Studying Droplet Behavior and Capillary Flow in Open Microfluidic Channels PDF Download

Author: Jing Jei Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
This dissertation discusses advancements in open channel microfluidics, the design and fabrication of open channels and capillary pumps, and methods to manipulate open channels. An open droplet-based microfluidics platform is demonstrated with promising future applications. Additionally, an expression to measure the velocity of capillary flow in an open channel and design guidelines for an efficient capillary pump are presented.Chapter 1 discusses the field of microfluidics and the advantages of such platforms. The fundamentals of open microfluidics is presented along with the benefits of open channel systems. Capillary flow is discussed, and the necessary considerations for fabrication of channels to ensure that the fluid in the system is driven by capillary means is provided. Droplet-based microfluidics is a large subfield of microfluidics, which is briefly reviewed, and a need for further fundamental and applied work using droplet-based systems which are completely driven by capillary flow is discussed. Finally, capillary pumps provide a solution to the inherent decrease of velocity (and flow rate) observed in channels driven by capillary flow. Chapter 2 introduces droplet-based microfluidics where droplets are formed in an open channel that is completely driven by capillary means. Our work represents the first time that this phenomenon was observed and studied. The interaction that exists between a droplet and the surrounding phase is described in detail. Chapter 3 explores fundamental microfluidic features in open channels: droplet splitting, multiple droplets, and droplet merging. An example of an open platform that enables users to manipulate droplets on the same chip is presented. Chapter 4 investigates capillary flow in an open channel, and an expression to measure velocity derived from the Lucas-Washburn-Rideal law is presented. The capillary flow in bifurcations and networks of open channels are studied. Chapter 5 investigates the theory of open capillary pumps to alleviate the inherent decrease of velocity and flow rate during capillary flow. Design guidelines of an efficient open capillary pump are discussed. Chapter 6 concludes the thesis with an overall perspective of the field and other experimental proposals to improve the overall design of open channels and capillary pumps and to enable applications with the platform.

Author: Jean Berthier
Publisher: Morgan & Claypool Publishers
ISBN: 1643276646
Category : Technology & Engineering
Languages : en
Pages : 171

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Book Description
Open microfluidics, the study of microflows having a boundary with surrounding air, encompasses different aspects such as paper or thread-based microfluidics, droplet microfluidics and open-channel microfluidics. Open-channel microflow is a flow at the micro-scale, guided by solid structures, and having at least a free boundary (with air or vapor) other than the advancing meniscus. This book is devoted to the study of open-channel microfluidics which (contrary to paper or thread or droplet microfluidics) is still very sparsely documented, but bears many new applications in biology, biotechnology, medicine, material and space sciences. Capillarity being the principal force triggering an open microflow, the principles of capillarity are first recalled. The onset of open-channel microflow is next analyzed and the fundamental notion of generalized Cassie angle (the apparent contact angle which accounts for the presence of air) is presented. The theory of the dynamics of open-channel microflows is then developed, using the notion of averaged friction length which accounts for the presence of air along the boundaries of the flow domain. Different channel morphologies are studied and geometrical features such as valves and capillary pumps are examined. An introduction to two-phase open-channel microflows is also presented showing that immiscible plugs can be transported by an open-channel flow. Finally, a selection of interesting applications in the domains of space, materials, medicine and biology is presented, showing the potentialities of open-channel microfluidics.

Author: Jean Berthier
Publisher: John Wiley & Sons
ISBN: 1118720822
Category : Science
Languages : en
Pages : 384

