scholarly journals Rapid Microfluidic Mixing Method Based on Droplet Rotation Due to PDMS Deformation

Micromachines ◽  
2021 ◽  
Vol 12 (8) ◽  
pp. 901
Author(s):  
Chunyang Wei ◽  
Chengzhuang Yu ◽  
Shanshan Li ◽  
Feng Pan ◽  
Tiejun Li ◽  
...  
Keyword(s):  
Chemical Synthesis ◽  
Low Cost ◽  
Cross Flow ◽  
Mixing Efficiency ◽  
Mixing Index ◽  
Microfluidic Mixing ◽  
Microfluidic Mixer ◽  
Passive Micromixer ◽  
Droplet Movement ◽  
Mixing Method

Droplet-based micromixers have shown great prospects in chemical synthesis, pharmacology, biologics, and diagnostics. When compared with the active method, passive micromixer is widely used because it relies on the droplet movement in the microchannel without extra energy, which is more concise and easier to operate. Here we present a droplet rotation-based microfluidic mixer that allows rapid mixing within individual droplets efficiently. PDMS deformation is used to construct subsidence on the roof of the microchannel, which can deviate the trajectory of droplets. Thus, the droplet shows a rotation behavior due to the non-uniform distribution of the flow field, which can introduce turbulence and induce cross-flow enhancing 3D mixing inside the droplet, achieving rapid and homogenous fluid mixing. In order to evaluate the performance of the droplet rotation-based microfluidic mixer, droplets with highly viscous fluid (60% w/w PEGDA solution) were generated, half of which was seeded with fluorescent dye for imaging. Mixing efficiency was quantified using the mixing index (MI), which shows as high as 92% mixing index was achieved within 12 mm traveling. Here in this work, it has been demonstrated that the microfluidic mixing method based on the droplet rotation has shown the advantages of low-cost, easy to operate, and high mixing efficiency. It is expected to find wide applications in the field of pharmaceutics, chemical synthesis, and biologics.

Simple, Cost-Effective Fabrication, and Flow Dynamics Analysis of a Passive Microfluidic Mixer Using 3D Printing and Soft Lithography

2021 ◽  
Author(s):  
Md Fazlay Rubby ◽  
Mohammad Salman Parvez ◽  
Nazmul Islam
Keyword(s):  
3D Printing ◽  
Soft Lithography ◽  
Low Cost ◽  
Cost Effective ◽  
Flow Dynamics ◽  
Exposure System ◽  
Microfluidic Mixer ◽  
Flow Characterization ◽  
Passive Micromixer ◽  
Mask Fabrication

Abstract Simple and low-cost fabrication of microfluidic devices has attracted considerable attention among researchers. The traditional soft lithography fabrication method requires expensive equipment like a UV exposure system and mask fabrication facility. In this work, an alternative and low-cost UV exposure system was introduced along with an alternative mask fabrication system. A previously reported passive microfluidic mixer was fabricated successfully using this modified soft lithography method. Challenges were presented during this modified fabrication method. Another emerging potential alternative for the fabrication of microfluidic mixers is 3D printing. It was also used in this experiment to fabricate a passive micromixer. This method is well known for rapid prototyping and the creations of complex structures. However, this method has several disadvantages like optical transparency, lower resolution fabrication, difficulties in flow characterization, etc. These problems were addressed, and the solutions were discussed in this work. Comparative analysis between 3D printing and soft lithography fabrication was presented. Flow characterization inside the 3D printed micromixer was carried out using the microparticulate image velocimetry (micro-PIV) system. It explains how the geometrical shape of the micromixer accelerates the natural diffusion process to mix the different fluid streams. Finally, a 3D numerical simulation of the passive micromixer was carried out to visualize the flow dynamics inside the micromixer. The flow pattern found from the numerical simulation and the experimental flow characterization is analogous. These observations could play an important role to design and fabricate cost-effective micromixers for lab-on-a-chip devices.

