Download or read book Oscillating Dispersed Phase Co Flow Microfluidic Droplet Generation written by Amin Shams Khorrami and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Droplet-based microfluidics have emerged as versatile platforms offering unique advantages in biology and chemistry. Although there is adequate control on size and monodispersity, most conventional microfluidic techniques cannot generate more than one droplet size at a time in a continuous and high-throughput manner. Moreover, the widely used co-flow microfluidic droplet generation technique is bottlenecked with droplet polydispersity at high throughputs due to the transition from a more-stable dripping regime to an instable jetting regime at high d-phase flow rates. We applied nozzle oscillatory motion to generate an axial shear gradient as well as inducing an additional transverse drag force. We hypothesized that the combined effects of axial and transverse drags can be used for overcoming the aforementioned limitations of co-flow systems. Nozzle oscillation effect was studied in both dripping and jetting regimes to generate repeatable patterns of multi-size monodisperse droplets and jet length reduction in different biphasic systems, respectively.
Download or read book Microfluidics written by Sebastian Seiffert and published by Walter de Gruyter GmbH & Co KG. This book was released on 2019-12-02 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfluidics introduces the theory and practice of fluid flow on small scales. The exquisite control of such flow at low Reynolds numbers allows liquids to be processed in either a well-defined co-flow or a well-defined segmented-flow fashion. Both lays a ground for high-throughput analytics and advanced materials design. With that, this book is ideal for research scientists and Ph.D. students in the fields of chemistry, chemical engineering, biotechnology, and materials science.
Download or read book Morphology and Development of Droplet Deformation Under Flow Within Microfluidic Devices written by Molly K. Mulligan and published by . This book was released on 2012 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microfluidics is the science of processing microliters or less of fluid at a time in a channel with dimensions on the order of microns. The small size of the channels allows fluid properties to be studied in a world dominated by viscosity, surface tension, and diffusion rather than gravity and inertia. Microfluidic droplet generation is a well studied and understood phenomena, which has attracted attention due to its potential applications in biology, medicine, chemistry and a wide range of industries. This dissertation adds to the field of microfluidic droplet studies by studying individual droplet deformation and the process of scaling-up microfluidic devices for industrial use. The study of droplet deformation under extensional and mixed shear and extensional flows was performed within a microfluidic device. Droplets were generated using a flow-focusing device and then sent through a hyperbolic contraction downstream of the droplet generator. The hyperbolic contraction allowed the smallest droplets to be deformed by purely extensional flows and for the larger droplets to experience mixed extensional and shear flows. The shear resulted from the proximity of the droplet to the walls of the microfluidic channel. The continuous phase in all of these devices was oil and the dispersed phase was water, an aqueous surfactant solution, or an aqueous suspension of colloidal particles. Droplet deformation dynamics are affected by the use of surfactants and colloidal particles, which are commonly used to stabilize emulsion droplets again coalescence. Microfluidic droplet generating devices have many potential industrial applications, however, due to the low output of product from a single droplet generating device, their potential has not been realized. Using six parallel flow-focusing droplet generators on a single chip, the process of microfluidic droplet formation can be scaled up, thus resulting in a higher output of droplets. The tuning of droplet size and production frequency can be achieved on chip by varying the outlet tubing lengths, thus allowing for a single device to be used to generate a range of droplet sizes.