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Book Description
Open microfluidics or open-surface is becoming fundamental in scientific domains such as biotechnology, biology and space. First, such systems and devices based on open microfluidics make use of capillary forces to move fluids, without any need for external energy. Second, the "openness" of the flow facilitates the accessibility to the liquid in biotechnology and biology, and reduces the weight in space applications. This book has been conceived to give the reader the fundamental basis of open microfluidics. It covers successively The theory of spontaneous capillary flow, with the general conditions for spontaneous capillary flow, and the dynamic aspects of such flows. The formation of capillary filaments which are associated to small contact angles and sharp grooves. The study of capillary flow in open rectangular, pseudo-rectangular and trapezoidal open microchannels. The dynamics of open capillary flows in grooves with a focus on capillary resistors. The case of very viscous liquids is analyzed. An analysis of suspended capillary flows: such flows move in suspended channels devoid of top cover and bottom plate. Their accessibility is reinforced, and such systems are becoming fundamental in biology. An analysis of “rails” microfluidics, which are flows that move in channels devoid of side walls. This geometry has the advantage to be compatible with capillary networks, which are now of great interest in biotechnology, for molecular detection for example. Paper-based microfluidics where liquids wick flat paper matrix. Applications concern bioassays such as point of care devices (POC). Thread-based microfluidics is a new domain of investigation. It is seeing presently many new developments in the domain of separation and filtration, and opens the way to smart bandages and tissue engineering. The book is intended to cover the theoretical aspects of open microfluidics, experimental approaches, and examples of application.

Author: Jean Berthier
Publisher: John Wiley & Sons
ISBN: 1118720865
Category : Science
Languages : en
Pages : 331

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Book Description
Open microfluidics or open-surface is becoming fundamental in scientific domains such as biotechnology, biology and space. First, such systems and devices based on open microfluidics make use of capillary forces to move fluids, without any need for external energy. Second, the "openness" of the flow facilitates the accessibility to the liquid in biotechnology and biology, and reduces the weight in space applications. This book has been conceived to give the reader the fundamental basis of open microfluidics. It covers successively The theory of spontaneous capillary flow, with the general conditions for spontaneous capillary flow, and the dynamic aspects of such flows. The formation of capillary filaments which are associated to small contact angles and sharp grooves. The study of capillary flow in open rectangular, pseudo-rectangular and trapezoidal open microchannels. The dynamics of open capillary flows in grooves with a focus on capillary resistors. The case of very viscous liquids is analyzed. An analysis of suspended capillary flows: such flows move in suspended channels devoid of top cover and bottom plate. Their accessibility is reinforced, and such systems are becoming fundamental in biology. An analysis of “rails” microfluidics, which are flows that move in channels devoid of side walls. This geometry has the advantage to be compatible with capillary networks, which are now of great interest in biotechnology, for molecular detection for example. Paper-based microfluidics where liquids wick flat paper matrix. Applications concern bioassays such as point of care devices (POC). Thread-based microfluidics is a new domain of investigation. It is seeing presently many new developments in the domain of separation and filtration, and opens the way to smart bandages and tissue engineering. The book is intended to cover the theoretical aspects of open microfluidics, experimental approaches, and examples of application.

Author: Pinar England
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
This work is a study to understand the various aspects of a microfluidic device. In the first half we take the role of an end user, experimenting to learn how best to use the device efficiently. In the second half we are the manufacturer, trying to fabricate a user friendly, and fully functioning microfluidic device. As the end user, we have three different T-junction droplet generator devices, with similar geometries. We start investigating by generating water droplets in an oil medium. They self-organise into various flow patterns: single-profile, double-helix profile and triple-helix profile. We document how, with increasing flow rate ratio and capillary number, we observe more densely packed droplet flow patterns. The device with the deeper expansion channel provides more space for the droplets and they self-organise the triple-helix pattern in 3-dimension. We then use the same devices to generate droplets for which we can calculate the volume. The fluid flow in a microchannel happens in four different regimes: ballooning, squeezing, dripping and jetting regimes. In single-cell and single-molecule analysis devices, the ability to create droplets on demand and of a certain volume is a desired capability. This can be achieved by understanding and learning how to use the fluid flow characteristics accurately. We experiment with the three different sized microfluidic devices, to measure the droplet volume throughout the squeezing to dripping regimes. This is achieved by manipulating the capillary number and the flow rate ratio. We observe a similar result as with the flow patterns: that the capillary number has an impact on the droplet volume. As the capillary number increases the droplet diameter decreases. Further, for a set capillary number we can fine tune the droplet diameter by changing the flow rate ratio. As the flow rate ratio increases the volume of water droplets increases, despite the fact the capillary number is set. These coincide with our flow pattern results. Our results fit to the scaling law to predict the droplet size introduced by Tanet al. in 2008 [51]. Unlike some other authors in the literature, we did not observe a critical capillary number where the droplet volume changes suddenly. However, we did observe a transition area where we cannot define the regime of the fluid flow. As the manufacturer we designed and fabricated our own planar free standing microfluidic devices using a polymer called SU-8. After looking into the weaknesses and the strengths of using SU-8, we describe how we successfully fabricated working devices and developeda new procedure in adhesive low temperature bonding. We finish by considering the challenges of connecting micro sized structures to a macro sized syringe pump, and fabricated a chip-holder inspired by applications in industry.

