traditional Chinese Medicine (TCM), was successfully separated in aglycones and glycosides. In this microscale system, the sample and solvent consumption is reduced to microliters, while the time needed for the sample pretreatment is less than one minute. Additionally, the extraction efficiency can reach up to 98.8%, and emulsion formation is avoided.

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Raad, Mohammad, Sajad Rezazadeh, Habib Jalili, and Davod Abbasinezhad Fallah. "A numerical study of droplet splitting in branched T-shaped microchannel using the two-phase level-set method." Advances in Mechanical Engineering 13, no. 11 (November 2021): 168781402110454. http://dx.doi.org/10.1177/16878140211045487.

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Droplet splitting as a significant feature of droplet-based microfluidic systems has been widely employed in biotechnology, biomedical engineering, tissue engineering, and it has been preferred over continuous flow systems. In the present paper, two-dimensional numerical simulations have been done to examine the asymmetrical droplet splitting process. The two-phase level set method (LSM) has been predicted to analyze the mechanism of droplet formation and droplet splitting in immiscible liquid/liquid two-phase flow in the branched T-junction microchannel. Governing equations on flow field have been discretized and solved using finite element-based COMSOL Multiphysics software (version 5.3a). Obtained numerical results were validated by experimental data reported in the literature which show acceptable agreement. The model was developed to simulate the mechanism of droplet splitting at the branched T-junction microchannel. This study provides a passive technique to asymmetrically split up microdroplets at the downstream T-junctions. The results show that outlet branches’ pressure gradient affects the droplet splitting. Specifically, it has been shown that the splitting ratio increases by increasing the length ratio, and equal droplet splitting can be achieved where the ratio is LL/ Lu = 1. We have used two outlet branches having the same width but different lengths to create the required pressure gradient. As the length ratio of the outlet branches increases, the diameter ratio increases as well.

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Chaabene, Nesrine, Kieu NGO, Mireille Turmine, and Vincent Vivier. "Ionic Liquid Membraneless Redox Flow Battery." ECS Meeting Abstracts MA2022-01, no. 48 (July 7, 2022): 2040. http://dx.doi.org/10.1149/ma2022-01482040mtgabs.

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Today, ionic liquids are more and more present in many fields and more particularly in electrochemistry. Indeed, their physical and chemical properties are appealing and attractive. They are conductive solvents in which organic and inorganic salts can be dissolved depending on the nature of the anion and cation that make up the ionic liquid. However, only very few studies have reported their use in membraneless redox flow batteries (RFBs) for the storage of renewable energy 1, 2. The concept of membraneless redox-flow batteries was first reported by Ferrigno et al.3 in 2002, with the development of a millimeter-scale redox fuel cell based on the vanadium aqueous electrolyte solutions. In this work, we have developed an ionic liquid membraneless RFB by using 1-ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide (C2mimTFSI) as supporting electrolyte and Quinone (Q) and iron chloride (FeCl2) as electroactive species in a microfluidic system. Polarization curve and cyclic voltammetry were used to characterize the electrochemical properties as well as the performance of the microbattery. The proof-of-concept of the system has been shown with an open circuit potential of 0.6 V, obtained with both polarization curve and cyclic voltammetry, and with a current density ranging from 0.3 to 0.65 mA cm-2 for total flow rates of 10 to 20 µL min-1. As shown on fig. 1(b), a maximum of power of 40 µW cm-2 has been obtained. Such a technology is promising and performances can be enhanced by using 3D electrodes and optimizing the choice of the redox mediators (concentration, potential, etc.) Figure 1: (a) Experimental set-up and polarization curves of the cell for a total flow rate of (b) 20 µL.min-1 References 1. Navalpotro, P.; Palma, J.; Anderson, M.; Marcilla, R., A Membrane-Free Redox Flow Battery with Two Immiscible Redox Electrolytes. Angew. Chem. Int. Ed. Engl. 2017, 56 (41), 12460-12465. 2. Chen, R.; Bresser, D.; Saraf, M.; Gerlach, P.; Balducci, A.; Kunz, S.; Schroder, D.; Passerini, S.; Chen, J., A Comparative Review of Electrolytes for Organic-Material-Based Energy-Storage Devices Employing Solid Electrodes and Redox Fluids. ChemSusChem 2020, 13 (9), 2205-2219. 3. Ferrigno, R.; Stroock, A. D.; Clark, T. D.; Mayer, M.; Whitesides, G. M., Membraneless vanadium redox fuel cell using laminar flow. Journal of the American Chemical Society 2002, 124 (44), 12930-12931. Figure 1