Download or read book Micro Nanofluidics and Lab on Chip Based Emerging Technologies for Biomedical and Translational Research Applications Part B written by and published by Academic Press. This book was released on 2022-01-28 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: Micro/Nanofluidics and Lab-on-Chip Based Emerging Technologies for Biomedical and Translational Research Applications - Part B, Volume 187 represents the collation of chapters written by eminent scientists worldwide. Chapters in this new release include Design and fabrication of microfluidics devices for molecular biology applications, Micro/Nanofluidics devices for drug delivery, From organ-on-chip to body-on-chip: the next generation of microfluidics platforms for in vitro drug toxicity testing, Micro/Nanofluidics for high throughput drug screening, Design, fabrication and assembly of lab-on-a-chip and its uses, Advances in microfluidic 3D cell culture for pre-clinical drug development, Tissue and organ culture on lab-on-a chip for biomedical applications, and much more. Offers a basic understanding of the state-of-the-art design and fabrication of microfluidics/ nanofluidics and lab on chip Explains how to develop microfluidics/nanofluidic for advanced application such as healthcare, high throughout drug screening, 3D cell culture and organ-on-chip Discusses the emerging demands and research of micro/nanofluidic based devices in biomedical and translational research applications
Download or read book Droplet Microfluidics written by Eric Brouzes and published by MDPI. This book was released on 2021-05-06 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Microdroplet Technology written by Philip Day and published by Springer Science & Business Media. This book was released on 2012-07-28 with total page 249 pages. Available in PDF, EPUB and Kindle. Book excerpt: Microdroplet technology has recently emerged to provide new and diverse applications via microfluidic functionality, especially in various areas of biology and chemistry. This book, then, gives an overview of the principle components and wide-ranging applications for state-of-the-art of droplet-based microfluidics. Chapter authors are internationally-leading researchers from chemistry, biology, physics and engineering that present various key aspects of micrdroplet technology -- fundamental flow physics, methodology and components for flow control, applications in biology and chemistry, and a discussion of future perspectives. This book acts as a reference for academics, post-graduate students, and researcher wishing to deepen their understand of microfluidics and introduce optimal design and operation of new droplet-based microfluidic devices for more comprehensive analyte assessments.
Download or read book Droplet based Microfluidic Chip Design for High Throughput Screening Applications written by Xiaoming Chen and published by . This book was released on 2015 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt: Droplet-based microfluidics has been considered as a prospective tool for high throughput screening analysis, which is highly demanded in a wide range of areas including but not limited to life science research, drug discovery, material synthesis and environmental monitoring. Low sample consumption, reduced reaction time, high throughput manipulation, fast mixing, and prevention of cross contamination at channel walls are just some of the benefits of droplet-based microfluidics. Although extensive research efforts have been reported in the study of droplet-based microfluidics over the past decades, it has yet to be widely commercialized. One of the challenges that limit droplet microfluidic chips from being commercialized is the difficulty in integrating multiple functions robustly without increasing the device footprint. Major functionalities of interest include generating droplets with controlled volume and frequency, and precisely controlling and manipulating each individual droplet such as sorting, detecting, merging, splitting, pairing, mixing, trapping, releasing, long term and short term storing, etc. Since many of these functionalities rely on the accuracy of droplet generation which is the first step, it is crucial to investigate the droplet formation process and understand how to design microfluidic structures to manipulate each individual droplet effectively. To this end, this thesis started with a fundamental study of droplet generation in a flow focusing geometry based on extensive experimental data, from which a physical model was developed to describe droplet formation processes, then move on to study droplet generation in a geometry with two junctions in series, with the goal of improving single encapsulation (one particle per droplet) efficiency. Later, droplet merging towards whole genome amplification and drug screening applications was investigated, and finally a microfluidic chip integrated with multiple functionalities was developed, and its robustness was validated. The first project studied the fundamental principles of liquid-liquid droplet generation in a flow focusing device. This work presents a 3D physical model with less fitting parameters than existing ones. The model describes droplet formation process in flow focusing devices operating in the squeezing regime, where droplet size is usually larger than the channel width, and was developed based on a systematic and extensive experimental study. In particular, it incorporates an accurate geometric description of the 3D droplet shape during the formation process, an estimation of the time period for the formation cycle based on the conservation of mass, and a semi-analytical model predicting the pressure drop over the 3D corner gutter between the droplet curvature and channel walls, which allows droplet size, spacing and formation frequency to be determined accurately. The model takes into account change in channel geometry (height to width ratio), viscosity contrast, flow rate ratio and capillary number with a wide variety. In the second project, liquid-liquid droplet generation in a flow focusing device with two junctions in series was investigated using experimental approach. Extra emphasis was placed on the device's ability to encapsulate single cell and particle. . This study employs glycerol solutions with different concentrations as the dispersed phase, which tends to form stratified flow at the first junction due to viscosity contrast. The stratified flow proceeds to form droplets in oil stream at the second junction. To obtain a comprehensive understanding of the droplet formation dynamics involving stratified flow, five different scenarios were considered. These include