scholarly journals Controlling Shapes in a Coaxial Flow Focusing Microfluidic Device: Experiments and Theory

Micromachines ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 85
Author(s):  
Romen Rodriguez-Trujillo ◽  
Yu-Han Kim-Im ◽  
Aurora Hernandez-Machado
Keyword(s):  
Microfluidic Device ◽  
Soft Lithography ◽  
Flow Rate Ratio ◽  
Flow Focusing ◽  
Outer Flow ◽  
Flow Rates ◽  
Fluorescein Solution ◽  
Elliptical Section ◽  
Additional Water ◽  
And Control

A coaxial flow focusing PDMS (polydimethylsiloxane) microfluidic device has been designed and manufactured by soft lithography in order to experimentally study a miscible inner flow. We studied a coaxially focused inner flow (formed by an aqueous fluorescein solution) which was fully isolated from all microchannel surfaces by an additional water outer flow. Different flow rates were used to produce a variety of flow ratios and a 3D reconstruction of the cross-section was performed using confocal microscope images. The results showed an elliptical section of the coaxially focused inner flow that changes in shape depending on the flow rate ratio applied. We have also developed a mathematical model that allows us to predict and control the geometry of the coaxially focused inner flow.

A Computational Study of Drop Formation in an Axisymmetric Flow-Focusing Device

2006 ◽  
Author(s):  
Ismail Filiz ◽  
Metin Muradoglu
Keyword(s):  
Drop Size ◽  
Viscosity Ratio ◽  
Computational Study ◽  
Axisymmetric Flow ◽  
Front Tracking ◽  
Drop Formation ◽  
Flow Focusing ◽  
Outer Flow ◽  
Flow Rates ◽  
Creation Process

We investigate the formation and dynamics of drops computationally in an axisymetric geometry using a Front-Tracking/Finite-Difference (FT/FD) method. The effects of viscosity ratio between inner and outer liquids on the drop creation process and drop size distribution are examined. It is found that the viscosity ratio critically influences the drop formation process and the final drop distribution. We found that, for small viscosity ratios, i.e., 0.1 < λ < 0.5 drop size is about the size of the orifice and drop distribution is highly monodisperse. When viscosity ratio is increased, i.e., 0.5 < λ < 1 a smaller drop is created just after the main drop. For even higher viscosity ratios, the drop distribution is usually monodisperse but a satellite drop is created in some cases. The effect of the flow rates in the inner jet and the co flowing annulus are also studied. It is found that the drop size gets smaller as Qin / Qout is reduced while keeping the outer flow rate constant.

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.

Erratum — Universal method for fabricating PDMS microfluidic device using SU8, 3D printing and soft lithography

2021 ◽  
pp. 1-1
Author(s):  
Charmi Chande ◽  
Nida Riaz ◽  
Andrew House ◽  
Victoria Harbour ◽  
Hathija Noor ◽  
...  
Keyword(s):  
3D Printing ◽  
Microfluidic Device ◽  
Soft Lithography ◽  
Universal Method

scholarly journals Micropipette-Based Microfluidic Device for Monodisperse Microbubbles Generation

Micromachines ◽  
2018 ◽  
Vol 9 (8) ◽  
pp. 387
Author(s):  
Carlos Toshiyuki Matsumi ◽  
Wilson José da Silva ◽  
Fábio Kurt Schneider ◽  
Joaquim Miguel Maia ◽  
Rigoberto E. M. Morales ◽  
...  
Keyword(s):  
Electric Fields ◽  
Microfluidic Device ◽  
Soft Lithography ◽  
Low Cost ◽  
Characteristic Curve ◽  
Microfluidic Devices ◽  
Average Diameter ◽  
Internal Diameter ◽  
Medical Diagnostic ◽  
Average Size

