scholarly journals Microfluidic Device for Droplet Pairing by Combining Droplet Railing and Floating Trap Arrays

Micromachines ◽  
2021 ◽  
Vol 12 (9) ◽  
pp. 1076
Author(s):  
Margaux Duchamp ◽  
Marion Arnaud ◽  
Sara Bobisse ◽  
George Coukos ◽  
Alexandre Harari ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Droplet Size ◽  
Microfluidic Device ◽  
Microfluidic Chip ◽  
High Efficiency ◽  
Droplet Microfluidics ◽  
Trapping Efficiency ◽  
Unique Combination ◽  
Chip Design ◽  
Single Droplets

Droplet microfluidics are characterized by the generation and manipulation of discrete volumes of solutions, generated with the use of immiscible phases. Those droplets can then be controlled, transported, analyzed or their content modified. In this wide droplet microfluidic toolbox, no means are available to generate, in a controlled manner, droplets co-encapsulating to aqueous phases. Indeed, current methods rely on random co-encapsulation of two aqueous phases during droplet generation or the merging of two random droplets containing different aqueous phases. In this study, we present a novel droplet microfluidic device to reliably and efficiently co-encapsulate two different aqueous phases in micro-droplets. In order to achieve this, we combined existing droplet microfluidic modules in a novel way. The different aqueous phases are individually encapsulated in droplets of different sizes. Those droplet populations are then filtered in order to position each droplet type towards its adequate trapping compartment in traps of a floating trap array. Single droplets, each containing a different aqueous phase, are thus paired and then merged. This pairing at high efficiency is achieved thanks to a unique combination of floating trap arrays, a droplet railing system and a droplet size-based filtering mechanism. The microfluidic chip design presented here provides a filtering threshold with droplets larger than 35 μm (big droplets) being deviated to the lower rail while droplets smaller than 20 μm (small droplets) remain on the upper rail. The effects of the rail height and the distance between the two (upper and lower) rails were investigated. The optimal trap dimensions provide a trapping efficiency of 100% for small and big droplets with a limited double trapping (both compartments of the traps filled with the same droplet type) of 5%. The use of electrocoalescence enables the generation of a droplet while co-encapsulating two aqueous phases. Using the presented microfluidic device libraries of 300 droplets, dual aqueous content can be generated in less than 30 min.

scholarly journals Interfacial Tension Measurements in Microfluidic Quasi-Static Extensional Flows

Micromachines ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 272
Author(s):  
Doojin Lee ◽  
Amy Q. Shen
Keyword(s):  
Interfacial Tension ◽  
Microfluidic Device ◽  
Extensional Flow ◽  
Immiscible Fluids ◽  
Droplet Microfluidics ◽  
Channel Height ◽  
Deformation Model ◽  
Droplet Deformation ◽  
Extensional Flows ◽  
2D Model

Droplet microfluidics provides a versatile tool for measuring interfacial tensions between two immiscible fluids owing to its abilities of fast response, enhanced throughput, portability and easy manipulations of fluid compositions, comparing to conventional techniques. Purely homogeneous extension in the microfluidic device is desirable to measure the interfacial tension because the flow field enables symmetric droplet deformation along the outflow direction. To do so, we designed a microfluidic device consisting of a droplet production region to first generate emulsion droplets at a flow-focusing area. The droplets are then trapped at a stagnation point in the cross junction area, subsequently being stretched along the outflow direction under the extensional flow. These droplets in the device are either confined or unconfined in the channel walls depending on the channel height, which yields different droplet deformations. To calculate the interfacial tension for confined and unconfined droplet cases, quasi-static 2D Darcy approximation model and quasi-static 3D small deformation model are used. For the confined droplet case under the extensional flow, an effective viscosity of the two immiscible fluids, accounting for the viscosity ratio of continuous and dispersed phases, captures the droplet deformation well. However, the 2D model is limited to the case where the droplet is confined in the channel walls and deforms two-dimensionally. For the unconfined droplet case, the 3D model provides more robust estimates than the 2D model. We demonstrate that both 2D and 3D models provide good interfacial tension measurements under quasi-static extensional flows in comparison with the conventional pendant drop method.

scholarly journals Negative Pressure Provides Simple and Stable Droplet Generation in a Flow-Focusing Microfluidic Device

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 662
Author(s):  
Nikita A. Filatov ◽  
Anatoly A. Evstrapov ◽  
Anton S. Bukatin
Keyword(s):  
Microfluidic Device ◽  
Negative Pressure ◽  
Low Cost ◽  
Control Valve ◽  
Droplet Microfluidics ◽  
Droplet Generation ◽  
Electric Signal ◽  
Absolute Pressure ◽  
Flow Focusing ◽  
Wide Range