Author: Ulri Nicole Lee
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
This dissertation discusses the applications for open microfluidics in emerging technologies for studying human health and the environment. Open microfluidics is a sub-field of microfluidics that is quickly gaining traction for technologies across biology and the environment. The open nature of the microchannels enables flexibility to the user for adding or removing components and makes it simple to use. Chapter 1 introduces how microfluidics has traditionally been used and provides a background of open microfluidics and the common methods used to fabricate devices. Chapter 2 evaluates rapid injection molding, a more economical version of traditional injection molding, for open microfluidic cell-based technologies. Minimum dimensions and dimension accuracy are investigated for applications with fluorescence imaging. Chapter 3 highlights a novel method for generating droplets in an open microfluidic device that utilizes natural hydrostatic pressure and therefore does not require pumps or external equipment to generate the droplets. Additionally, potential use cases are presented for applications in droplet manipulation, patterning, splitting, and fusion. Chapter 4 presents a layer-by-layer hydrogel patterning method made possible by spontaneous capillary flow. An open microfluidic rail-based device is used to pattern entire layers of hydrogels for biological applications in tissue engineering, organoid development, and 3D cell culture. Chapter 5 presents a novel method for capturing airborne particles using microdroplets and open microfluidic channels for shuttling the collected sample across the device. The work presented here demonstrates fundamental open microfluidic principles for droplet generation and fabrication as well as how open microfluidics can be applied to diverse fields of study such as hydrogel patterning and environmental sampling.

Author: Eric Brouzes
Publisher: MDPI
ISBN: 3036501843
Category : Science
Languages : en
Pages : 114

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Book Description
Droplet microfluidics has dramatically developed in the past decade and has been established as a microfluidic technology that can translate into commercial products. Its rapid development and adoption have relied not only on an efficient stabilizing system (oil and surfactant), but also on a library of modules that can manipulate droplets at a high-throughput. Droplet microfluidics is a vibrant field that keeps evolving, with advances that span technology development and applications. Recent examples include innovative methods to generate droplets, to perform single-cell encapsulation, magnetic extraction, or sorting at an even higher throughput. The trend consists of improving parameters such as robustness, throughput, or ease of use. These developments rely on a firm understanding of the physics and chemistry involved in hydrodynamic flow at a small scale. Finally, droplet microfluidics has played a pivotal role in biological applications, such as single-cell genomics or high-throughput microbial screening, and chemical applications. This Special Issue will showcase all aspects of the exciting field of droplet microfluidics, including, but not limited to, technology development, applications, and open-source systems.

Author: Jean Berthier
Publisher:
ISBN:
Category : Mathematics
Languages : en
Pages : 392

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Book Description
The Physics of Microdroplets gives the reader the theoretical and numerical tools to understand, explain, calculate, and predict the often nonintuitive observed behavior of droplets in microsystems. Microdrops and interfaces are now a common feature in most fluidic microsystems, from biology, to biotechnology, materials science, 3D-microelectronics, optofluidics, and mechatronics. On the other hand, the behavior of droplets and interfaces in today's microsystems is complicated and involves complex 3D geometrical considerations. From a numerical standpoint, the treatment of interfaces separating different immiscible phases is difficult. After a chapter dedicated to the general theory of wetting, this practical book successively details: The theory of 3D liquid interfaces The formulas for volume and surface of sessile and pancake droplets The behavior of sessile droplets The behavior of droplets between tapered plates and in wedges The behavior of droplets in microchannels The effect of capillarity with the analysis of capillary rise The onset of spontaneous capillary flow in open microfluidic systems The interaction between droplets, like engulfment The theory and application of electrowetting The state of the art for the approach of 3D-microelectronics using capillary alignment.