Microbubbles have various applications including their use as carrier agents for localized delivery of genes and drugs and in medical diagnostic imagery. Various techniques are used for the production of monodisperse microbubbles including the Gyratory, the coaxial electro-hydrodynamic atomization (CEHDA), the sonication methods, and the use of microfluidic devices. Some of these techniques require safety procedures during the application of intense electric fields (e.g., CEHDA) or soft lithography equipment for the production of microfluidic devices. This study presents a hybrid manufacturing process using micropipettes and 3D printing for the construction of a T-Junction microfluidic device resulting in simple and low cost generation of monodisperse microbubbles. In this work, microbubbles with an average size of 16.6 to 57.7 μm and a polydispersity index (PDI) between 0.47% and 1.06% were generated. When the device is used at higher bubble production rate, the average diameter was 42.8 μm with increased PDI of 3.13%. In addition, a second-order polynomial characteristic curve useful to estimate micropipette internal diameter necessary to generate a desired microbubble size is presented and a linear relationship between the ratio of gaseous and liquid phases flows and the ratio of microbubble and micropipette diameters (i.e., Qg/Ql and Db/Dp) was found.

scholarly journals The Combined Effects of Co-Culture and Substrate Mechanics on 3D Tumor Spheroid Formation within Microgels Prepared via Flow-Focusing Microfluidic Fabrication

Pharmaceutics ◽  
2018 ◽  
Vol 10 (4) ◽  
pp. 229 ◽  
Author(s):  
Dongjin Lee ◽  
Chaenyung Cha
Keyword(s):  
Mechanical Properties ◽  
Cell Culture ◽  
Microfluidic Device ◽  
3D Cell Culture ◽  
Breast Adenocarcinoma ◽  
Adherent Cell ◽  
Flow Focusing ◽  
Spheroid Formation ◽  
3D Scaffold ◽  
Tumor Spheroids

Tumor spheroids are considered a valuable three dimensional (3D) tissue model to study various aspects of tumor physiology for biomedical applications such as tissue engineering and drug screening as well as basic scientific endeavors, as several cell types can efficiently form spheroids by themselves in both suspension and adherent cell cultures. However, it is more desirable to utilize a 3D scaffold with tunable properties to create more physiologically relevant tumor spheroids as well as optimize their formation. In this study, bioactive spherical microgels supporting 3D cell culture are fabricated by a flow-focusing microfluidic device. Uniform-sized aqueous droplets of gel precursor solution dispersed with cells generated by the microfluidic device are photocrosslinked to fabricate cell-laden microgels. Their mechanical properties are controlled by the concentration of gel-forming polymer. Using breast adenocarcinoma cells, MCF-7, the effect of mechanical properties of microgels on their proliferation and the eventual spheroid formation was explored. Furthermore, the tumor cells are co-cultured with macrophages of fibroblasts, which are known to play a prominent role in tumor physiology, within the microgels to explore their role in spheroid formation. Taken together, the results from this study provide the design strategy for creating tumor spheroids utilizing mechanically-tunable microgels as 3D cell culture platform.

A Multifunctional Microfluidic Device Based on Bifurcation Geometry

2010 ◽  
Author(s):  
Ahmed Fadl ◽  
Stefanie Demming ◽  
Zongqin Zhang ◽  
Bjo¨rn Hoxhold ◽  
Stephanus Bu¨ttgenbach ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Microfluidic Devices ◽  
Optical Lithography ◽  
Working Fluid ◽  
The Novel ◽  
Flow Rates ◽  
Single Function ◽  
Fluidic Device ◽  
Bifurcation Structures ◽  
Novel Design

Developing multifunctional devices are essential to realize more efficient Microsystems. With miniaturization processes taking place in many different applications, the rooms for single function microfluidic devices are limited. In this study, we introduce a multifunctional micro fluidic device based on bifurcation geometry which is capable of performing pumping and mixing at the same time. Optical lithography is used to fabricate the designed microfluidic device. The microfluidic device is tested at low actuator frequencies, and ethanol is employed as a working fluid. The operational principles are based on rectifying the oscillatory flows by using bifurcation structures for flow rectification. The results prove the feasibility of the novel design, and results are presented in terms of flow rates and maximum back pressures.