a single stream of 10%glycerol aqueous solution, a single stream of 80%glycerol aqueous solution, as well as the simultaneous flow of multiple streams of the above mentioned solution. Droplet size and formation period for these cases were compared and analyzed considering the same geometric and flow conditions. It is found that stratified flow structure strongly influences droplet formation dynamics such as droplet size and formation frequency and the scenario with 80%glyc surrounded by 10%glyc in the first junction generates the largest droplet size. Each structure finds its own applications. For the purpose of single encapsulation, the scenario with 80%glyc surrounded by 10%glyc in the first junction is most suitable because the high viscosity of 80%glyc allows particles to be focused into a thin stream and spaced out before entering droplets. On the other hand, the scenario with two fluids side by side in the first junction generates droplets with high monodispersity for a larger range of flow ratios, which is useful for high throughput reactions involving different reagents. After understanding the fundamentals of the droplet generation process, several designs for practical use were proposed to generate or manipulate droplets. These designs include: i) a flow focusing device that improve droplet size uniformity through changing junction angle; ii) a system for droplet generation on demand, which is essential to controlling droplets of specific reagents; iii) a geometry for generating droplet pairs with uniform droplet sizes and controlled droplet spacing , and to study the interaction between two nearby droplets; iv) a simple droplet merging chamber for controlled reagent volume; and v) a droplet trapping and releasing on demand system for drug screening. The final part of this thesis presents a complex microfluidic system that integrates multiple functionalities, including droplet generation, pairing, trapping, merging, mixing, and releasing. The criterion of this design was analyzed and verified by experiments. This design does not require any synchronization of droplet frequency, spacing or velocity, which makes the microfluidic chip work robustly, and is controlled entirely by liquid flow eliminating the needs for electrodes, magnets or any other moving parts. This design can be applied to many chemical or biological reactions, such as drug screening, chemical synthesis, and cell culture, etc.
Download or read book Designing Droplet Microfluidic Networks written by Andreas Grimmer and published by Springer. This book was released on 2019-07-04 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book describes automatic methods for the design of droplet microfluidic networks. The authors discuss simulation and design methods which support the design process of droplet microfluidics in general, as well as design methods for a dedicated droplet routing mechanism, namely passive droplet routing. The methods discussed allow for simulating a microfluidic design on a high-abstraction level, which facilitates early validation of whether a design works as intended, automatically dimensioning a microfluidic design, so that constraints like flow conditions are satisfied, and automatically generating meander designs for the respective needs and fabrication settings. Dedicated methods for passive droplet routing are discussed and allow for designing application-specific architectures for a given set of experiments, as well as generating droplet sequences realizing the respective experiments. Together, these methods provide a comprehensive “toolbox" for designers working on droplet microfluidic networks in general and an integrated design flow for the passive droplet routing mechanism in particular. Provides both a comprehensive “toolbox" for designers working on droplet microfluidic networks in general and an integrated design flow for the passive droplet routing mechanism in particular; Describes for the first time CAD methods for droplet microfluidic networks, along with the first integrated design process; Includes open source implementations, in order to reach the largest possible user group within the domain of microfluidics.
Download or read book Drop Generation Using Cross flow in Rigid Body Rotation written by Haipeng Zhang and published by . This book was released on 2018 with total page 124 pages. Available in PDF, EPUB and Kindle. Book excerpt: Inspired by crossflow membrane droplet generation and microfluidic droplet generation, I propose an easy method to generate monodisperse drops using cross-flow caused by rigid body rotation. In this approach, a dispersed phase (DP) liquid was injected through a stationary vertical needle into an immiscible continuous phase (CP) liquid which was in rigid body rotation. A DP drop growing at the end of the needle experienced fluid dynamic forces from the horizontal CP flow, and it was detached from the needle when it had grown to a certain size. This study investigated the relationship between the resultant size of drops and the controllable experimental factors including the flow velocity of the CP at the needle end and the flow rate of the DP through the needle.
Download or read book Droplet Microfluidics written by Carolyn Ren and published by Royal Society of Chemistry. This book was released on 2020-11-20 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Droplet microfluidics offers tremendous potential as an enabling technology for high-throughput screening. It promises to yield novel techniques for personalised medicine, drug discovery, disease diagnosis, establishing chemical libraries, and the discovery of new materials. Despite the enormous potential to contribute to a broad range of applications, the expected adoption has not yet been seen, partly due to the interdisciplinary nature and the fact that, up until now, information has been scattered across the literature. This book goes a long way to addressing these issues. Edited by two leaders, this book has drawn together expertise from around the globe to form a unified, cohesive resource for the droplet microfluidics community. Starting with the basic theory of droplet microfluidics before introducing its use as a tool, the reader will be treated to chapters on important techniques, including robust passive and active droplet manipulations and applications such as single cell analysis, which is key for drug discovery. This book is a go-to resource for the community yearning to adopt and promote droplet microfluidics into different applications and will interest researchers and practitioners working across chemistry, biology, physics, materials science, micro- and nano-technology, and engineering.
