Rapid fabrication of circular channel microfluidic flow‐focusing devices for hydrogel droplet generation

2016 ◽  
Vol 11 (1) ◽  
pp. 41-45 ◽  
Author(s):  
Benjamin Parker ◽  
Roya Samanipour ◽  
Ali Ahmadi ◽  
Keekyoung Kim
Keyword(s):  
Droplet Generation ◽  
Circular Channel ◽  
Flow Focusing ◽  
Microfluidic Flow ◽  
Rapid Fabrication

scholarly journals Breakup Dynamics of Semi-dilute Polymer Solutions in a Microfluidic Flow-focusing Device

Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 406
Author(s):  
Chun-Dong Xue ◽  
Xiao-Dong Chen ◽  
Yong-Jiang Li ◽  
Guo-Qing Hu ◽  
Tun Cao ◽  
...  
Keyword(s):  
Relaxation Time ◽  
Polymer Solutions ◽  
Newtonian Fluids ◽  
Droplet Microfluidics ◽  
Droplet Generation ◽  
Flow Focusing ◽  
Polymeric Fluids ◽  
Practical Applications ◽  
Dilute Polymer Solutions ◽  
Microfluidic Flow

Droplet microfluidics involving non-Newtonian fluids is of great importance in both fundamental mechanisms and practical applications. In the present study, breakup dynamics in droplet generation of semi-dilute polymer solutions in a microfluidic flow-focusing device were experimentally investigated. We found that the filament thinning experiences a transition from a flow-driven to a capillary-driven regime, analogous to that of purely elastic fluids, while the highly elevated viscosity and complex network structures in the semi-dilute polymer solutions induce the breakup stages with a smaller power-law exponent and extensional relaxation time. It is elucidated that the elevated viscosity of the semi-dilute solution decelerates filament thinning in the flow-driven regime and the incomplete stretch of polymer molecules results in the smaller extensional relaxation time in the capillary-driven regime. These results extend the understanding of breakup dynamics in droplet generation of non-Newtonian fluids and provide guidance for microfluidic synthesis applications involving dense polymeric fluids.

Electrowetting-controlled droplet generation in a microfluidic flow-focusing device

2007 ◽  
Vol 19 (46) ◽  
pp. 462101 ◽  
Author(s):  
Florent Malloggi ◽  
Siva A Vanapalli ◽  
Hao Gu ◽  
Dirk van den Ende ◽  
Frieder Mugele
Keyword(s):  
Droplet Generation ◽  
Flow Focusing ◽  
Microfluidic Flow

Effect of Intersection Angle and Wettability on Droplet Generation in Microfluidic Flow-Focusing Device

2020 ◽  
Vol 142 (4) ◽  
Author(s):  
Saima Iqbal ◽  
Shazia Bashir ◽  
Muhammad Ahsan ◽  
Muhammad Bashir ◽  
Saad Shoukat
Keyword(s):  
Contact Angle ◽  
Droplet Breakup ◽  
Droplet Generation ◽  
Maximum Diameter ◽  
Generation Process ◽  
Flow Focusing ◽  
Intersection Angle ◽  
Droplet Shape ◽  
Vof Model ◽  
Microfluidic Flow

Abstract This article investigates the dynamics of droplet generation process in a microfluidic flow-focusing device under the effect of geometry altered by the intersection angle (φ), which the flanking inlets make with central inlet and wall wettability quantified by the contact angle (θ) using volume of fluid (VOF) model. These parameters have been found to alter the droplet shape and size greatly. The effect of intersection angles has been examined for φ = 15 deg, 30 deg, 45 deg, 60 deg, 90 deg, and 120 deg for generating size-controlled droplets. It was predicted that the diameter of droplet increased with the increase in intersection angle (φ = 15 deg, 30 deg, 45 deg, 60 deg, 90 deg, and 120 deg) and the maximum diameter has been generated at φ = 90. In addition, the wetting characteristics (hydrophilic to hydrophobic) have been studied numerically in detail by changing the contact angle of the dispersed phase with the channel wall ranging from 90 deg to 180 deg. It was indicated that the droplets of rectangular shape are formed in hydrophilic channel by completely wetting the wall when θ ≤ 90 deg. They transform their shape to slightly oval form with the increase in contact angle and start acquiring spherical shape when the channel becomes hydrophobic. Furthermore, Parameters such as dimensionless droplet diameter, droplet shape, and droplet breakup time have also been investigated extensively for flowrate ratios Q = 0.125, 0.25, 0.5, and 1, in order to optimize the microfluidic device.

