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1
Grimmer, Andreas, Philipp Frank, Philipp Ebner, Sebastian Häfner, Andreas Richter, and Robert Wille. "Meander Designer: Automatically Generating Meander Channel Designs." Micromachines 9, no. 12 (November 27, 2018): 625. http://dx.doi.org/10.3390/mi9120625.
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Microfluidics continues to bring innovation to the life sciences. It stimulates progress by enabling new ways of research in biology, chemistry, and biotechnology. However, when designing a microfluidic device, designers have to conduct many tasks by hand—resulting in labor-intensive processes. In particular, when drawing the design of the device, designers have to handle re-occurring entities. Meander channels are one example, which are frequently used in different platforms but always have to fit the respective application and design rules. This work presents an online tool which is capable of automatically generating user-defined, two-dimensional designs of fluidic meander channels facilitating fluidic hydrodynamic resistances. The tool implements specific design rules as it considers the user’s needs and fabrication requirements. The compliance of the meanders generated by the proposed tool is confirmed by fabricating the generated designs and comparing whether the resulting devices indeed realize the desired specification. To this end, two case studies are considered: first, the realization of dedicated fluidic resistances and, second, the realization of dedicated mixing ratios of fluids. The results demonstrate the versatility of the tool regarding application and technology. Overall, the freely accessible tool with its flexibility and simplicity renders manual drawing of meanders obsolete and, hence, allows for a faster, more straightforward design process.
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Wu, J. W., H. M. Xia, Y. Y. Zhang, and P. Zhu. "Microfluidic mixing through oscillatory transverse perturbations." Modern Physics Letters B 32, no. 12n13 (May 10, 2018): 1840030. http://dx.doi.org/10.1142/s0217984918400304.
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Fluid mixing in miniaturized fluidic devices is a challenging task. In this work, the mixing enhancement through oscillatory transverse perturbations coupling with divergent circular chambers is studied. To simplify the design, an autonomous microfluidic oscillator is used to produce the oscillatory flow. It is then applied to four side-channels that intersect with a central channel of constant flow. The mixing performance is tested at high fluid viscosities of up to 16 cP. Results show that the oscillatory flow can cause strong transverse perturbations which effectively enhance the mixing. The influence of a fluidic capacitor in the central channel is also examined, which at low viscosities can intensify the perturbations and further improve the mixing.
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Su, Liang Yao, Yue Yang, and Zhong Bin Xu. "Numerical Simulation of Micromixing with Isolate Bubbles in Microfluidic Flow-Focusing Devices." Advanced Materials Research 781-784 (September 2013): 2876–80. http://dx.doi.org/10.4028/www.scientific.net/amr.781-784.2876.
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Microbubbles play an important role in the micromixing of micro-fluidic systems. However, there are few results in the literature about the mixing of the liquids caused by bubbles flow. The paper presents the numerical simulation of bubbles flow in microfluidic, which agrees well with the experimental results. The influence of velocity amplitude, frequency and phase difference on the mixing performance was investigated. The results show that the isolate bubbles as obstruction can improve mixing efficiency in the true straight microchannel, the bigger the velocity amplitude, and the higher the frequency, the better the mixing efficiency is, but the mixing efficiency has nothing to do with the number of bubbles and just benefit from the certain phase difference. With the other two parameter remains unchanged, the mixing performance achieves the best value when the velocity amplitude is 0.25m/s, the frequency is 25HZ, the phase difference is 0.25, respectively. The study referring to bubbles flow induced mixing performance is very important for many microfluidic devices.
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Boutiette, Amber L., Cristoffer Toothaker, Bailey Corless, Chouaib Boukaftane, and Caitlin Howell. "3D printing direct to industrial roll-to-roll casting for fast prototyping of scalable microfluidic systems." PLOS ONE 15, no. 12 (December 28, 2020): e0244324. http://dx.doi.org/10.1371/journal.pone.0244324.