3D-Printed Pneumatic Microfluidic Mixer for Colorimetric Detection of Listeria monocytogenes

2019 ◽  
Vol 62 (3) ◽  
pp. 841-850 ◽  
Author(s):  
Ping Yao ◽  
Ronghui Wang ◽  
Xinge Xi ◽  
Yanbin Li ◽  
Steve Tung
Keyword(s):  
Listeria Monocytogenes ◽  
3D Printing ◽  
Rapid Detection ◽  
Low Cost ◽  
Colorimetric Detection ◽  
Single Step ◽  
Mixing Efficiency ◽  
Enzyme Linked Immunosorbent Assay ◽  
Microfluidic Mixer ◽  
3D Printed

Abstract. 3D printing can significantly improve the current fabrication techniques for microfluidic devices due to its ability to create truly 3D structures in a single step. In this study, an active pneumatic microfluidic mixer was designed and fabricated using an extrusion-based 3D printer and used for rapid detection of . The printed material of the mixer is flexible, semi-transparent, and inexpensive. The fabrication time is significantly shorter than the traditional micromolding process. The printed mixer consists of two pneumatic air chambers and one mixing chamber designed for a fluidic sample size of 100 µL. The length, width, and height of the mixer chip are 13, 12.7, and 9 mm, respectively. The performance of the mixer was tested for different actuation frequencies and pneumatic pressures. The completed 3D-printed mixer was successfully applied to the colorimetric detection of for a concentration range from 102 to 108 cfu mL-1 using an enzyme-linked immunosorbent assay. The experimental results showed that the microfluidic mixer could enhance the mixing efficiency of the fluidic sample through pneumatically actuated diaphragms. In addition, the mixer could accelerate the color development caused by target , and the observed color changes could be discriminated within 5 min by naked eye. The present work will contribute to the development and optimization of a prototype for rapid detection of in food samples. It provides an effective technical approach to realize the fabrication of low-cost microfluidic chips for efficient reagent mixing in microscale biochemical detection systems. Keywords: 3D printing, Listeria monocytogenes, Microfluidic mixer, Rapid detection.

scholarly journals Novel 3-D T-Shaped Passive Micromixer Design with Helicoidal Flows

Processes ◽  
2019 ◽  
Vol 7 (9) ◽  
pp. 637 ◽  
Author(s):  
Mahmut Burak Okuducu ◽  
Mustafa M. Aral
Keyword(s):  
Fluid Flow ◽  
Fluid Mixing ◽  
Mixing Efficiency ◽  
Flow Profile ◽  
Complex Flow ◽  
Mixing Index ◽  
Micro Channels ◽  
Mixing Dynamics ◽  
Passive Micromixer ◽  
Novel Design

Laminar fluid flow and advection-dominant transport produce ineffective mixing conditions in micromixers. In these systems, a desirable fluid mixing over a short distance may be achieved using special geometries in which complex flow paths are generated. In this paper, a novel design, utilizing semi-circular ridges, is proposed to improve mixing in micro channels. Fluid flow and scalar transport are investigated employing Computational Fluid Dynamics (CFD) tool. Mixing dynamics are investigated in detail for alternative designs, injection, and diffusivity conditions. Results indicate that the convex alignment of semi-circular elements yields a specific, helicoidal-shaped fluid flow along the mixing channel which in turn enhances fluid mixing. In all cases examined, homogenous concentration distributions with mixing index values over 80% are obtained. When it is compared to the classical T-shaped micromixer, the novel design increases mixing index and mixing performance values by the factors of 8.7 and 3.3, respectively. It is also shown that different orientations of ridges adversely affect the mixing efficiency by disturbing the formation of helicoidal-shaped flow profile.

A Novel Passive Polymeric Micromixer Using 3D Porous Structure

2007 ◽  
Author(s):  
Hai Wang ◽  
Wei Li
Keyword(s):  
Focused Ultrasound ◽  
Low Cost ◽  
High Intensity Focused Ultrasound ◽  
Mixing Efficiency ◽  
Microfluidic Channels ◽  
Biological Applications ◽  
Foaming Process ◽  
Challenging Tasks ◽  
Passive Micromixer ◽  
Porous Microstructure