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Kovalchuk, Nina M., and Mark J. H. Simmons. "Effect of Surfactant Dynamics on Flow Patterns Inside Drops Moving in Rectangular Microfluidic Channels." Colloids and Interfaces 5, no. 3 (August 2, 2021): 40. http://dx.doi.org/10.3390/colloids5030040.

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Drops contained in an immiscible liquid phase are attractive as microreactors, enabling sound statistical analysis of reactions performed on ensembles of samples in a microfluidic device. Many applications have specific requirements for the values of local shear stress inside the drops and, thus, knowledge of the flow field is required. This is complicated in commonly used rectangular channels by the flow of the continuous phase in the corners, which also affects the flow inside the drops. In addition, a number of chemical species are present inside the drops, of which some may be surface-active. This work presents a novel experimental study of the flow fields of drops moving in a rectangular microfluidic channel when a surfactant is added to the dispersed phase. Four surfactants with different surface activities are used. Flow fields are measured using Ghost Particle Velocimetry, carried out at different channel depths to account for the 3-D flow structure. It is shown that the effect of the surfactant depends on the characteristic adsorption time. For fast-equilibrating surfactants with a characteristic time scale of adsorption that is much smaller than the characteristic time of surface deformation, this effect is related only to the decrease in interfacial tension, and can be accounted for by the change in capillary number. For slowly equilibrating surfactants, Marangoni stresses accelerate the corner flow, which changes the flow patterns inside the drop considerably.

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Doppler, Diandra, Mohammad T. Rabbani, Romain Letrun, Jorvani Cruz Villarreal, Dai Hyun Kim, Sahir Gandhi, Ana Egatz-Gomez, et al. "Co-flow injection for serial crystallography at X-ray free-electron lasers." Journal of Applied Crystallography 55, no. 1 (February 1, 2022): 1–13. http://dx.doi.org/10.1107/s1600576721011079.

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Serial femtosecond crystallography (SFX) is a powerful technique that exploits X-ray free-electron lasers to determine the structure of macromolecules at room temperature. Despite the impressive exposition of structural details with this novel crystallographic approach, the methods currently available to introduce crystals into the path of the X-ray beam sometimes exhibit serious drawbacks. Samples requiring liquid injection of crystal slurries consume large quantities of crystals (at times up to a gram of protein per data set), may not be compatible with vacuum configurations on beamlines or provide a high background due to additional sheathing liquids present during the injection. Proposed and characterized here is the use of an immiscible inert oil phase to supplement the flow of sample in a hybrid microfluidic 3D-printed co-flow device. Co-flow generation is reported with sample and oil phases flowing in parallel, resulting in stable injection conditions for two different resin materials experimentally. A numerical model is presented that adequately predicts these flow-rate conditions. The co-flow generating devices reduce crystal clogging effects, have the potential to conserve protein crystal samples up to 95% and will allow degradation-free light-induced time-resolved SFX.

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Asl, Yousef Abdossalami, Yadollah Yamini, and Shahram Seidi. "Development of a microfluidic-chip system for liquid–phase microextraction based on two immiscible organic solvents for the extraction and preconcentration of some hormonal drugs." Talanta 160 (November 2016): 592–99. http://dx.doi.org/10.1016/j.talanta.2016.07.063.

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Chen, Delai L., Liang Li, Sebastian Reyes, David N. Adamson, and Rustem F. Ismagilov. "Using Three-Phase Flow of Immiscible Liquids To Prevent Coalescence of Droplets in Microfluidic Channels: Criteria To Identify the Third Liquid and Validation with Protein Crystallization." Langmuir 23, no. 4 (February 2007): 2255–60. http://dx.doi.org/10.1021/la062152z.