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Microfluidic technologies have enormous potential to offer breakthrough solutions across a wide range of applications. However, the rate of scale-up and commercialization of these technologies has lagged significantly behind promising breakthrough developments in the lab, due at least in part to the problems presented by transitioning from benchtop fabrication methods to mass-manufacturing. In this work, we develop and validate a method to create functional microfluidic prototype devices using 3D printed masters in an industrial-scale roll-to-roll continuous casting process. There were no significant difference in mixing performance between the roll-to-roll cast devices and the PDMS controls in fluidic mixing tests. Furthermore, the casting process provided information on the suitability of the prototype microfluidic patterns for scale-up. This work represents an important step in the realization of high-volume prototyping and manufacturing of microfluidic patterns for use across a broad range of applications.
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Yuen, Po Ki, Guangshan Li, Yijia Bao, and Uwe R. Müller. "Microfluidic devices for fluidic circulation and mixing improve hybridization signal intensity on DNA arrays." Lab Chip 3, no. 1 (2003): 46–50. http://dx.doi.org/10.1039/b210274a.
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Yao, Ping, Ronghui Wang, Xinge Xi, Yanbin Li, and Steve Tung. "3D-Printed Pneumatic Microfluidic Mixer for Colorimetric Detection of Listeria monocytogenes." Transactions of the ASABE 62, no. 3 (2019): 841–50. http://dx.doi.org/10.13031/trans.13245.
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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.
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Wang, Anyang, Domin Koh, Philip Schneider, Evan Breloff, and Kwang W. Oh. "A Compact, Syringe-Assisted, Vacuum-Driven Micropumping Device." Micromachines 10, no. 8 (August 17, 2019): 543. http://dx.doi.org/10.3390/mi10080543.
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In this paper, a simple syringe‑assisted pumping method is introduced. The proposed fluidic micropumping system can be used instead of a conventional pumping system which tends to be large, bulky, and expensive. The micropump was designed separately from the microfluidic channels and directly bonded to the outlet of the microfluidic device. The pump components were composed of a dead‑end channel which was surrounded by a microchamber. A syringe was then connected to the pump structure by a short tube, and the syringe plunger was manually pulled out to generate low pressure inside the microchamber. Once the sample was loaded in the inlet, air inside the channel diffused into the microchamber through the PDMS (polydimethylsiloxane) wall, acting as a dragging force and pulling the sample toward the outlet. A constant flow with a rate that ranged from 0.8 nl · s − 1 to 7.5 nl · s − 1 was achieved as a function of the geometry of the pump, i.e., the PDMS wall thickness and the diffusion area. As a proof-of-concept, microfluidic mixing was demonstrated without backflow. This method enables pumping for point-of-care testing (POCT) with greater flexibility in hand-held PDMS microfluidic devices.
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Zoupanou, Sofia, Maria Serena Chiriacò, Iolena Tarantini, and Francesco Ferrara. "Innovative 3D Microfluidic Tools for On-Chip Fluids and Particles Manipulation: From Design to Experimental Validation." Micromachines 12, no. 2 (January 21, 2021): 104. http://dx.doi.org/10.3390/mi12020104.
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Micromixers are essential components in lab-on-a-chip devices, of which the low efficiency can limit many bio-application studies. Effective mixing with automation capabilities is still a crucial requirement. In this paper, we present a method to fabricate a three-dimensional (3D) poly(methyl methacrylate) (PMMA) fluidic mixer by combining computer-aided design (CAD), micromilling technology, and experimental application via manipulating fluids and nanoparticles. The entire platform consists of three microfabricated layers with a bottom reservoir-shaped microchannel, a central serpentine channel, and a through-hole for interconnection and an upper layer containing inlets and outlet. The sealing process of the three layers and the high-precision and customizable methods used for fabrication ensure the realization of the monolithic 3D architecture. This provides buried running channels able to perform passive chaotic mixing and dilution functions, thanks to a portion of the pathway in common between the reservoir and serpentine layers. The possibility to plug-and-play micropumping systems allows us to easily demonstrate the feasibility and working features of our device for tracking the mixing and dilution performances of the micromixer by using colored fluids and fluorescent nanoparticles as the proof of concept. Exploiting the good transparency of the PMMA, spatial liquid composition and better control over reaction variables are possible, and the real-time monitoring of experiments under a fluorescence microscope is also allowed. The tools shown in this paper are easily integrable in more complex lab-on-chip platforms.