In microfluidic related chemical and biological applications, mixing on the micro scale is important and has been considered as one of the most challenging tasks. With a trend for polymeric microfluidic systems, a simple yet efficient passive micromixer is highly preferred [1–4]. We developed a novel passive micromixer with 3D porous microstructure on a polymer chip. The fabrication process uses high-intensity focused ultrasound to selectively foam gas-impregnated polymers. The selective ultrasonic foaming technique is simple, low-cost, and biocompatible. The porous microstructure is easily controlled by adjusting the parameters of the ultrasonic foaming process. The 3D porous microstructure can split, stretch, fold and break the mixing flows in microfluidic channels and thus dramatically improve the mixing efficiency.

scholarly journals Exploring and Exploiting the Symmetry-Breaking Effect of Cyclodextrins in Mechanomolecules

Symmetry ◽  
2019 ◽  
Vol 11 (10) ◽  
pp. 1249 ◽  
Author(s):  
Bruns
Keyword(s):  
Symmetry Breaking ◽  
Chemical Synthesis ◽  
Low Cost ◽  
Molecular Machine ◽  
Advanced Materials ◽  
Breaking Effect ◽  
Planar Chirality ◽  
Conical Shape ◽  
Wide Availability ◽  
Molecular Rings

Cyclodextrins (CDs) are cone-shaped molecular rings that have been widely employed in supramolecular/host–guest chemistry because of their low cost, high biocompatibility, stability, wide availability in multiple sizes, and their promiscuity for binding a range of molecular guests in water. Consequently, CD-based host–guest complexes are often employed as templates for the synthesis of mechanically bonded molecules (mechanomolecules) such as catenanes, rotaxanes, and polyrotaxanes in particular. The conical shape and cyclodirectionality of the CD “bead” gives rise to a symmetry-breaking effect when it is threaded onto a molecular “string”; even symmetrical guests are rendered asymmetric by the presence of an encircling CD host. This review focuses on the stereochemical implications of this symmetry-breaking effect in mechanomolecules, including orientational isomerism, mechanically planar chirality, and topological chirality, as well as how they support applications in regioselective and stereoselective chemical synthesis, the design of molecular machine prototypes, and the development of advanced materials.

Fabrication of Tunable Silk Materials Through Microfluidic Mixers

2016 ◽  
Author(s):  
Joseph R. Nalbach ◽  
Dave Jao ◽  
Douglas G. Petro ◽  
Kyle M. Raudenbush ◽  
Shibbir Ahmad ◽  
...  
Keyword(s):  
Soft Lithography ◽  
Mixing Processes ◽  
Microfluidic Mixing ◽  
Microfluidic Mixer ◽  
Continuous Mixing ◽  
Mixing Performance ◽  
3D Printed ◽  
Distribution Uniformity ◽  
Mixing Patterns ◽  
Microfluidic Mixers

A common method to precisely control the material properties is to evenly distribute functional nanomaterials within the substrate. For example, it is possible to mix a silk solution and nanomaterials together to form one tuned silk sample. However, the nanomaterials are likely to aggregate in the traditional manual mixing processes. Here we report a pilot study of utilizing specific microfluidic mixing designs to achieve a uniform nanomaterial distribution with minimal aggregation. Mixing patterns are created based on classic designs and then validated by experimental results. The devices are fabricated on polydimethylsiloxane (PDMS) using 3D printed molds and soft lithography for rapid replication. The initial mixing performance is validated through the mixing of two solutions with colored dyes. The microfluidic mixer designs are further analyzed by creating silk-based film samples. The cured film is inspected with scanning electron microscopy (SEM) to reveal the distribution uniformity of the dye particles within the silk material matrix. Our preliminary results show that the microfluidic mixing produces uniform distribution of dye particles. Because the microfluidic device can be used as a continuous mixing tool, we believe it will provide a powerful platform for better preparation of silk materials. By using different types of nanomaterials such as graphite (demonstrated in this study), graphene, carbon nanotubes, and magnetic nanoparticles, the resulting silk samples can be fine-tuned with desired electrical, mechanical, and magnetic properties.