Fabrication of Microfluidic Manifold by Precision Extrusion Deposition and Replica Molding for Cell-Laden Device

2015 ◽  
Vol 138 (4) ◽  
Author(s):  
Jessica Snyder ◽  
Ae Rin Son ◽  
Qudus Hamid ◽  
Wei Sun
Keyword(s):  
Microfluidic Device ◽  
Molding Process ◽  
Channel Network ◽  
Embedded Networks ◽  
Replica Molding ◽  
Cell Printing ◽  
Construction Methods ◽  
Cell Placement ◽  
And Control ◽  
Guided Tissue Engineering

A PED (precision extrusion deposition)/replica molding process enables scaffold guided tissue engineering of a heterocellular microfluidic device. We investigate two types of cell-laden devices: the first with a 3D microfluidic manifold fully embedded in a PDMS (polydimethylsiloxane) substrate and the second a channel network on the surface of the PDMS substrate for cell printing directly into device channels. Fully embedded networks are leak-resistant with simplified construction methods. Channels exposed to the surface are used as mold to hold bioprinted cell-laden matrix for controlled cell placement throughout the network from inlet to outlet. The result is a 3D cell-laden microfluidic device with improved leak-resistance (up to 2.0 mL/min), pervasive diffusion and control of internal architecture.

Characterizing the High Reynolds Number Regime for Deterministic Lateral Displacement (DLD) Devices

2017 ◽  
Author(s):  
Brian Dincau ◽  
Arian Aghilinejad ◽  
Jong-Hoon Kim ◽  
Xiaolin Chen
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Soft Lithography ◽  
Lateral Displacement ◽  
Flow Characteristics ◽  
Critical Diameter ◽  
Flow Rates ◽  
Deterministic Lateral Displacement ◽  
Array Configuration ◽  
High Reynolds

Deterministic lateral displacement (DLD) is a common name given to a class of continuous microfluidic separation devices that use a repeating array of pillars to selectively displace particles having a mean diameter greater than the critical diameter (Dc). This Dc is an emergent property influenced by pillar shape, size, and spacing, in addition to the suspending fluid and target particle properties. The majority of previous research in DLD applications has focused on the utilization of laminar flow in low Reynolds number (Re) regimes. While laminar flow exhibits uniform streamlines and predictable separation characteristics, this low-Re regime is dependent on relatively low fluid velocities, and may not hold true at higher processing speeds. Through numerical modeling and experimentation, we investigated high-Re flow characteristics and potential separation enhancements resulting from vortex generation within a DLD array. We used an analytical model and computational software to simulate DLD performance spanning a Re range of 1–100 at flow rates of 2–170 μL/s (0.15–10 mL/min). Each simulated DLD array configuration was composed of 60 μm cylindrical pillars with a 45 μm gap size. The experimental DLD device was fabricated using conventional soft lithography, and injected with 20 μm particles at varying flow rates to observe particle trajectories. The simulated results predict a shift in Dc at Re > 50, while the experimental results indicate a breakdown of typical DLD operation at Re > 70.

3D FOCALIZATION MICROFLUIDIC DEVICE BUILT WITH LTCC TECHNOLOGY FOR NANOPARTICLE GENERATION USING NANOPRECIPITATION ROUTE

2015 ◽  
Vol 2015 (CICMT) ◽  
pp. 000275-000280 ◽  
Author(s):  
Houari Cobas Gomez ◽  
Mario Ricardo Gongora-Rubio ◽  
Bianca Oliveira Agio ◽  
Vanessa Tiemi Kimura ◽  
Adriano Marim de Oliveira ◽  
...  
Keyword(s):  
Microfluidic Device ◽  
Chemical Process ◽  
Chemical Processes ◽  
Polydispersity Index ◽  
Flow Focusing ◽  
Enabling Technology ◽  
Fine Chemistry ◽  
Excellent Control ◽  
Microsystem Technologies ◽  
Nanoparticle Generation

Nanoprecipitation is a nanonization technique used for nanoparticle generation. Several fields, like pharmacology and fine chemistry, make use of such technique. Typically are used a bulky batch mechanical processes rendering high polydispersity index of generated nanoparticles, poorly particle size reproducibility and energy wasting. LTCC-based microsystem technologies allow the implementation of different unitary operations for chemical process, making it an enabling technology for the miniaturization of chemical processes. In fact, recently LTCC microfluidic reactors have been used to produce micro and nanoparticles with excellent control of size distribution and morphology. The present work provides a report on the performance of a 3D LTCC flow focusing Microfluidic device designed to fabricate polymeric nanocapsules for Hydrocortisone drug encapsulation, using nanoprecipitation route. Monodisperse Hydrocortisone nanocapsules were obtained with sizes (Tp) from 188.9 nm to 459.1 nm with polydispersity index (PDI) from 0.102 to 0.235.

Sign in / Sign up

Export Citation Format

Share Document