Author: Negar Nazari
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Book Description
World energy demand increases as global population increases. Seeking new solutions and improving the current energy systems are two attractive options to address the existing problems. Processes of interest include CO$_{2}$ storage security, hydrogen storage, and enhanced oil recovery. Studying fluid behavior at pore scale, improves understanding of fundamental mechanisms and enables mechanistic control of the processes involved. Multiphase and multi-component fluid flow is dictated and controlled by pore-scale phenomena. Understanding fluid-fluid interactions and multiphase flow behavior in complex porous media is the essential component of optimizing the subsurface energy design. Microfluidic devices with representative geometry, and length scales are essential to delineate the fundamental mechanisms dictating the pore-scale fluid behavior of multiphase flow in fractures and channels. Therefore, a primary objective of this research is to develop cutting-edge microfluidic devices. My research improves mechanical and physical characteristics of transport processes in micromodels through development of new microfluidic devices, thorough experimental frameworks, and computer-assisted techniques to process and model the results. First, we designed and fabricated a new microfluidic device to better enable study of foam microstructure and rheology in planar fractures. The workflow included finite element analysis of several designs to enhance the pressure tolerance of the device. The new design illustrated improved ability to sustain large differential pressure compared to previous designs in the literature. Our findings validated the previous microvisual studies mentioned in the literature and revealed that foam apparent viscosity is a strong function of foam quality and water velocity at small qualities and this dependency decreases for greater foam qualities and water velocities. Second, we investigated foam flow behavior in microscale fractures and developed a mechanistic transient foam flow model using the population balance method. Microscale experiments in fractures with apertures of 25 and 88 $\mu m$ were used to validate the model for pressure drop, gas saturation, and bubble texture. Key differences related to modeling foam in fractures are the potential for continuously varying gas-liquid curvature in fractures and the relationship of this curvature to apparent foam viscosity. Incorporation of a local foam flow resistance factor is important to representing flow physics accurately. Third, we designed and fabricated a new microfluidic device with a meter-long channel and a rectangular cross section to study the flow behavior of long gas bubbles in noncircular-cross-section capillaries. Our calculations of channel curvature, Dean number, and centripetal acceleration for this novel symmetric loop design illustrated that this capillary tube on a chip behaves, essentially, as a straight channel for a wide range of velocity, U. We found that the pressure drop experienced by bubbles varies as $Ca^{2/3}$ over the range $10^{-7}

Author: Daniel D. Joseph
Publisher: Springer Science & Business Media
ISBN: 1461570611
Category : Mathematics
Languages : en
Pages : 478

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Book Description
Two-fluid dynamics is a challenging subject rich in physics and prac tical applications. Many of the most interesting problems are tied to the loss of stability which is realized in preferential positioning and shaping of the interface, so that interfacial stability is a major player in this drama. Typically, solutions of equations governing the dynamics of two fluids are not uniquely determined by the boundary data and different configurations of flow are compatible with the same data. This is one reason why stability studies are important; we need to know which of the possible solutions are stable to predict what might be observed. When we started our studies in the early 1980's, it was not at all evident that stability theory could actu ally work in the hostile environment of pervasive nonuniqueness. We were pleasantly surprised, even astounded, by the extent to which it does work. There are many simple solutions, called basic flows, which are never stable, but we may always compute growth rates and determine the wavelength and frequency of the unstable mode which grows the fastest. This proce dure appears to work well even in deeply nonlinear regimes where linear theory is not strictly valid, just as Lord Rayleigh showed long ago in his calculation of the size of drops resulting from capillary-induced pinch-off of an inviscid jet.