scholarly journals Diamagnetic Manipulation of Cell-Encapsulating Droplets

2021 ◽  
Author(s):  
Stephanie Buryk-Iggers
Keyword(s):  
Magnetic Field ◽  
Flow Rate ◽  
Continuous Phase ◽  
Phase Flow ◽  
Label Free ◽  
Flow Focusing ◽  
Precise Control ◽  
Prostate Cells ◽  
The Magnetic Field ◽  
Droplet Phase

In this thesis, a microfluidic method for label-free control of cell encapsulating droplets is developed using diamagnetic forces. To generate droplets in a microfluidic device, we use a symmetrical flow-focusing design, where two streams of a continuous phase shear a single stream of a droplet phase, resulting in droplet generation. First, it is shown that by adjusting only the droplet phase flow rate, precise control of empty droplets can be achieved. Human prostate cells are then introduced to the system and encapsulated by droplets. Control of the cell-encapsulated droplets and empty droplets is studied. It is shown that cell-encapsulated droplets and empty droplets deflect by different amounts when exposed to the magnetic field. By exploiting this difference, efficient sorting of empty droplets from cell-encapsulated droplets is achieved at a purity of 85% in a single pass. Following sorting, cells are analyzed and show 90% viability after a two-hour incubation period.

scholarly journals Diamagnetic Manipulation of Cell-Encapsulating Droplets

2021 ◽  
Author(s):  
Stephanie Buryk-Iggers
Keyword(s):  
Magnetic Field ◽  
Flow Rate ◽  
Continuous Phase ◽  
Phase Flow ◽  
Label Free ◽  
Flow Focusing ◽  
Precise Control ◽  
Prostate Cells ◽  
The Magnetic Field ◽  
Droplet Phase

In this thesis, a microfluidic method for label-free control of cell encapsulating droplets is developed using diamagnetic forces. To generate droplets in a microfluidic device, we use a symmetrical flow-focusing design, where two streams of a continuous phase shear a single stream of a droplet phase, resulting in droplet generation. First, it is shown that by adjusting only the droplet phase flow rate, precise control of empty droplets can be achieved. Human prostate cells are then introduced to the system and encapsulated by droplets. Control of the cell-encapsulated droplets and empty droplets is studied. It is shown that cell-encapsulated droplets and empty droplets deflect by different amounts when exposed to the magnetic field. By exploiting this difference, efficient sorting of empty droplets from cell-encapsulated droplets is achieved at a purity of 85% in a single pass. Following sorting, cells are analyzed and show 90% viability after a two-hour incubation period.

scholarly journals Prediction Models of Droplet Characteristics Based on the Locally Convergent Configurations in PMMA Microchips

2021 ◽  
Vol 2097 (1) ◽  
pp. 012027
Author(s):  
Zhongxin Liu ◽  
Zhiliang Wang ◽  
Chao Wang ◽  
Jinsong Zhang
Keyword(s):  
Flow Rate ◽  
Relative Position ◽  
Prediction Models ◽  
Continuous Phase ◽  
Lubricating Oil ◽  
Flow Rate Ratio ◽  
Phase Flow ◽  
Exponential Relationship ◽  
Two Phase ◽  
Relationship Of

Abstract This paper novel designed the local convergence configuration in the coaxial channels to study the two-phase flow (lubricating oil (continuous phase, flow rate Q c)/deionized water (dispersed phase, flow rate Q d)). Two geometric control variables, the relative position (x) and tapering characteristics (α), had the different effects on the droplet formation. The increase of relative position x caused the higher frequency and finer droplets, and the increase of convergence angle α, took the opposite effects. The results indicated that the equivalent dimensionless droplet length Ld/Wout and the flow rate ratio Qd/Qc had an exponential relationship of about 1/2. Similarly, it was found that the dispersed droplets generating frequency and the two-phase capillary number, CaTP = uTPμc/σ, had an exponential relationship. The advantage of the convergent configurations in micro-channel was the size and efficiency of droplet generation was very favorable to be controlled by α and x.

scholarly journals Experimental Study on the Effect of Locally Convergent Configurations on the Flow Pattern in PMMA Microchips