Droplet microfluidics is an extremely useful and powerful tool for industrial, environmental, and biotechnological applications, due to advantages such as the small volume of reagents required, ultrahigh-throughput, precise control, and independent manipulations of each droplet. For the generation of monodisperse water-in-oil droplets, usually T-junction and flow-focusing microfluidic devices connected to syringe pumps or pressure controllers are used. Here, we investigated droplet-generation regimes in a flow-focusing microfluidic device induced by the negative pressure in the outlet reservoir, generated by a low-cost mini diaphragm vacuum pump. During the study, we compared two ways of adjusting the negative pressure using a compact electro-pneumatic regulator and a manual airflow control valve. The results showed that both types of regulators are suitable for the stable generation of monodisperse droplets for at least 4 h, with variations in diameter less than 1 µm. Droplet diameters at high levels of negative pressure were mainly determined by the hydrodynamic resistances of the inlet microchannels, although the absolute pressure value defined the generation frequency; however, the electro-pneumatic regulator is preferable and convenient for the accurate control of the pressure by an external electric signal, providing more stable pressure, and a wide range of droplet diameters and generation frequencies. The method of droplet generation suggested here is a simple, stable, reliable, and portable way of high-throughput production of relatively large volumes of monodisperse emulsions for biomedical applications.

scholarly journals Hydrodynamic Trapping of Particles in an Expansion-Contraction Microfluidic Device

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Ruijin Wang
Keyword(s):  
Reynolds Number ◽  
Microfluidic Device ◽  
Hot Spot ◽  
Force Balance ◽  
Trapping Efficiency ◽  
Particle Sizes ◽  
Particle Trapping ◽  
Particle Reynolds Number ◽  
Drag Forces ◽  
Hydrodynamic Effects

Manipulation and sorting of particles utilizing microfluidic phenomena have been a hot spot in recent years. Here, we present numerical investigations on particle trapping techniques by using intrinsic hydrodynamic effects in an expansion-contraction microfluidic device. One emphasis is on the underlying fluid dynamical mechanisms causing cross-streamlines migration of the particles in shear and vortical flows. The results show us that the expansion-contraction geometric structure is beneficial to particle trapping according to its size. Particle Reynolds number and aspect ratio of the channel will influence the trapping efficiency greatly because the force balance between inertial lift and vortex drag forces is the intrinsic reason. Especially, obvious inline particles contribution presented when the particle Reynolds number being unit. In addition, we selected three particle sizes (2, 7, and 15 μm) to examine the trapping efficiency.

scholarly journals Parameter Screening in Microfluidics Based Hydrodynamic Single-Cell Trapping

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
B. Deng ◽  
X. F. Li ◽  
D. Y. Chen ◽  
L. D. You ◽  
J. B. Wang ◽  
...  
Keyword(s):  
Single Cell ◽  
Microfluidic Device ◽  
Single Cell Analysis ◽  
Fine Tuning ◽  
Trapping Efficiency ◽  
Cell Analysis ◽  
Cell Trapping ◽  
Micro Channels ◽  
Single Cell Trapping ◽  
Trapping Sites

Microfluidic cell-based arraying technology is widely used in the field of single-cell analysis. However, among developed devices, there is a compromise between cellular loading efficiencies and trapped cell densities, which deserves further analysis and optimization. To address this issue, the cell trapping efficiency of a microfluidic device with two parallel micro channels interconnected with cellular trapping sites was studied in this paper. By regulating channel inlet and outlet status, the microfluidic trapping structure can mimic key functioning units of previously reported devices. Numerical simulations were used to model this cellular trapping structure, quantifying the effects of channel on/off status and trapping structure geometries on the cellular trapping efficiency. Furthermore, the microfluidic device was fabricated based on conventional microfabrication and the cellular trapping efficiency was quantified in experiments. Experimental results showed that, besides geometry parameters, cellular travelling velocities and sizes also affected the single-cell trapping efficiency. By fine tuning parameters, more than 95% of trapping sites were taken by individual cells. This study may lay foundation in further studies of single-cell positioning in microfluidics and push forward the study of single-cell analysis.

Free Flow Isoelectric Focusing in a Microfluidic Device

2014 ◽  
Author(s):  
Kisoo Yoo ◽  
Prashanta Dutta ◽  
Jin Liu
Keyword(s):  
Mathematical Model ◽  
Isoelectric Focusing ◽  
Microfluidic Device ◽  
Microfluidic Chip ◽  
Cardiac Troponin ◽  
Troponin I ◽  
Free Flow ◽  
Charged Species ◽  
Simulation Results ◽  
Separation Of Proteins

In recent years, there are growing interests in the use of free flow isoelectric focusing (FFIEF). In FFIEF, a thin sheath of laminar flow is introduced perpendicular to the direction of the applied electric field for continuous separation of proteins and charged species. This technique is especially useful in microfluidic device since the electrophoretically separated bands do not have to be mobilized for detection or further analysis. In this study, a mathematical model is developed to simulate free flow isoelectric process in microfluidic devices considering electroneutrality and incompressibility of electrolytes. Our mathematical model is based on mass, momentum and charge conservation equations. A finite volume based numerical scheme is implemented to simulate two dimensional FFIEF in a microfluidic chip. Simulation results indicate that pH gradient forms as samples flow downstream and proteins can be separated effectively using this technique. A new design of microfluidic chip is proposed for separation for cardiac troponin I from serum albumin using FFIEF technique.