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Mukherjee, Siddhartha, Jayabrata Dhar, Sunando DasGupta, and Suman Chakraborty. "Patterned surface charges coupled with thermal gradients may create giant augmentations of solute dispersion in electro-osmosis of viscoelastic fluids." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, no. 2221 (January 2019): 20180522. http://dx.doi.org/10.1098/rspa.2018.0522.
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Augmenting the dispersion of a solute species and fluidic mixing remains a challenging proposition in electrically actuated microfluidic devices, primarily due to an inherent plug-like nature of the velocity profile under uniform surface charge conditions. While a judicious patterning of surface charges may obviate some of the concerning challenges, the consequent improvement in solute dispersion may turn out to be marginal. Here, we show that by exploiting a unique coupling of patterned surface charges with intrinsically induced thermal gradients, it may be possible to realize giant augmentations in solute dispersion in electro-osmotic flows. This is effectively mediated by the phenomena of Joule heating and surface heat dissipation, so as to induce local variations in electrical properties. Combined with the rheological premises of a viscoelastic fluid that are typically reminiscent of common biofluids handled in lab-on-a-chip-based micro-devices, our results demonstrate that the consequent electro-hydrodynamic forcing may open up favourable windows for augmented hydrodynamic dispersion, which has not yet been unveiled.
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Zhang, Peiran, Hunter Bachman, Adem Ozcelik, and Tony Jun Huang. "Acoustic Microfluidics." Annual Review of Analytical Chemistry 13, no. 1 (June 12, 2020): 17–43. http://dx.doi.org/10.1146/annurev-anchem-090919-102205.
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Acoustic microfluidic devices are powerful tools that use sound waves to manipulate micro- or nanoscale objects or fluids in analytical chemistry and biomedicine. Their simple device designs, biocompatible and contactless operation, and label-free nature are all characteristics that make acoustic microfluidic devices ideal platforms for fundamental research, diagnostics, and therapeutics. Herein, we summarize the physical principles underlying acoustic microfluidics and review their applications, with particular emphasis on the manipulation of macromolecules, cells, particles, model organisms, and fluidic flows. We also present future goals of this technology in analytical chemistry and biomedical research, as well as challenges and opportunities.
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Nielsen, Anna V., Michael J. Beauchamp, Gregory P. Nordin, and Adam T. Woolley. "3D Printed Microfluidics." Annual Review of Analytical Chemistry 13, no. 1 (June 12, 2020): 45–65. http://dx.doi.org/10.1146/annurev-anchem-091619-102649.
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Traditional microfabrication techniques suffer from several disadvantages, including the inability to create truly three-dimensional (3D) architectures, expensive and time-consuming processes when changing device designs, and difficulty in transitioning from prototyping fabrication to bulk manufacturing. 3D printing is an emerging technique that could overcome these disadvantages. While most 3D printed fluidic devices and features to date have been on the millifluidic size scale, some truly microfluidic devices have been shown. Currently, stereolithography is the most promising approach for routine creation of microfluidic structures, but several approaches under development also have potential. Microfluidic 3D printing is still in an early stage, similar to where polydimethylsiloxane was two decades ago. With additional work to advance printer hardware and software control, expand and improve resin and printing material selections, and realize additional applications for 3D printed devices, we foresee 3D printing becoming the dominant microfluidic fabrication method.
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Jia, Xiaoyu, Bingchen Che, Guangyin Jing, and Ce Zhang. "Air-Bubble Induced Mixing: A Fluidic Mixer Chip." Micromachines 11, no. 2 (February 14, 2020): 195. http://dx.doi.org/10.3390/mi11020195.
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In this study, we report the design and fabrication of a novel fluidic mixer. As proof-of-concept, the laminar flow in the main channel is firstly filled with small air-bubbles, which act as active stirrers inducing chaotic convective turbulent flow, and thus enhance the solutes mixing even at a low input flow rate. To further increase mixing efficiency, a design of neck constriction is included, which changes the relative positions of the inclusion bubbles significantly. The redistribution of liquid volume among bubbles then causes complex flow profile, which further enhances mixing. This work demonstrates a unique approach of utilizing air bubbles to facilitate mixing in bulk solution, which can find the potential applications in microfluidics, fast medical analysis, and biochemical synthesis.
