Blood Flow Visualization and Measurements in Microfluidic Devices Fabricated by a Micromilling Technique
TL;DR: In this article, the authors acknowledge the financial support provided by PTDC/SAU-ENB/116929/2010 and EXPL/EMS-SIS/6762215/2013 from FCT (Science and Technology Foundation), COMPETE, QREN and European Union (FEDER).
Abstract: The authors acknowledge the financial support provided
by PTDC/SAU-ENB/116929/2010 and EXPL/EMS-SIS/
2215/2013 from FCT (Science and Technology Foundation),
COMPETE, QREN and European Union (FEDER). DP acknowledge
the PhD scholarship SFRH/BD/89077/2012, and
P.C. Sousa acknowledges the fellowship SFRH/BPD/75258/
2010, all attributed by FCT.
Citations
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TL;DR: In this review, a selection of the most recent lithographic and non-lithographic low-cost techniques to fabricate microfluidic structures, focused on the features and limitations of each technique.
235 citations
TL;DR: An overview of the microfabrication techniques is given, especially for biomedical applications, as well as a synopsis of some design considerations regarding microfluidic devices.
Abstract: Since the first microfluidic device was developed more than three decades ago, microfluidics is seen as a technology that exhibits unique features to provide a significant change in the way that modern biology is performed. Blood and blood cells are recognized as important biomarkers of many diseases. Taken advantage of microfluidics assets, changes on blood cell physicochemical properties can be used for fast and accurate clinical diagnosis. In this review, an overview of the microfabrication techniques is given, especially for biomedical applications, as well as a synopsis of some design considerations regarding microfluidic devices. The blood cells separation and sorting techniques were also reviewed, highlighting the main achievements and breakthroughs in the last decades.
89 citations
TL;DR: Emulsion formation successfully demonstrates the validity of the proposed fabrication protocol and represents an important step toward the use of a milling technique for PDMS-based microfabrication.
Abstract: We provide a facile and low-cost method (F-L) to fabricate a two-dimensional positive master using a milling technique for polydimethylsiloxane (PDMS)-based microchannel molding. This method comprises the following steps: (1) a positive microscale master of the geometry is milled on to an acrylic block; (2) pre-cured PDMS is used to mold the microscale positive master; (3) the PDMS plate is peeled off from the master and punctured with a blunt needle; and (4) the PDMS plate is O₂ plasma bonded to a glass slide. Using this technique, we can fabricate microchannels with very simple protocols quickly and inexpensively. This method also avoids breakage of the end mill (ϕ = 0.4 mm) of the computerized numerical control (CNC) system when fabricating the narrow channels (width < 50 µm). The prominent surface roughness of the milled bottom-layer could be overcomed by pre-cured PDMS with size trade-off in design. Finally, emulsion formation successfully demonstrates the validity of the proposed fabrication protocol. This work represents an important step toward the use of a milling technique for PDMS-based microfabrication.
19 citations
TL;DR: This paper describes a flexible and rapid prototyping technique for microfluidics by introducing a high-performance/cost-ratio laser to the traditional soft lithography, suitable for master fabrication.
Abstract: In microfluidic device prototyping, master fabrication by traditional photolithography is expensive and time-consuming, especially when the design requires being repeatedly modified to achieve a satisfactory performance. By introducing a high-performance/cost-ratio laser to the traditional soft lithography, this paper describes a flexible and rapid prototyping technique for microfluidics. An ultraviolet (UV) laser directly writes on the photoresist without a photomask, which is suitable for master fabrication. By eliminating the constraints of fixed patterns in the traditional photomask when the masters are made, this prototyping technique gives designers/researchers the convenience to revise or modify their designs iteratively. A device fabricated by this method is tested for particle separation and demonstrates good properties. This technique provides a flexible and rapid solution to fabricating microfluidic devices for non-professionals at relatively low cost.
11 citations
Cites background from "Blood Flow Visualization and Measur..."
...Micromilling [45] 30 μm 4 h Micromilling machine Semicircular channel, durable master High-cost initialization and easily tool breakage...
[...]
TL;DR: Numerical simulations have revolutionized research in several engineering areas by contributing to the understanding and improvement of several processes, being biomedical engineering one of them as mentioned in this paper, and significant advances have been made in this field of research.
Abstract: Numerical simulations have revolutionized research in several engineering areas by contributing to the understanding and improvement of several processes, being biomedical engineering one of them. Due to their potential, computational tools have gained visibility and have been increasingly used by several research groups as a supporting tool for the development of preclinical platforms as they allow studying, in a more detailed and faster way, phenomena that are difficult to study experimentally due to the complexity of biological processes present in these models-namely, heat transfer, shear stresses, diffusion processes, velocity fields, etc. There are several contributions already in the literature, and significant advances have been made in this field of research. This review provides the most recent progress in numerical studies on advanced microfluidic devices, such as organ-on-a-chip (OoC) devices, and how these studies can be helpful in enhancing our insight into the physical processes involved and in developing more effective OoC platforms. In general, it has been noticed that in some cases, the numerical studies performed have limitations that need to be improved, and in the majority of the studies, it is extremely difficult to replicate the data due to the lack of detail around the simulations carried out.