2021 ◽  
Vol 2097 (1) ◽  
pp. 012006
Author(s):  
Jinsong Zhang ◽  
Zhongxin Liu ◽  
Chao Wang ◽  
Zhiliang Wang
Keyword(s):  
Flow Rate ◽  
Rectangular Cross Section ◽  
Continuous Phase ◽  
Lubricating Oil ◽  
Phase Flow ◽  
Two Phase ◽  
Convergence Angle ◽  
Syringe Needle ◽  
Micro Flow ◽  
Two Parameters

Abstract The geometries of micro-channel play a key role in forming of digital droplets, and can be real-time or effective controlling methodologies. Local convergence regions are designed in the rectangular cross-section channels on PMMA microchips, in which two-phase coaxial jets are introduced by inserting a syringe needle. The two-phase flow (lubricating oil (continuous phase, flow rate Q c)/deionized water (dispersed phase, flow rate Q d)) is considered. Two geometric control variables, the relative position (needle displacement x) and tapering characteristics (convergence angle α), are naturally adopted to discribe such geometry configurations. The micro-flow under the change of these two parameters is mainly studied in this paper. Four kinds of characteristic flow patterns, namely, sausages, slug, dripping and jetting, are found in the experiment, and their occurring parameters and developing dynamic characteristics are discussed. The experiment shows that the increase of inner needle displacement x can produce higher frequency and finer droplets, which is in consistent with our previous results obtained in round tube experiments and simulations. While increasing the convergence angle α, contrarily, takes opposite effects.

scholarly journals The Use of Chemical Methods and Magnetic Field in Conditioning and Dewatering of Digested Sewage Sludge

Water ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 1642
Author(s):  
Tomasz Kamizela ◽  
Mariusz Kowalczyk ◽  
Iwona Zawieja
Keyword(s):  
Magnetic Field ◽  
Flow Rate ◽  
Chemical Method ◽  
Solid Phase ◽  
Cake Filtration ◽  
Mechanical Destruction ◽  
Sludge Flocs ◽  
Flow Through ◽  
Sludge Conditioning ◽  
The Magnetic Field

This study verified the possibility of sludge conditioning before dewatering using a combination of factors such as iron coagulant, polyelectrolyte, and the magnetic field generated by a solenoid. It was assumed that further conditioning with the magnetic field, leads to the formation of a rigid structure of sludge flocs by the destabilized and flocculated solid phase particles in the sludge (using the conditioning dual chemical method: PIX—polyelectrolyte). The resulting structure can increase the efficiency of sludge cake filtration by reducing sludge compressibility and maintaining the porosity necessary for the flow of removed water through the filter cake. The effects of the exposure of conditioned sludge (after the dual chemical method) to the magnetic field depended on two factors. The first factor was the direction of sludge flow through the magnetic field. This was a key factor in improving the efficiency of sludge conditioning using this method. The sludge flow through the solenoid in the direction opposite to the magnetic field had a strong effect on the particles. The second factor was the rate of sludge flow through the magnetic field. Better results were obtained for a flow rate of 1.0 L/min than for pumping sludge through a coil at a rate of 2.0 L/min. At a flow rate of 1.0 L/min, the exposure time of the sludge to the magnetic field was 6.6 s. Too high a flow rate may lead to the deterioration of filtration efficiency by adverse changes in the structure of sludge flocs. This may be due to the mechanical destruction of the flocs structure of sludge by a too turbulent flow.

Parametric Study of Droplet Formation and Characteristics Within Microfluidic Devices — A Case Study

2020 ◽  
Vol 12 (07) ◽  
pp. 2050077
Author(s):  
Seyedeh Sarah Salehi ◽  
Amir Shamloo ◽  
Siamak Kazemzadeh Hannani
Keyword(s):  
Interfacial Tension ◽  
Physical Properties ◽  
Flow Rate ◽  
Viscosity Ratio ◽  
Droplet Formation ◽  
Continuous Phase ◽  
Phase Flow ◽  
Phase Density ◽  
Size And Shape ◽  
The Impact