Download or read book Control of Emulsion Drop Production in Flow Focusing Microfluidics written by Haejune Kim and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Generating droplets using flow-focusing microfluidics in multiphase flows has reached its limit that it cannot generate submicrometer droplets in size. Flow focusing geometry together with an electric field has been used to make smaller droplets in microchannels. The droplet size was controllable by the flow rate ratio as well as the electric field. The droplets size decreased as the voltage increased. A Taylor cone was formed to generate very fine droplets which were less than 1mB in diameter. The tip made smaller droplets due to the tangential force by the electric field. A small inner flow rate and high electric field were required to form a stable Taylor cone in a DC electric field. The droplet size, however, was not stable at a small water flow rate because the flow rate was not as accuate as required. When I used a modified syringe pump with more accurate flow rate control, I was able to obtain a stable set of data. A small change in droplet size occurred at low voltage. The drop size changed dramatically, when the voltage was high enough. I also observed how an AC electric field affects the droplet size. The droplet size was not solely determined by the voltage. This is because of the imbalance of the supplied flow rate and the emitted flow rate. I also found that the droplet size is related to the tip position of the dispersed phase. The droplet size decreased as the tip stretched more. Typically, the microfluidic device generated monodispese droplets in narrow size distribution. It also generated a bigger droplet followed by a smaller one consecutively at low flow rate ratio of inner and outer fluid flow. To understand this instability of drop formation, a numerical calculation was conducted. The simulation results showed inside of the tip still pointed downstream after it generated a big droplet. Then, the tip generated another smaller droplet while the tip was stretched. Finally, the tip moved back and began a new cycle.
Download or read book Generation and Applications of Bubbles and Droplets in Microfluidic Systems written by Michinao Hashimoto and published by . This book was released on 2009 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chapter 5 described formation of composite structure of stable lattices of bubbles and droplets by simultaneous use of multiple flow-focusing generators. Chapter 6, 7 and 8 discussed the development of emulsion-based applications in optofluidics, material synthesis, and chemical communications: Chapter 6 discussed the development of the diffraction gratings using self-assembled lattice structures of bubbles. Changes in flow parameters demonstrated dynamic switching of the periodicity of the gratings. Chapter 7 discussed generation of monodisperse, drug-loaded poly (lactic-co-glycolic acid) (PLGA) particles using microfluidic flow-focusing generators. The size-dependent kinetics of drug release was demonstrated. In addition, kinetics of drug release from particles fabricated using a microfluidic method and a conventional method were compared. Chapter 8 describes a new method to generate a series of optical pulses by aligning an optical mask below a microfluidic channel in which transparent droplets flows through an opaque continuous phase. This study is intended to explore a new field in chemical communications --that is, generation, transmission and detection of information using chemistry and chemical properties of matter.
Download or read book Fundamentals and Applications of Microfluidics Third Edition written by Nam-Trung Nguyen and published by Artech House. This book was released on 2019-01-31 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: Now in its Third Edition, the Artech House bestseller, Fundamentals and Applications of Microfluidics, provides engineers and students with the most complete and current coverage of this cutting-edge field. This revised and expanded edition provides updated discussions throughout and features critical new material on microfluidic power sources, sensors, cell separation, organ-on-chip and drug delivery systems, 3D culture devices, droplet-based chemical synthesis, paper-based microfluidics for point-of-care, ion concentration polarization, micro-optofluidics and micro-magnetofluidics. The book shows how to take advantage of the performance benefits of microfluidics and serves as an instant reference for state-of-the-art microfluidics technology and applications. Readers find discussions on a wide range of applications, including fluid control devices, gas and fluid measurement devices, medical testing equipment, and implantable drug pumps. Professionals get practical guidance in choosing the best fabrication and enabling technology for a specific microfluidic application, and learn how to design a microfluidic device. Moreover, engineers get simple calculations, ready-to-use data tables, and rules of thumb that help them make design decisions and determine device characteristics quickly.