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Ahmadi, Fatemeh, Kenza Samlali, Philippe Q. N. Vo, and Steve C. C. Shih. "An integrated droplet-digital microfluidic system for on-demand droplet creation, mixing, incubation, and sorting." Lab on a Chip 19, no. 3 (2019): 524–35. http://dx.doi.org/10.1039/c8lc01170b.
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A new microfluidic platform that integrates droplet and digital microfluidics to automate a variety of fluidic operations. The platform was applied to culturing and to selecting yeast mutant cells in ionic liquid.
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Pal, Debashis, and Suman Chakraborty. "New regimes of dispersion in microfluidics as mediated by travelling temperature waves." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, no. 2230 (October 2019): 20190382. http://dx.doi.org/10.1098/rspa.2019.0382.
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We unveil new regimes of dispersion in miniaturized fluidic devices, by considering fluid flow triggered by a travelling temperature wave. When a temperature wave travels along a channel wall, it alters the density and viscosity of the adjacent fluid periodically. Successive expansion–contraction of the fluid volume through a spatio-temporally evolving viscosity field generates a net fluidic current. Based on the temporal evolution of the axial dispersion coefficient, new regimes of dispersion—such as a short-time ‘oscillating regime’ and a large-time ‘stable regime’—have been identified, which are absent in traditionally addressed flows through miniaturized fluidic devices. Our analysis reveals that the oscillation of axial dispersion persists until the variance of species concentration becomes equal to half of the square of the wavelength of the thermal wave. The time period of oscillation in the dispersion coefficient turns out to be a unique function of the thermal wavelength and net flow velocity induced by thermoviscous pumping. The results of this study are likely to contribute towards the improvement of microscale systems that are subjected to periodic temperature variations, including microreactors and DNA amplification devices.
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Adamovic, Nadja, Ioanna Giouroudi, Jovan Matovic, Zoran Djinovic, and Ulrich Schmid. "Microactuators for Fluidic Applications: Principles, Devices, and Systems." Journal of Microelectronics and Electronic Packaging 6, no. 4 (October 1, 2009): 250–64. http://dx.doi.org/10.4071/1551-4897-6.4.250.
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Much effort in microfluidics research has been aimed at designing microscale pumps, valves, switches, dispensers, mixers, filters, separators, and so on, which have a major role in the development of innovative systems like chemical process control, bioanalytical devices, medical drug delivery systems, environmental control, and others. Most of these microfluidic devices have one thing in common: the need for precise manipulation and control of small amounts of fluids. MEMS/NEMS research is continuously opening up new knowledge on modeling approaches, novel materials, and MEMS/NEMS processing technologies that stimulate and accelerate the development of new actuation principles and novel actuator configurations. This review paper presents research work on different actuation techniques that are used for the whole range of microfluidic applications. It covers thermomechanical and electrochemical actuation principles, as well as actuation induced with external electric or magnetic fields. It presents a brief explanation of the operating principle of each type of actuator, actuator configuration, its main characteristics, like power consumption, operational voltage, frequency range, and working fluids, and a discussion of comparisons among different actuation schemes. This study compiles and provides some basic guidelines for selection of the actuation schemes that are currently implemented in microfluidic devices.
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Hejazian, Majid, Eugeniu Balaur, and Brian Abbey. "A Numerical Study of Sub-Millisecond Integrated Mix-and-Inject Microfluidic Devices for Sample Delivery at Synchrotron and XFELs." Applied Sciences 11, no. 8 (April 10, 2021): 3404. http://dx.doi.org/10.3390/app11083404.
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Microfluidic devices which integrate both rapid mixing and liquid jetting for sample delivery are an emerging solution for studying molecular dynamics via X-ray diffraction. Here we use finite element modelling to investigate the efficiency and time-resolution achievable using microfluidic mixers within the parameter range required for producing stable liquid jets. Three-dimensional simulations, validated by experimental data, are used to determine the velocity and concentration distribution within these devices. The results show that by adopting a serpentine geometry, it is possible to induce chaotic mixing, which effectively reduces the time required to achieve a homogeneous mixture for sample delivery. Further, we investigate the effect of flow rate and the mixer microchannel size on the mixing efficiency and minimum time required for complete mixing of the two solutions whilst maintaining a stable jet. In general, we find that the smaller the cross-sectional area of the mixer microchannel, the shorter the time needed to achieve homogeneous mixing for a given flow rate. The results of these simulations will form the basis for optimised designs enabling the study of molecular dynamics occurring on millisecond timescales using integrated mix-and-inject microfluidic devices.