LTCC 3D FLOW FOCALIZATION DEVICE FOR LIQUID-LIQUID PARTIAL SOLVENT EXTRACTION

2016 ◽  
Vol 2016 (CICMT) ◽  
pp. 000111-000117
Author(s):  
Houari Cobas Gomez ◽  
Jéssica Gonçalves da Silva ◽  
Jocasta Mileski Machado ◽  
Bianca Oliveira Agio ◽  
Francisco Jorge Soares de Oliveira ◽  
...  
Keyword(s):  
Solvent Extraction ◽  
Aqueous Phase ◽  
Microfluidic Device ◽  
Flow Rate ◽  
Extraction Efficiency ◽  
Channel Length ◽  
Main Channel ◽  
Process Variables ◽  
3D Flow ◽  
Acetone Concentration

Abstract The present work shows a ceramics microfluidic device for partial solvent extraction scheme. The technology used for device fabrication was Low Temperature Cofired Ceramics (LTCC) which allows us for complex and chemical resistant 3D microfluidic devices. The proposed system aims to partially extract the solvent present in a mixture containing aqueous and organic phases. This scheme uses a 3D flow focalization in order to improve the solvent diffusion into the external aqueous phase. The device is composed by three different parts, the input channels distribution, the main channel and the output channels distribution. The designed input channels distribution ensures a centered 3D focalized solvent stream along the main channel. The focalized solvent mixes with the surrounding water thanks to diffusion. Projected output channels take the central fluid out separately from the surrounding. Thus the device has two different outputs, one for the focalized fluid and another one for the waste fluid, which is the aqueous phase plus solvent. For a device concept proof, acetone and water were used as organic and aqueous phases, respectively. COMSOL Multiphysics was used for device microfluidics and chemical transport simulation. The extraction efficiency was the variable used as indicator for device performance validation. The flow rate ratio between phases, total flow rate, main channel length and focalized stream channel output hydraulic diameter (ODH) were used as process variables for simulation purposes. A factorial experimental planning was used in order to analyze the extraction efficiency taking into account process variables effects. From simulation results it was determined main channel length and ODH as the variables with stronger effect on extraction efficiency. Obtained simulated efficiencies were as high as 80.6%. Considering previous results observations a microfluidic device was fabricated with a main channel length of 21,4 mm and ODH of 214,63 μm. Gas chromatography was used to measured acetone concentration in outputs samples and from here the extraction efficiency. Experimental results were in agreement with simulation, returning extraction efficiencies in the order of 80.8% ± 2.2%.

An ultra high-efficiency droplet microfluidics platform using automatically synchronized droplet pairing and merging

Lab on a Chip ◽  
2020 ◽  
Vol 20 (21) ◽  
pp. 3948-3959 ◽  
Author(s):  
Han Zhang ◽  
Adrian R. Guzman ◽  
Jose A. Wippold ◽  
Yuwen Li ◽  
Jing Dai ◽  
...  
Keyword(s):  
High Efficiency ◽  
Droplet Microfluidics ◽  
Microfluidics Platform

The integrated droplet platform combines curved microstructures that allow high-efficiency (99.9%) reflow of droplets and a droplet cleaving that automatically synchronizes paired droplets enabling high-efficiency (99.9%) downstream merging.

scholarly journals Microfluidic on-demand droplet generation, storage, retrieval, and merging for single-cell pairing

Lab on a Chip ◽  
2019 ◽  
Vol 19 (3) ◽  
pp. 493-502 ◽  
Author(s):  
Hesam Babahosseini ◽  
Tom Misteli ◽  
Don L. DeVoe
Keyword(s):  
Single Cell ◽  
Aqueous Phase ◽  
Microfluidic Device ◽  
Droplet Generation ◽  
Microfluidic Platform ◽  
On Demand

A multifunctional microfluidic platform combining on-demand aqueous-phase droplet generation, multi-droplet storage, and controlled merging of droplets selected from a storage library in a single integrated microfluidic device is described.

scholarly journals Research on Microfluidic Chip Design and Droplet Related Technology

2020 ◽  
Vol 1520 ◽  
pp. 012003
Author(s):  
Su Zhen ◽  
Han XiaoMing ◽  
Liu QuanJun
Keyword(s):  
Microfluidic Chip ◽  
Chip Design
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