An Enhanced One-Layer Passive Microfluidic Mixer With an Optimized Lateral Structure With the Dean Effect

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Teng Zhou ◽  
Yifan Xu ◽  
Zhenyu Liu ◽  
Sang Woo Joo
Keyword(s):  
Reynolds Number ◽  
Topology Optimization ◽  
Optimization Method ◽  
Mixing Efficiency ◽  
Boolean Operation ◽  
Microfluidic Mixer ◽  
Wide Range ◽  
The One ◽  
Lateral Structure ◽  
Topology Optimization Method

Topology optimization method is applied to a contraction–expansion structure, based on which a simplified lateral flow structure is generated using the Boolean operation. A new one-layer mixer is then designed by sequentially connecting this lateral structure and bent channels. The mixing efficiency is further optimized via iterations on key geometric parameters associated with the one-layer mixer designed. Numerical results indicate that the optimized mixer has better mixing efficiency than the conventional contraction–expansion mixer for a wide range of the Reynolds number.

Numerical analysis of non-aligned inputs M-type micromixers with different shaped obstacles for biomedical applications

2021 ◽  
pp. 095440892110516
Author(s):  
Muhammad Irfan ◽  
Imran Shah ◽  
Usama M Niazi ◽  
Muhsin Ali ◽  
Sadaqat Ali ◽  
...  
Keyword(s):  
Structural Design ◽  
Biomedical Applications ◽  
Structural Changes ◽  
Nanoparticle Synthesis ◽  
Fluid Mixing ◽  
The Novel ◽  
Flow Conditions ◽  
Mixing Index ◽  
Mixing Performance ◽  
Passive Micromixer

Fluid mixing in lab-on-a-chip devices at laminar flow conditions result in a low mixing index. The reason is dominant diffusion over the convection process. The mixing index can be improved by certain changes in the micromixer structural design like introducing obstacles in the path of fluid flow. These obstacles will make dominant the advection process over the diffusion process. The main contribution of this work is based on proposing the novel hybrid type micromixer design for enhancing the mixing quality. Three non-aligned M-type and non-aligned M-type with obstacles passive type micromixers are analyzed by COMSOL5.5. These designs are hybrid types because different structural changes are combined in a single design for mixing improvement. First of all the straight non-aligned inlets, M-type passive micromixer (SMTM) is analyzed. It is observed that mixing performance is improved because of M-shaped mixing units and non-aligned inlets. This improvement is deemed to be not enough so different shaped obstacles are introduced in the micromixer design. These designs based on obstacles are named horizontal rectangular M-type micromixer, square M-type micromixer, and vertical rectangular M-type micromixer. The mixing index for SMTM, square M-type micromixer, horizontal rectangular M-type micromixer, and vertical rectangular M-type micromixer at Reynolds number Re = 60 is respectively given by 71.1%, 83.21%, 84.45%, and 89.99%. The mixing index of vertical rectangular M-type micromixer was 59.34% − 87.65% for Re = 0.5–100. Vertical rectangular M-type micromixer is concluded with the better-mixing capability design among the proposed ones. Based on these simulation results, the vertical rectangular M-type micromixer design can be utilized for mixing purposes in biomedical applications like nanoparticle synthesis and biomedical sample preparation for drug delivery.

The Influence of Sodium Bicarbonate Loading as Blowing Agent on the Properties of Epoxy Foam

2018 ◽  
Vol 280 ◽  
pp. 270-276 ◽  
Author(s):  
Mohamad Saed Hussein ◽  
Teh Pei Leng ◽  
Abdul Razak Rahmat ◽  
Firuz Zainuddin ◽  
Yeoh Chow Keat
Keyword(s):  
Sodium Bicarbonate ◽  
Low Cost ◽  
Flexural Properties ◽  
Foaming Agent ◽  
Blowing Agent ◽  
Environmental Friendly ◽  
Epoxy Foam ◽  
Mixing Method ◽  
Porosity Percentage ◽  
Thermosetting Epoxy

This research studied the effect of sodium bicarbonate content on the properties of epoxy. Sodium bicarbonate (SB) was used as foaming agent to improve the properties of thermosetting epoxy resin. The samples of epoxy foam were produced using mixing method. Sodium bicarbonate was selected as blowing agent by reason of the environmental friendly and low cost concern. Mechanical, physical and morphology properties were done. Sodium bicarbonate content was varied at 5, 10, 15, 20 and 25 part per hundred (phr), respectively. It can be highlighted that the optimum content of the SB was selected at 15 phr and it gave the moderate porosity percentage (%), and moderate value in mechanical and density properties, higher SB content exhibited lower flexural properties.

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