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Gómez López, Juan Rolando, Clara Guadalupe Hernández Roblero, Juan Pablo Escandón Colin, and René Osvaldo Vargas Aguilar. "Viscous micropump of immiscible fluids using magnetohydrodynamic effects and a power-law conducting fluid." Revista Mexicana de Física 67, no. 6 Nov-Dec (October 4, 2021). http://dx.doi.org/10.31349/revmexfis.67.060601.

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Small-scale fluid transport methods have grown significantly in recent years, mainly in applications in microfluidic systems. Therefore, the present study analyzes the movement of two-layers of immiscible fluids within a parallel flat plates microchannel. The fluid layers are composed of a Newtonian fluid and a power-law fluid. The pumping is produced by magnetohydrodynamics effects that act on the non-Newtonian conducting fluid dragging the non-conducting Newtonian fluid by viscous forces. Under the consideration of a laminar, incompressible, and unidirectional flow, the dimensionless mathematical model is established by the momentum equations for each fluid, together with the corresponding boundary conditions at solid-liquid and liquid-liquid interfaces. The problem formulation is semi-analytically solved using the Newton-Raphson method. The results are presented as a function of the velocity profiles and flow rate, showing interesting behaviors that depend on the physical and electrical properties of each fluid and flow conditions via the dimensionless parameters such as the flow behavior index, a magnetic parameter related to Lorenz forces, the fluids viscosity ratios and the dimensionless liquid-liquid interface position. This work contributes to the understanding of the various immiscible non-conducting fluids pumping techniques that can be used in microdevices.

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Gómez López, Juan Rolando, Clara Guadalupe Hernández Roblero, Juan Pablo Escandón Colin, and René Osvaldo Vargas Aguilar. "Viscous micropump of immiscible fluids using magnetohydrodynamic effects and a power-law conducting fluid." Revista Mexicana de Física 67, no. 6 Nov-Dec (October 4, 2021). http://dx.doi.org/10.31349/revmexfis.67.060601.

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Small-scale fluid transport methods have grown significantly in recent years, mainly in applications in microfluidic systems. Therefore, the present study analyzes the movement of two-layers of immiscible fluids within a parallel flat plates microchannel. The fluid layers are composed of a Newtonian fluid and a power-law fluid. The pumping is produced by magnetohydrodynamics effects that act on the non-Newtonian conducting fluid dragging the non-conducting Newtonian fluid by viscous forces. Under the consideration of a laminar, incompressible, and unidirectional flow, the dimensionless mathematical model is established by the momentum equations for each fluid, together with the corresponding boundary conditions at solid-liquid and liquid-liquid interfaces. The problem formulation is semi-analytically solved using the Newton-Raphson method. The results are presented as a function of the velocity profiles and flow rate, showing interesting behaviors that depend on the physical and electrical properties of each fluid and flow conditions via the dimensionless parameters such as the flow behavior index, a magnetic parameter related to Lorenz forces, the fluids viscosity ratios and the dimensionless liquid-liquid interface position. This work contributes to the understanding of the various immiscible non-conducting fluids pumping techniques that can be used in microdevices.

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Zhang, Haipeng, and Sangjin Ryu. "Drop Generation in Cross-Flow of Liquid Rotating in Rigid Body Motion." Journal of Fluids Engineering 142, no. 10 (June 26, 2020). http://dx.doi.org/10.1115/1.4047411.

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Abstract Various methods have been developed to generate monodisperse drops of a dispersed phase (DP) liquid in an immiscible continuous phase (CP) liquid, which include the membrane emulsification method and the microfluidic drop generation. This study proposes an easy-to-adopt drop generation method using cross-flow: a DP liquid is injected through a stationary vertical syringe needle into a CP liquid rotating in rigid body motion. The developed method was tested and characterized using de-ionized water as the DP liquid and mineral oil as the CP liquid. Drops were generated mainly either in the dripping mode or the jetting mode, and the former resulted in higher monodispersity. Smaller drops were generated when a thinner syringe needle was used, the average flow speed of the DP liquid through the needle was decreased, or the linear flow speed of the CP liquid at the needle location was increased. Especially, the power–law relationship was observed between the drop diameter and the flow speeds, and the dripping-to-jetting transition (DJT) was observed when the Weber number of the DP liquid was about 5.