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Lafleur, Josiane P., Detlef Snakenborg, Søren S. Nielsen, Magda Møller, Katrine N. Toft, Andreas Menzel, Jes K. Jacobsen, Bente Vestergaard, Lise Arleth, and Jörg P. Kutter. "Automated microfluidic sample-preparation platform for high-throughput structural investigation of proteins by small-angle X-ray scattering." Journal of Applied Crystallography 44, no. 5 (August 18, 2011): 1090–99. http://dx.doi.org/10.1107/s0021889811030068.
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A new microfluidic sample-preparation system is presented for the structural investigation of proteins using small-angle X-ray scattering (SAXS) at synchrotrons. The system includes hardware and software features for precise fluidic control, sample mixing by diffusion, automated X-ray exposure control, UV absorbance measurements and automated data analysis. As little as 15 µl of sample is required to perform a complete analysis cycle, including sample mixing, SAXS measurement, continuous UV absorbance measurements, and cleaning of the channels and X-ray cell with buffer. The complete analysis cycle can be performed in less than 3 min. Bovine serum albumin was used as a model protein to characterize the mixing efficiency and sample consumption of the system. The N2 fragment of an adaptor protein (p120-RasGAP) was used to demonstrate how the device can be used to survey the structural space of a protein by screening a wide set of conditions using high-throughput techniques.
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Huang, Q., B. Jones, and N. J. Leighton. "Hybrid Solid State Fluidic Technique in Engine Fuel Injection Systems." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 207, no. 1 (January 1993): 35–41. http://dx.doi.org/10.1243/pime_proc_1993_207_157_02.
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This paper describes a multi-point fuel injection system utilizing fiuidic devices as fuel injector stages for spark ignition engines. The novel fuel injector unit consists of no-moving-part fluidic devices controlled by a solenoid valve interface and unique air/fuel mixing nozzles for good fuel atomization. The results of laboratory tests show that the fluidic device stage has a fast dynamic response and its on/off switching delay to the control flow signal is within 1 ms. A balanced fuel distribution at the four fluidic injector stages (for a four-cylinder engine) and well-atomized air/fuel mixture at the mixing nozzles were obtained from this injection system. The engine tests show that this fuel injection system provides an extended lean limit of the air/fuel mixture, 7 per cent improvement in fuel economy and 10 per cent reduction in hydrocarbon (HC) emissions compared with a base-line carburetted fuelling system due to the improved fuel distribution and air/fuel mixing quality by the multi-point fluidic injection system.
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Shih, Chih Hsin, Chien Hsing Lu, Chia Hui Lin, and Hou Jin Wu. "Design and Analysis of Micromixers on a Centrifugal Platform." Advanced Materials Research 74 (June 2009): 203–6. http://dx.doi.org/10.4028/www.scientific.net/amr.74.203.
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This work reports a novel mixing design that can do fast, batch-typed liquid mixing on a centrifugal platform. Mixing is an important procedure for many applications related to chemical reactors and biological assays, especially in the field of microfluidics. The extremely small sizes of microchannels make it difficult to achieve turbulence to assist mixing. To overcome this problem, a meandering fluidic design on the centrifugal platform is proposed. Centrifual force promotes mixing by inducing lateral flow movement in the circular section and flow focusing effect in the bending section. The degree of mixing was studied for solutions with various viscosities under different rotational speeds. The experimental results showed that this mixer can mix microliter or nanoliter volumes of aqueous solutions within one second.
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Hassan, Sammer-ul, Aamira Tariq, Zobia Noreen, Ahmed Donia, Syed Z. J. Zaidi, Habib Bokhari, and Xunli Zhang. "Capillary-Driven Flow Microfluidics Combined with Smartphone Detection: An Emerging Tool for Point-of-Care Diagnostics." Diagnostics 10, no. 8 (July 22, 2020): 509. http://dx.doi.org/10.3390/diagnostics10080509.