Droplet-based microfluidics technologies hold great attention in a wide range of applications, including chemical analysis, drug screening, and food industries. This work aimed to describe the effects of different physical properties of the two immiscible phases on droplet formation in a flow-focusing microfluidic device and determining proper flow rates to form a droplet within the desired size range. A numerical model was developed to solve the governing equations of two-phase flow and the results were validated with previous experimental results. The results demonstrate different types of droplet formation regimes from dripping to jetting and different production rates of droplets as a consequence of the impact of each property on fluid flow, including the viscosity ratio, density, interfacial tension, and the flow rate ratio. Based on the results, flow rate, viscosity, and interfacial tension strongly affect the droplet formation regime as well as its size and shape. Droplet diameter increases by increasing the dispersed to continuous phase flow rate as well as the interfacial tension while it decreases by increasing the viscosity ratio and the continuous phase density. Moreover, the formation of satellite droplets was modeled, and the effect of interfacial tension, the viscosity of the dispersed phase and the continuous phase density were found to be important on the conditions that the satellite droplets are suppressed. Since the formation of the satellite droplets induces polydispersity in droplet size, this phenomenon is avoided. Collectively, choosing appropriate aqueous and oil phases with proper physical properties is crucial in forming monodisperse droplets with defined size and shape.

Numerical Study on Bubble Formation in a Microchannel Flow-Focusing Device Using the VOF Method

2011 ◽  
Author(s):  
Shobeir Aliasghar Zadeh ◽  
Rolf Radespiel
Keyword(s):  
Surface Tension ◽  
Disperse Phase ◽  
Flow Rate ◽  
Capillary Number ◽  
Bubble Formation ◽  
Continuous Phase ◽  
Glycerol Solution ◽  
Flow Focusing ◽  
Injection Angle ◽  
Bubble Length

The liquid-gas two-phase flow in a flow-focusing device are numerically investigated and the results are compared with experimental data. The geometries and the structured meshes were generated using the Gridgen software, while the computations were conducted with Fluent. N2 (disperse phase) and Water-Glycerol solution (continuous phase) at standard atmospheric conditions are considered as fluids. Based on dimensional analysis, the effects of various parameters such as the flow rates of both phases (effect of CQ = Qd/Qc), the viscosities of both phases (effect of the respective Reynolds number Re), the surface tension (effect of the capillary number) and the geometrical properties of the channel (channel width W and injection angle β) on the bubble formation and its length are compared to available experimental results. The break-up mechanism of the bubbles in various capillary regimes is explained. The computed length of the generated bubbles as a function of the capillary number (varying the flow rate of the continuous phase) are in good agreement with the experiments. Further studies indicate that at a constant flow rate of the continuous phase, the bubble length rises strongly as the flow rate of the disperse phase increases. In contrast, the relative effects of the viscosity and the surface tension on the length of the bubbles are moderate. The numerical results using various injection angles show that the bubble length increases, as the injection angle is raised from β = 45° to β = 90°.

Possible Use of Magnetic Fields in Determining Pore Geometry of Porous Media

1971 ◽  
Vol 11 (03) ◽  
pp. 223-228 ◽  
Author(s):  
C.I. Pierce ◽  
L.C. Headley ◽  
W.K. Sawyer
Keyword(s):  
Magnetic Field ◽  
Porous Media ◽  
Magnetic Fields ◽  
Transverse Magnetic Field ◽  
Field Intensity ◽  
Flow Rate ◽  
Transverse Magnetic ◽  
Conducting Fluid ◽  
Petroleum Reservoir ◽  
The Magnetic Field