9 citations
References
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01 Jan 2004
TL;DR: ImageJ is an open source Java-written program that is used for many imaging applications, including those that that span the gamut from skin analysis to neuroscience, and can read most of the widely used and significant formats used in biomedical images.
Abstract: Wayne Rasband of NIH has created ImageJ, an open source Java-written program that is now at version 1.31 and is used for many imaging applications, including those that that span the gamut from skin analysis to neuroscience. ImageJ is in the public domain and runs on any operating system (OS). ImageJ is easy to use and can do many imaging manipulations. A very large and knowledgeable group makes up the user community for ImageJ. Topics covered are imaging abilities; cross platform; image formats support as of June 2004; extensions, including macros and plug-ins; and imaging library. NIH reports tens of thousands of downloads at a rate of about 24,000 per month currently. ImageJ can read most of the widely used and significant formats used in biomedical images. Manipulations supported are read/write of image files and operations on separate pixels, image regions, entire images, and volumes (stacks in ImageJ). Basic operations supported include convolution, edge detection, Fourier transform, histogram and particle analyses, editing and color manipulation, and more advanced operations, as well as visualization. For assistance in using ImageJ, users e-mail each other, and the user base is highly knowledgeable and will answer requests on the mailing list. A thorough manual with many examples and illustrations has been written by Tony Collins of the Wright Cell Imaging Facility at Toronto Western Research Institute and is available, along with other listed resources, via the Web.
12,060 citations
"Blood Flow Visualization and Measur..." refers methods in this paper
...Then, all videos were evaluated using a manual image analysis by using the plugin MtrackJ [23, 24], from the software ImageJ (NIH) [25]....
[...]
TL;DR: In this article, a cutting plotter with an addressable resolution of 10 /spl mu/m was used to cut microstructures in various films with thicknesses ranging from 25 to 1000 /spl µ/m.
Abstract: This paper introduces xurography, or "razor writing," as a novel rapid prototyping technique for creating microstructures in various films. This technique uses a cutting plotter traditionally used in the sign industry for cutting graphics in adhesive vinyl films. A cutting plotter with an addressable resolution of 10 /spl mu/m was used to cut microstructures in various films with thicknesses ranging from 25 to 1000 /spl mu/m. Positive features down to 35 /spl mu/m and negative features down to 18 /spl mu/m were cut in a 25 /spl mu/m thick material. Higher aspect ratios of 5.2 for positive features and 8 for negative features were possible in a 360 /spl mu/m thick material. A simple model correlating material properties to minimum feature size is introduced. Multilayered microstructures cut from pressure sensitive and thermal activated adhesive films were laminated in less than 30 min without photolithographic processes or chemicals. Potential applications of these microstructures are explored including: shadow masking, electroplating, micromolds for PDMS, and multilayered three-dimensional (3-D) channels. This inexpensive method can rapidly prototype microfluidic devices or tertiary fluid connections for higher resolution devices. [1488].
321 citations
"Blood Flow Visualization and Measur..." refers methods in this paper
...This method has shown to be an effective, novel, and rapid prototyping technique to fabricate microfluidic channels [11]....
[...]
TL;DR: The paper discusses the main ingredients of the commonly used tracking paradigm and subsequently reconsider its competence by comparing it to certain aspects of visual motion perception in human beings, keeping in mind the complexity and variability of biological image data.
Abstract: This paper aims to simulate the application of more advanced computer vision techniques to tracking in biological molecular imaging by surveying the literature and sketching the current state of affairs in the field for a signal and image processing audience. After describing the basic principles of visualizing molecular dynamics in living cells and giving some examples of biological molecular dynamics studies, the paper summarizes the problems and limitations intrinsic to imaging at this scale. The paper then discusses the main ingredients of the commonly used tracking paradigm and subsequently reconsider its competence by comparing it to certain aspects of visual motion perception in human beings, keeping in mind the complexity and variability of biological image data. Finally, it summarizes the main points of attention for future research and the challenges that lie ahead.
240 citations
"Blood Flow Visualization and Measur..." refers methods in this paper
...Then, all videos were evaluated using a manual image analysis by using the plugin MtrackJ [23, 24], from the software ImageJ (NIH) [25]....
[...]
TL;DR: In this review, a selection of the most recent lithographic and non-lithographic low-cost techniques to fabricate microfluidic structures, focused on the features and limitations of each technique.
235 citations
Journal Article•
TL;DR: Using an in vitro model, it is shown experimentally that for a fixed flow rate a geometrical constriction in the flow can artificially enhance the cell-free layer and proposed a microfluidic application of this focusing effect for separation of the red blood cells from the suspending plasma.
225 citations