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Point-of-care (POC) or near-patient testing allows clinicians to accurately achieve real-time diagnostic results performed at or near to the patient site. The outlook of POC devices is to provide quicker analyses that can lead to well-informed clinical decisions and hence improve the health of patients at the point-of-need. Microfluidics plays an important role in the development of POC devices. However, requirements of handling expertise, pumping systems and complex fluidic controls make the technology unaffordable to the current healthcare systems in the world. In recent years, capillary-driven flow microfluidics has emerged as an attractive microfluidic-based technology to overcome these limitations by offering robust, cost-effective and simple-to-operate devices. The internal wall of the microchannels can be pre-coated with reagents, and by merely dipping the device into the patient sample, the sample can be loaded into the microchannel driven by capillary forces and can be detected via handheld or smartphone-based detectors. The capabilities of capillary-driven flow devices have not been fully exploited in developing POC diagnostics, especially for antimicrobial resistance studies in clinical settings. The purpose of this review is to open up this field of microfluidics to the ever-expanding microfluidic-based scientific community.
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Raman, G., S. Packiarajan, G. Papadopoulos, C. Weissman, and S. Raghu. "Jet thrust vectoring using a miniature fluidic oscillator." Aeronautical Journal 109, no. 1093 (March 2005): 129–38. http://dx.doi.org/10.1017/s0001924000000634.
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Abstract This paper presents a new approach to vectoring jet thrust using a miniature fluidic actuator that provided spatially distributed mass addition. The fluidic actuators used had no moving parts and produced oscillatory flow with a square wave form at frequencies up to 1·6kHz. A subsonic jet with an exit diameter of 3·81cm was controlled using single and dual fluidic actuators, each with an equivalent circular diameter of 1·06mm. The fluidic nozzle was operated at pressures between 20·68 and 165·47kPa. The objectives of the present work included documentation of the actuation characteristics of fluidic devices, assessment of the effectiveness of fluidic devices for jet thrust vectoring, and evaluation of mass flow requirements for vectoring under various conditions. Measurements were made in the flow field using a pitot probe for the vectored and unvectored cases. Some acoustic measurements were made using microphones in the near-field and for selected cases particle image velocimetry (PIV) measurements were made. Thrust vectoring was obtained in low speed jets by momentum effects with fluidic device mass flow rates of only 2 × 10–4kg/sec (0·6% of main jet mass flow per fluidic oscillator). Although a single fluidic device produced vectoring of the primary jet, the dual fluidic device configuration (with two fluidic devices on either side of the jet exit) produced mass flux enhancement of 28% with no vectoring. Our results indicate that fluidic actuators have the potential for use in thrust vectoring, flow mixing and industrial flow deflection applications.
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Green, James, Arne Holdø, and Aman Khan. "A review of passive and active mixing systems in microfluidic devices." International Journal of Multiphysics 1, no. 1 (January 2007): 1–32. http://dx.doi.org/10.1260/175095407780130544.
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Kim, Byoung Jae, Sang Youl Yoon, Kyung Heon Lee, and Hyung Jin Sung. "Development of a microfluidic device for simultaneous mixing and pumping." Experiments in Fluids 46, no. 1 (August 20, 2008): 85–95. http://dx.doi.org/10.1007/s00348-008-0541-1.
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WEIß, DENNIS, ANDREAS GREINER, JAN LIENEMANN, and JAN G. KORVINK. "SPH BASED OPTIMIZATION OF ELECTROWETTING-DRIVEN DIGITAL MICROFLUIDICS WITH ADVANCED ACTUATION PATTERNS." International Journal of Modern Physics C 24, no. 12 (November 13, 2013): 1340012. http://dx.doi.org/10.1142/s0129183113400123.
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Fast and thorough mixing is a crucial operation of digital microfluidic devices, where discrete and small fluid portions are moved and processed. In this paper, we want to analyze and to optimize the mixing process by substituting conventional motion and superposing oscillatory and translational modes. An accurate multiphase smoothed particle hydrodynamics (SPH) discretization for incompressible flow is instantiated. Different harmonic excitation patterns for the solid–liquid surface energy are applied and their influence on droplet mode shapes, formation of eddies and the Shannon entropy of droplet fluid components are measured. We tailor enhanced actuation patterns which improve mixing grade and reduce mixing time.