Negative Pressure Induced Droplet Generation in a Microfluidic Flow-Focusing Device

2017 ◽  
Vol 89 (8) ◽  
pp. 4387-4391 ◽  
Author(s):  
Adrian J. T. Teo ◽  
King-Ho Holden Li ◽  
Nam-Trung Nguyen ◽  
Wei Guo ◽  
Nadine Heere ◽  
...  
Keyword(s):  
Negative Pressure ◽  
Droplet Generation ◽  
Flow Focusing ◽  
Microfluidic Flow

Microneedle-assisted microfluidic flow focusing for versatile and high throughput water-in-water droplet generation

2019 ◽  
Vol 553 ◽  
pp. 382-389 ◽  
Author(s):  
Morteza Jeyhani ◽  
Vaskar Gnyawali ◽  
Niki Abbasi ◽  
Dae Kun Hwang ◽  
Scott S.H. Tsai
Keyword(s):  
High Throughput ◽  
Water Droplet ◽  
Droplet Generation ◽  
Flow Focusing ◽  
Microfluidic Flow

scholarly journals Modeling of Droplet Generation in a Microfluidic Flow-Focusing Junction for Droplet Size Control

Micromachines ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 590
Author(s):  
Ali M. Ibrahim ◽  
Jose I. Padovani ◽  
Roger T. Howe ◽  
Yasser H. Anis
Keyword(s):  
Numerical Model ◽  
Droplet Size ◽  
Size Control ◽  
Continuous Phase ◽  
Immiscible Fluids ◽  
Droplet Generation ◽  
Flow Rate Ratio ◽  
Flow Focusing ◽  
Flow Rates ◽  
Microfluidic Flow

In this paper, we study the parameters that affect the generation of droplets in a microfluidic flow-focusing junction. Droplets are evaluated based on the size and frequency of generation. Droplet size control is essential for microfluidic lab-on-a-chip applications in biology, chemistry, and medicine. We developed a three-dimensional numerical model that can emulate the performance of the physical system. A numerical model can help design droplet-generation chips with new junction geometries, different dispersed and continuous phase types, and different flow rates. Our model uses a conservative level-set method (LSM) to track the interface between two immiscible fluids using a fixed mesh. Water was used for the dispersed phase and mineral oil for the continuous phase. The effects of the continuous-to-dispersed flow rate ratio (Qo/Qw) and the surfactant concentration on the droplet generation were studied both using the numerical model and experimentally. The numerical model was found to render results that are in good agreement with the experimental ones, which validates the LSM model. The validated numerical model was used to study the time effect of changing Qo/Qw on the generated droplet size. Properly timing when the flow rates are changed enables control over the size of the next generated droplet, which is useful for single-droplet size modulation applications.

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.

Formation of Polyacrylamide and PEGDA Hydrogel Particles in a Microfluidic Flow Focusing Droplet Generator

2018 ◽  
Vol 63 (9) ◽  
pp. 1328-1333
Author(s):  
D. V. Nozdriukhin ◽  
N. A. Filatov ◽  
A. A. Evstrapov ◽  
A. S. Bukatin
Keyword(s):  
Droplet Generator ◽  
Flow Focusing ◽  
Hydrogel Particles ◽  
Microfluidic Flow
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