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Echelmeier, Austin, Jorvani Cruz Villarreal, Marc Messerschmidt, Daihyun Kim, Jesse D. Coe, Darren Thifault, Sabine Botha, et al. "Segmented flow generator for serial crystallography at the European X-ray free electron laser." Nature Communications 11, no. 1 (September 9, 2020). http://dx.doi.org/10.1038/s41467-020-18156-7.

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Abstract Serial femtosecond crystallography (SFX) with X-ray free electron lasers (XFELs) allows structure determination of membrane proteins and time-resolved crystallography. Common liquid sample delivery continuously jets the protein crystal suspension into the path of the XFEL, wasting a vast amount of sample due to the pulsed nature of all current XFEL sources. The European XFEL (EuXFEL) delivers femtosecond (fs) X-ray pulses in trains spaced 100 ms apart whereas pulses within trains are currently separated by 889 ns. Therefore, continuous sample delivery via fast jets wastes >99% of sample. Here, we introduce a microfluidic device delivering crystal laden droplets segmented with an immiscible oil reducing sample waste and demonstrate droplet injection at the EuXFEL compatible with high pressure liquid delivery of an SFX experiment. While achieving ~60% reduction in sample waste, we determine the structure of the enzyme 3-deoxy-D-manno-octulosonate-8-phosphate synthase from microcrystals delivered in droplets revealing distinct structural features not previously reported.

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Nassar, Omar, Mazin Jouda, Michael Rapp, Dario Mager, Jan G. Korvink, and Neil MacKinnon. "Integrated impedance sensing of liquid sample plug flow enables automated high throughput NMR spectroscopy." Microsystems & Nanoengineering 7, no. 1 (April 14, 2021). http://dx.doi.org/10.1038/s41378-021-00253-2.

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AbstractA novel approach for automated high throughput NMR spectroscopy with improved mass-sensitivity is accomplished by integrating microfluidic technologies and micro-NMR resonators. A flow system is utilized to transport a sample of interest from outside the NMR magnet through the NMR detector, circumventing the relatively vast dead volume in the supplying tube by loading a series of individual sample plugs separated by an immiscible fluid. This dual-phase flow demands a real-time robust sensing system to track the sample position and velocities and synchronize the NMR acquisition. In this contribution, we describe an NMR probe head that possesses a microfluidic system featuring: (i) a micro saddle coil for NMR spectroscopy and (ii) a pair of interdigitated capacitive sensors flanking the NMR detector for continuous position and velocity monitoring of the plugs with respect to the NMR detector. The system was successfully tested for automating flow-based measurement in a 500 MHz NMR system, enabling high resolution spectroscopy and NMR sensitivity of 2.18 nmol s1/2 with the flow sensors in operation. The flow sensors featured sensitivity to an absolute difference of 0.2 in relative permittivity, enabling distinction between most common solvents. It was demonstrated that a fully automated NMR measurement of nine individual 120 μL samples could be done within 3.6 min or effectively 15.3 s per sample.

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Escandón, Juan P., Juan R. Gómez, and Clara G. Hernández. "Multilayer Analysis of Phan-Thien-Tanner Immiscible Fluids Under Electro-Osmotic and Pressure-Driven Effects in a Slit Microchannel." Journal of Fluids Engineering 142, no. 6 (March 5, 2020). http://dx.doi.org/10.1115/1.4046375.