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Paoli, Roberto, Davide Di Giuseppe, Maider Badiola-Mateos, Eugenio Martinelli, Maria Jose Lopez-Martinez, and Josep Samitier. "Rapid Manufacturing of Multilayered Microfluidic Devices for Organ on a Chip Applications." Sensors 21, no. 4 (February 16, 2021): 1382. http://dx.doi.org/10.3390/s21041382.
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Microfabrication and Polydimethylsiloxane (PDMS) soft-lithography techniques became popular for microfluidic prototyping at the lab, but even after protocol optimization, fabrication is yet a long, laborious process and partly user-dependent. Furthermore, the time and money required for the master fabrication process, necessary at any design upgrade, is still elevated. Digital Manufacturing (DM) and Rapid-Prototyping (RP) for microfluidics applications arise as a solution to this and other limitations of photo and soft-lithography fabrication techniques. Particularly for this paper, we will focus on the use of subtractive DM techniques for Organ-on-a-Chip (OoC) applications. Main available thermoplastics for microfluidics are suggested as material choices for device fabrication. The aim of this review is to explore DM and RP technologies for fabrication of an OoC with an embedded membrane after the evaluation of the main limitations of PDMS soft-lithography strategy. Different material options are also reviewed, as well as various bonding strategies. Finally, a new functional OoC device is showed, defining protocols for its fabrication in Cyclic Olefin Polymer (COP) using two different RP technologies. Different cells are seeded in both sides of the membrane as a proof of concept to test the optical and fluidic properties of the device.
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Huang, Q., and D. P. Sansum. "An Experimental Study of a Fluidic Type Fuel Injector in Comparison With a Solenoid Type Injector." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 210, no. 2 (April 1996): 131–47. http://dx.doi.org/10.1243/pime_proc_1996_210_254_02.
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An experimental study of a fluidic type fuel injector for spark ignition (SI) engines is described in this paper. The fluidic injector unit consists of four monostable fluidic devices controlled by a solenoid interface and air–fuel mixing nozzles for better fuel atomization. The prototype fluidic injector unit was implemented on a research engine. The results of air–fuel ratio (AFR) variations, engine combustion characteristics and exhaust emissions from the fluidic injector were compared with those from a baseline solenoid type injector. It was demonstrated from single cylinder engine tests that the fluidic system produces 9 to 20 per cent lower hydrocarbon (HC) emissions and 5 to 8 per cent higher indicated mean effective pressure (IMEP) than the baseline injection system. This has confirmed the effectiveness of the use of air-assisted fluidic injectors and the fact that improved mixture preparation and better fuel presentation are obtained by the fluidic injector. However, the lean misfire limit by the fluidic injector is reduced by 1 AFR compared to that of the solenoid injector due to large AFR dispersions caused by cyclic fuel delivery variations of the fluidic device. It is envisaged that the fluidic injector potentially offers cost and emission benefits for SI engines when the cyclic flow stability is improved.
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Sharma, Smriti, and Vinayak Bhatia. "Magnetic nanoparticles in microfluidics-based diagnostics: an appraisal." Nanomedicine 16, no. 15 (June 2021): 1329–42. http://dx.doi.org/10.2217/nnm-2021-0007.
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The use of magnetic nanoparticles (MNPs) in microfluidics based diagnostics is a classic case of micro-, nano- and bio-technology coming together to design extremely controllable, reproducible, and scalable nano and micro ‘ on-chip bio sensing systems.’ In this review, applications of MNPs in microfluidics ranging from molecular diagnostics and immunodiagnostics to clinical uses have been examined. In addition, microfluidic mixing and capture of analytes using MNPs, and MNPs as carriers in microfluidic devices has been investigated. Finally, the challenges and future directions of this upcoming field have been summarized. The use of MNP-based microfluidic devices, will help in developing decentralized or ‘ point of care’ testing globally, contributing to affordable healthcare, particularly, for middle- and low-income developing countries.
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Whitlow, Harry J., Li Ping Wang, and Leona Gilbert. "Transport of Water and Particles in Microfluidics Devices Lithographically Fabricated Using Proton Beam Writing (PBW)." Advanced Materials Research 74 (June 2009): 129–32. http://dx.doi.org/10.4028/www.scientific.net/amr.74.129.