Abstract Simplified models, consisting of single, circular channels and channels of different length and diameter in series and parallel combinations, are used in conjunction with the equations of Poiseuille and Hartmann to demonstrate the dependence of the rate of flow of mercury in the models on channel dimensions when the models are subjected to transverse magnetic fields. Experimental tests conducted on mercury-saturated, glass-bead packs and a natural rock sample show that a magnetic field applied transversely to the direction of flow retards flow rate. The magnitude of the magnetic effect increased with increasing bead size and field intensity. Results of this work suggest that magnetic fields have potential in the study of the internal geometry of flow channels in porous media. Introduction The purpose of this work is to determine qualitatively by theoretical and experimental considerations whether or not a magnetic method has potential in the study of the basic properties of rock. The nature of the solid surface and the geometry of the pore network in petroleum-bearing rock plays an important role in the flow behavior of fluids in a petroleum reservoir. Hence, any technique of study that would provide new and additional information on the rock matrix would contribute to a better understanding of petroleum reservoir performance. One such technique appearing to offer performance. One such technique appearing to offer promise is in the area of magnetohydrodynamics. promise is in the area of magnetohydrodynamics. While much research, both theoretical and experimental, has been devoted to the problems concerned with the flow of conducting fluids in transverse magnetic fields in single channels, very little information has been published regarding the behavior of conducting liquids in porous media under the influence of a transverse magnetic field. Perhaps this dearth of information can be attributed Perhaps this dearth of information can be attributed to two main causes:the pores and pore connections are generally so small that intense magnetic fields are required to produce Hartmann numbers of sufficient magnitude to exert appreciable influence on flow rate, andthe extreme complexity of the channel systems in porous media render them intractable to theoretical analysis unless numerous assumptions are made to simplify network geometry. When a conducting fluid moves in a channel in a transverse magnetic field, a force is exerted on the fluid which retards its flow. The magnitude of flow-rate retardation increases with increasing field intensity, channel dimensions and channel-wall conductivity. These magnetohydrodynamic phenomena and theory have been described and developed by various investigators. Since a petroleum reservoir rock is an interconnected network of pores and channels within a rock framework, one would anticipate that the geometry of the network would exert some influence on the magnitude of the effect of a transverse magnetic field on the rate of flow of a conducting fluid therein. The purpose of this work is to demonstrate through the use of simple models and experimental data that the magnetic field effect on flow rate has potential for use in determining size and size potential for use in determining size and size distribution of pores in porous materials. THEORY Electromagnetic induction in liquids is not completely defined, and the complexities involved in many cases appear to defy true analytical expression. However, by applying some simplifying assumptions, these cases may be made tractable to solution to provide qualitative indication of system behavior. The following analysis was conducted in conjunction with laboratory tests to determine if magnet ohydrodynamics has possible potential as a tool for studying the internal geometry of porous systems. When a conducting liquid moves in a channel in a transverse magnetic field, an emf is developed in the channel normal to both the channel axis and the magnetic field. This emf causes circulating currents to flow in the liquid as shown in Fig. 1. SPEJ P. 223

Slug Formation Analysis of Liquid–Liquid Two-Phase Flow in T-Junction Microchannels

2019 ◽  
Vol 11 (5) ◽  
Author(s):  
Jin-yuan Qian ◽  
Xiao-juan Li ◽  
Zan Wu ◽  
Zhi-jiang Jin ◽  
Junhui Zhang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Rate Ratio ◽  
Two Phase Flow ◽  
Continuous Phase ◽  
Channel Width ◽  
Flow Rate Ratio ◽  
Width Ratio ◽  
Phase Flow ◽  
Channel Depth ◽  
Two Phase

Slug flow is a common flow pattern in the liquid–liquid two-phase flow in microchannels. It is an ideal pattern for mass transfer enhancement. Many factors influence the slug formation such as the channel geometries (channel widths, channel depth), flow rates of the two phase, and physical properties. In this paper, in order to investigate the liquid–liquid two-phase slug formation in a T-junction microchannel quantitatively, the volume of fluid (VOF) method is adopted to simulate the whole slug formation process. With the validated model, the effects of the disperse phase channel width, channel depth, and two-phase flow rate ratio on slug formation frequency and slug size (slug volume and slug length) are analyzed with dimensionless parameters. Dimensionless parameters include the disperse-to-continuous phase channel width ratio, height-to-width ratio, and two-phase flow rate ratio. Results show that both the channel geometry and two-phase flow rate ratio have a significant influence on slug formation. Compared with the conventional slug formation stages, a new stage called the lag stage emerges when the disperse phase channel width decreases to half of the continuous phase channel width. When the channel depth decreases to one third of the continuous phase channel width, the flow patterns become unstable and vary with the two-phase flow rate ratio. Moreover, empirical correlations are proposed to predict the slug formation frequency. The correlation between slug formation frequency and slug volume is quantified.

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