Download or read book Predicting Droplet Formation on Centrifugal Microfluidic Platforms written by Jacob Alfred Moebius and published by . This book was released on 2015 with total page 57 pages. Available in PDF, EPUB and Kindle. Book excerpt: Centrifugal microfluidics is a widely known research tool for biological sample and water quality analysis. Currently, the standard equipment used for such diagnostic applications include slow, bulky machines controlled by multiple operators. These machines can be condensed into a smaller, faster benchtop sample-to-answer system. Sample processing is an important step taken to extract, isolate, and convert biological factors, such as nucleic acids or proteins, from a raw sample to an analyzable solution. Volume definition is one such step. The focus of this thesis is the development of a model predicting monodispersed droplet formation and the application of droplets as a technique for volume definition. First, a background of droplet microfluidic platforms is presented, along with current biological analysis technologies and the advantages of integrating such technologies onto microfluidic platforms. Second, background and theories of centrifugal microfluidics is given, followed by theories relevant to droplet emulsions. Third, fabrication techniques for centrifugal microfluidic designs are discussed. Finally, the development of a model for predicting droplet formation on the centrifugal microfluidic platform are presented for the rest of the thesis. Predicting droplet formation analytically based on the volumetric flow rates of the continuous and dispersed phases, the ratios of these two flow rates, and the interfacial tension between the continuous and dispersed phases presented many challenges, which will be discussed in this work. Experimental validation was completed using continuous phase solutions of different interfacial tensions. To conclude, prospective applications are discussed with expected challenges.
Download or read book Microscale Fluids Engineering for Droplet Microfluidics and Drag Reduction written by Pooyan Tirandazi and published by . This book was released on 2020 with total page 151 pages. Available in PDF, EPUB and Kindle. Book excerpt: "Understanding the dynamics of fluids has enabled humans to devise strategies for a myriad of global challenges on a wide range of scales, from nanotechnology to space exploration. By designing and developing systems for manipulating fluid flows, researchers not only constantly optimize many of the conventional approaches to older engineering tasks, but also establish novel methods to tackle new and unsolved problems in science and technology. The advent of microfabrication and microfluidics along with improvements in numerical methodologies and computational power have equipped researchers with unprecedented resources to address these problems. In this work, I aim to investigate two areas where fluids engineering plays a critical role: droplet generation in microfluidic systems and fluid drag reduction of microtextured surfaces. In the first part, I study a relatively new area - droplet generation in microchannels using a high-speed gas phase flow. The use of microdroplets has become ubiquitous in many Lab-on-a-Chip applications ranging from material synthesis to biochemical sensing and testing. Droplet-microfluidics offers a promising approach for controlled generation and manipulation of uniform fluid entities. Despite the versatility and unparalleled control of the droplet formation and transport, the range of droplet microfluidic applications could be greatly expanded by enhancing the per-channel throughput and improving the interaction of droplets and jets with the continuous flow and the microchannel. I investigate a new class of droplet-based systems that uses a high-speed gaseous flow to generate uniform liquid droplets in a flow-focusing geometry. The interaction of the liquid and gas inside the microchannel creates distinct flow patterns. By characterizing the operation extent of resulting flow maps, I then focus on the Dripping and Jetting modes of droplet formation. To improve the performance of the droplet generation, I design and fabricate a three-dimensional microchannel architecture to facilitate formation of a contact-less liquid jet within the air flow inside the microchannel. Droplet generation frequency in this non-planar microchannel increase by at least one order of magnitude in comparison to conventional liquid-liquid droplet systems. The high-speed nature of the flows in this system, however, poses new challenges, namely inertial and compressibility effects on precise control of the jets and droplets. I use numerical simulations to further investigate the flow dynamics and determine the local pressure and velocity of the air inside the microchannel. The knowledge gained from this discussion of the fundamentals and physics is subsequently leveraged in applications that can benefit from this system. I propose a novel technique to use droplets as isolated micro-reactors for absorbing and detecting airborne targets and provide a proof-of-concept for sensing gaseous ammonia using sample digitization with microdroplets. In addition, I present the potential of using gas-liquid droplets as a template for polymer particle fabrication by showing experimental results that demonstrate the generation of calcium alginate microgels purely in air. At the end of this part, I discuss the current challenges in each application and suggest possible solutions towards effective implementation of this system for next generation microfluidic systems in particle synthesis and biochemical diagnostics. In the second part, I revisit a relatively old problem - understanding the dynamics of the laminar flow over textured surfaces for drag reduction applications. Inspired by the natural skins of certain plants and animals, introducing surface corrugations is a proven strategy to reduce the fluid drag and create a superhydrophobic effect, which has potential environmental and economic benefits. I examine the effects of periodic transverse grooves on the laminar boundary layer flow for mid- to high-Reynolds numbers (1000-25000). The width-to-depth aspect ratio of the grooves (AR) is a critical parameter that determines flow behavior near the grooves. Using finite element simulations, I study the local and temporal pressure and velocity fields in rectangular grooves for a wide range of aspect ratios (0.2