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Abstract Because the pumping of samples by viscous drag forces and the use of flow-focusing for several sheath flows are widely used in microfluidic devices applications, the present investigation treats about the transport of multilayer immiscible viscoelastic fluids into a slit microchannel by electro-osmotic and pressure-driven effects. The mathematical formulation for the steady-state analysis of the flow field is based on the Poisson–Boltzmann equation and the Cauchy momentum equation. Each fluid layer has independent physical and electrical properties and is formed by a mixture of an electrolyte with a fluid that provides a viscoelastic behavior that follows the simplified Phan-Thien-Tanner (sPTT) rheological model. In the problem, the fluids are conductive and the walls of the microchannel are dielectrics, yielding electric double layers in the liquid–liquid and solid–liquid interfaces; therefore, the flow field is controlled by interfacial electrostatic conditions. The semi-analytical results are centered in the description of the velocity profiles and in the flowrate as a function of a series of dimensionless parameters arising from the mathematical modeling, where we can observe that the multilayer flow characteristics are related to the type of electrolyte solutions, since when the flow field is formed by two or more, interesting interfacial effects appear that modify the shape of velocity profiles and change the magnitude of flowrate in favor or against, depending of the positions of each fluid layer; in addition, the flow raises or diminishes by applying an external pressure gradient.

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Mottin, Donatien, Tsaihsing Martin Ho, and Peichun Amy Tsai. "Upscaling production of droplets and magnetic particles with additive manufacturing." Rapid Prototyping Journal ahead-of-print, ahead-of-print (August 17, 2021). http://dx.doi.org/10.1108/rpj-12-2020-0320.

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Purpose Monodisperse microfluidic emulsions – droplets in another immiscible liquid – are beneficial to various technological applications in analytical chemistry, material and chemical engineering, biology and medicine. Upscaling the mass production of micron-sized monodisperse emulsions, however, has been a challenge because of the complexity and technical difficulty of fabricating or upscaling three-dimensional (3 D) microfluidic structures on a chip. Therefore, the authors develop a fluid dynamical design that uses a standard and straightforward 3 D printer for the mass production of monodisperse droplets. Design/methodology/approach The authors combine additive manufacturing, fluid dynamical design and suitable surface treatment to create an easy-to-fabricate device for the upscaling production of monodisperse emulsions. Considering hydrodynamic networks and associated flow resistance, the authors adapt microfluidic flow-focusing junctions to produce (water-in-oil) emulsions in parallel in one integrated fluidic device, under suitable flow rates and channel sizes. Findings The device consists of 32 droplet-makers in parallel and is capable of mass-producing 14 L/day of monodisperse emulsions. This convenient method can produce 50,000 millimetric droplets per hour. Finally, the authors extend the current 3 D printed fluidics with the generated emulsions to synthesize magnetic microspheres. Originality/value Combining additive manufacturing and hydrodynamical concepts and designs, the authors experimentally demonstrate a facile method of upscaling the production of useful monodisperse emulsions. The design and approach will be beneficial for mass productions of smart and functional microfluidic materials useful in a myriad of applications.

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Wang, Chao, Weilin Zhong, Suqing Peng, Jingtao Zhang, Riyang Shu, Zhipeng Tian, Qingbin Song, and Ying Chen. "Robust Hydrogen Production via Pickering Interfacial Catalytic Photoreforming of n-Octanol-Water Biphasic System." Frontiers in Chemistry 9 (July 22, 2021). http://dx.doi.org/10.3389/fchem.2021.712453.

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Pickering emulsion offers a promising platform for conducting interfacial reactions between immiscible reagents; it is particularly suitable for hydrogen production by photoreforming of non-water soluble biomass liquid and water. Herein, Pt-promoted (001)-facet-dominated anatase TiO2 nanosheets were synthesized by a hydrothermal route associated with microfluidic technology for high activity and metal dispersion, and selective surface modification was carried out for preparing Janus particles. Photoreforming hydrogen production through n-octanol and water that formed O/W microemulsion with an average diameter of 540 µm was achieved to obtain amphiphilic catalyst. The as-prepared 2D Janus-type catalysts exhibited remarkably stable emulsification performance as well as photocatalytic activity. This finding indicates that triethoxyfluorosilane had negligible impact on the catalytic performance, yet provided a remarkable benefit to large specific surface area at microemulsion interface, thereby enhancing the H2 yield up to 2003 μmol/g. The cyclic experiments indicate that the decrease in cyclic performance was more likely to be caused by the coalescence of the microemulsion rather than the decrease in catalytic activity, and the microemulsion could be easily recovered by simply hand shaking to more than 96% of the initial performance.

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Journal articles on the topic 'Immiscible liquid-liquid microfluidics'

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