Special Issue "Analysis, Design and Fabrication of Micromixers"

A special issue of Micromachines (ISSN 2072-666X). This special issue belongs to the section "A:Physics".

Deadline for manuscript submissions: 30 November 2020.

Special Issue Editor

Prof. Dr. Kwang-Yong Kim
Website SciProfiles
Guest Editor
Department of Mechanical Engineering, Inha University, Incheon, 22212, Korea
Interests: micromixer; micro heat sink; fluid machinery; optimization; heat transfer
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Micromixers are an important component in micrototal analysis systems and lab-on-a-chip platforms which are widely used for sample preparation and analysis, drug delivery, and biological and chemical synthesis. The successful operation of microfluidic devices requires fast and adequate mixing, but mixing is a challenging task due to the laminar feature of the flow at the microscale. Mixing in laminar flows relies on diffusion and requires a longer channel to achieve complete mixing due to the slow process compared to that in turbulent flows. Hence, it is crucial to overcome this challenge to improve the mixing performance. Based on their mixing mechanism, micromixers are classified into two types: active and passive. Passive micromixers are easy to fabricate and generally use geometry modification to cause chaotic advection or lamination to promote the mixing of fluid samples, unlike active micromixers, which use moving parts or some external agitation/energy for the mixing. The current Special Issue covers new mechanisms, numerical and/or experimental mixing analysis, design, and fabrication of various micromixers.

Prof. Kwang-Yong Kim
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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Keywords

  • micromixer
  • mixing
  • microfluidic device
  • analysis
  • design
  • fabrication

Published Papers (4 papers)

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Research

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Open AccessArticle
Mechanical Characterisation and Analysis of a Passive Micro Heat Exchanger
Micromachines 2020, 11(7), 668; https://doi.org/10.3390/mi11070668 - 09 Jul 2020
Abstract
Heat exchangers are widely used in many mechanical, electronic, and bioengineering applications at macro and microscale. Among these, the use of heat exchangers consisting of a single fluid passing through a set of geometries at different temperatures and two flows in T-shape channels [...] Read more.
Heat exchangers are widely used in many mechanical, electronic, and bioengineering applications at macro and microscale. Among these, the use of heat exchangers consisting of a single fluid passing through a set of geometries at different temperatures and two flows in T-shape channels have been extensively studied. However, the application of heat exchangers for thermal mixing over a geometry leading to vortex shedding has not been investigated. This numerical work aims to analyse and characterise a heat exchanger for microscale application, which consists of two laminar fluids at different temperature that impinge orthogonally onto a rectangular structure and generate vortex shedding mechanics that enhance thermal mixing. This work is novel in various aspects. This is the first work of its kind on heat transfer between two fluids (same fluid, different temperature) enhanced by vortex shedding mechanics. Additionally, this research fully characterise the underlying vortex mechanics by accounting all geometry and flow regime parameters (longitudinal aspect ratio, blockage ratio and Reynolds number), opposite to the existing works in the literature, which usually vary and analyse blockage ratio or longitudinal aspect ratio only. A relevant advantage of this heat exchanger is that represents a low-Reynolds passive device, not requiring additional energy nor moving elements to enhance thermal mixing. This allows its use especially at microscale, for instance in biomedical/biomechanical and microelectronic applications. Full article
(This article belongs to the Special Issue Analysis, Design and Fabrication of Micromixers)
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Open AccessArticle
Understanding Interdependencies between Mechanical Velocity and Electrical Voltage in Electromagnetic Micromixers
Micromachines 2020, 11(7), 636; https://doi.org/10.3390/mi11070636 - 29 Jun 2020
Abstract
Micromixers are critical components in the lab-on-a-chip or micro total analysis systems technology found in micro-electro-mechanical systems. In general, the mixing performance of the micromixers is determined by characterising the mixing time of a system, for example the time or number of circulations [...] Read more.
Micromixers are critical components in the lab-on-a-chip or micro total analysis systems technology found in micro-electro-mechanical systems. In general, the mixing performance of the micromixers is determined by characterising the mixing time of a system, for example the time or number of circulations and vibrations guided by tracers (i.e., fluorescent dyes). Our previous study showed that the mixing performance could be detected solely from the electrical measurement. In this paper, we employ electromagnetic micromixers to investigate the correlation between electrical and mechanical behaviours in the mixer system. This work contemplates the “anti-reciprocity” concept by providing a theoretical insight into the measurement of the mixer system; the work explains the data interdependence between the electrical point impedance (voltage per unit current) and the mechanical velocity. This study puts the electromagnetic micromixer theory on a firm theoretical and empirical basis. Full article
(This article belongs to the Special Issue Analysis, Design and Fabrication of Micromixers)
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Open AccessArticle
Technical Model of Micro Electrical Discharge Machining (EDM) Milling Suitable for Bottom Grooved Micromixer Design Optimization
Micromachines 2020, 11(6), 594; https://doi.org/10.3390/mi11060594 - 16 Jun 2020
Abstract
In this paper, development of a technical model of micro Electrical Discharge Machining in milling configuration (EDM milling) is presented. The input to the model is a parametrically presented feature geometry and the output is a feature machining time. To model key factors [...] Read more.
In this paper, development of a technical model of micro Electrical Discharge Machining in milling configuration (EDM milling) is presented. The input to the model is a parametrically presented feature geometry and the output is a feature machining time. To model key factors influencing feature machining time, an experimental campaign by machining various microgrooves into corrosive resistant steel was executed. The following parameters were investigated: electrode dressing time, material removal rate, electrode wear, electrode wear control time and machining strategy. The technology data and knowledge base were constructed using data obtained experimentally. The model is applicable for groove-like features, commonly applied in bottom grooved micromixers (BGMs), with widths from 40 to 120 µm and depths up to 100 µm. The optimization of a BGM geometry is presented as a case study of the model usage. The mixing performances of various micromixer designs, compliant with micro EDM milling technology, were evaluated using computational fluid dynamics modelling. The results show that slanted groove micromixer is a favourable design to be implemented when micro EDM milling technology is applied. The presented technical model provides an efficient design optimization tool and, thus, aims to be used by a microfluidic design engineer. Full article
(This article belongs to the Special Issue Analysis, Design and Fabrication of Micromixers)
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Review

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Open AccessReview
A Review of Passive Micromixers with a Comparative Analysis
Micromachines 2020, 11(5), 455; https://doi.org/10.3390/mi11050455 - 27 Apr 2020
Abstract
A wide range of existing passive micromixers are reviewed, and quantitative analyses of ten typical passive micromixers were performed to compare their mixing indices, pressure drops, and mixing costs under the same axial length and flow conditions across a wide Reynolds number range [...] Read more.
A wide range of existing passive micromixers are reviewed, and quantitative analyses of ten typical passive micromixers were performed to compare their mixing indices, pressure drops, and mixing costs under the same axial length and flow conditions across a wide Reynolds number range of 0.01–120. The tested micromixers were selected from five types of micromixer designs. The analyses of flow and mixing were performed using continuity, Navier-Stokes and convection-diffusion equations. The results of the comparative analysis were presented for three different Reynolds number ranges: low-Re (Re ≤ 1), intermediate-Re (1 < Re ≤ 40), and high-Re (Re > 40) ranges, where the mixing mechanisms are different. The results show a two-dimensional micromixer of Tesla structure is recommended in the intermediate- and high-Re ranges, while two three-dimensional micromixers with two layers are recommended in the low-Re range due to their excellent mixing performance. Full article
(This article belongs to the Special Issue Analysis, Design and Fabrication of Micromixers)
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