Download or read book Droplet and Digital Microfluidics written by Sanket Goel and published by Elsevier. This book was released on 2024-03-11 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Droplet and Digital Microfluidics: Ideation to Implementation is a detailed introduction to the dynamics of droplet and digital microfluidics, also featuring coverage of new methods and applications. The explosion of applications of microelectromechanical systems (MEMS) in recent years has driven demand for expertise and innovation in fluid flow in the microchannels they contain. In this book, detailed descriptions of methods for biological and chemical applications of microfluidics are provided, along with supporting foundational knowledge. In addition, the principles of droplet and digital microfluidics are explained, along with their different applications and governing physics. New additions to the technological knowledgebase that enable advances in droplet and digital microfluidics include machine learning and exciting future avenues for research. Provides step-by-step fabrication, testing, and characterization instructions in each chapter to support implementation Includes explanations of applications and methods in biological and chemical settings Describes the path to automation of digital and droplet microfluidic platforms
Download or read book DEVELOPMENT OF DROPLET BASED MICROFLUIDIC DEVICES FOR MICRODROPLET TRAPPING AND PAIRING written by Preethi Gopalan and published by . This book was released on 2010 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: The droplet based microfluidic technology has become indispensable in many chemical, biomedical research and high-throughput assay applications. The ability to controllably merge droplets within flow systems is of high importance when performing complex chemical or biological analysis. However, in order to perform controlled fusion reaction one needs to perform controlled droplet trapping and pairing. Recent microfluidic systems are capable of pairing the droplets by using unstabilized flow pattern. Controlled droplet pairing and fusion, especially for same-sized droplet pairing, is still a challenge, mostly because of the difficulty to manipulate droplets. It is also seen that it requires to control the droplet generation along with the flow rate control simultaneously which is also difficult to realize.^In our research, a serial flowing microfluidic system and an obstruction based microfluidic system are presented for checking the droplet flow pattern along the system using hydrodynamic resistance phenomenon. In addition to this, we also checked the device working for droplet generation along with sequential trapping and pairing of aqueous micro-droplets of different liquids. It is more robust as compared to the prior research done in this area. These systems are competent of accomplishing multiple functions including droplet generation, transportation, trapping and merging on a single integrated device. These devices consist of three different functional regions: flow focusing droplet generator; a single droplet trap region and pairing region. Our designs were based on the principle of exploiting hydrodynamic resistance of the columnar structure in the microfluidic channel. The device designs include two inlets for oil and water.^Similar structure was embedded at the outlet for the generation of second droplet of different liquid. In a typical scenario, droplets would be generated at the T-junction and would travel through the microfluidic channel to enter the single droplet trapping area. During the reverse flow, the trapped droplets in the first phase would be released and would enter the pairing chamber. These droplets would be held until another droplet of different liquid to combine with it. Second droplet would travel in the reverse flow direction and would be trapped in the pairing chamber along with the first droplet to combine with it. Deionized water and gel were used as the aqueous phase and mineral oil as the oil phase. 2% (w/w) Span-80 was used as surfactant. These devices were also simulated using PSpice and COMSOL Multiphysics to verify the droplet trapping and pairing sequences before fabrication.^Finally, we designed and tested the double droplet trapping system in a serial flowing microfluidic device along with the obstruction based microfluidic device. The efficiency for single droplet trapping in forward flow was about 99%, single droplet trapping in reverse flow direction was about 90-95% for both serial and obstruction based microfluidic device. For droplet pairing, the serial microfluidic device had an efficiency of 40-45% where as the obstruction based microfluidic had 60-65% efficiency. These devices were very simple and could very efficiently trap two different liquid droplets in a chamber without merging and with the help of an external electric field they could be selectively merged.