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Proton beam writing (PBW) is a MeV ion beam lithography technique that has gained interest in many biological applications such as fabricating microfluidic devices for Lab-On-a-Chip (LOC) applications where capillary forces are important for fluid flow. PBW has a unique capability of being able to direct-write patterns in thick (1-30µm) polymer resist layers with straight vertical sidewalls. It can be used to prepare master stamps and moulds for mass production in polymeric materials. A recent development, where the direct writing of an entire pattern element is carried out in parallel makes PBW especially well suited for Bio-MEMS LOC applications. In this study we have examined the flow dynamics using video microscopy of deionised water in fluidic channel patterns fluid reservoirs, capillary sections and a capillary pump written by PBW. The video microscopy data also demonstrated that the wetting behavior of the surface strongly influences the dynamics of fluid flow. This makes new approaches for LOC fabrication feasible and powerful.
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Balaji, Vidhya, Kurt Castro, and Albert Folch. "A Laser-Engraving Technique for Portable Micropneumatic Oscillators." Micromachines 9, no. 9 (August 24, 2018): 426. http://dx.doi.org/10.3390/mi9090426.
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Microfluidic automation technology is at a stage where the complexity and cost of external hardware control often impose severe limitations on the size and functionality of microfluidic systems. Developments in autonomous microfluidics are intended to eliminate off-chip controls to enable scalable systems. Timing is a fundamental component of the digital logic required to manipulate fluidic flow. The authors present a self-driven pneumatic ring oscillator manufactured by assembling an elastomeric sheet of polydimethylsiloxane (PDMS) between two laser-engraved polymethylmethacrylate (PMMA) layers via surface activation through treatment with 3-aminopropyltriethoxysilane (APTES). The frequency of the fabricated oscillators is in the range of 3–7.5 Hz with a maximum of 14 min constant frequency syringe-powered operation. The control of a fluidic channel with the oscillator stages is demonstrated. The fabrication process represents an improvement in manufacturability compared to previous molding or etching approaches, and the resulting devices are inexpensive and portable, making the technology potentially applicable for wider use.
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Dhayal, Marshal, Chealho So, Jeong Sik Choi, and Jin Jun. "Control of Bio-MEMS Surface Chemical Properties in Micro Fluidic Devices for Biological Applications." Journal of Nanoscience and Nanotechnology 6, no. 11 (November 1, 2006): 3494–98. http://dx.doi.org/10.1166/jnn.2006.17968.
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Surface chemistry of silicon/glass based bio-MEMS was controlled by depositing plasma polymerized acrylic acid (ppAc) films at two different electrode positions in a two-stage plasma reactor. AFM and XPS were used to characterize the surface roughness and surface chemistry of the films, respectively. The surface of bio-MEMS was highly functionalized with carboxylic/ester functionalities with a very good surface uniformity. The proportion of carbon atoms as C–OX, C(=O)OX functionalities was decreased and an increase in C=O functionalities was observed when the electrode position was increased from the mesh. These functionalized bio-MEMS devices have advantages in fabrication of reusable micro fluidic devices and the variation of fluid velocity by changing the surface properties may be used to develop a micro-mixing system to control the mixing ratio of different fluids for different biological and chemical applications.
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Box, Finn, Gunnar G. Peng, Draga Pihler-Puzović, and Anne Juel. "Flow-induced choking of a compliant Hele-Shaw cell." Proceedings of the National Academy of Sciences 117, no. 48 (November 16, 2020): 30228–33. http://dx.doi.org/10.1073/pnas.2008273117.
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After centuries of striving for structural rigidity, engineers and scientists alike are increasingly looking to harness the deformation, buckling, and failure of soft materials for functionality. In fluidic devices, soft deformable components that respond to the flow have the advantage of being passive; they do not require external actuation. Harnessing flow-induced deformation for passive functionality provides a means of developing flow analogs of electronic circuit components such as fluidic diodes and capacitors. The electronic component that has so far been overlooked in the microfluidics literature—the fuse—is a passive safety device that relies on a controlled failure mechanism (melting) to protect a circuit from overcurrent. Here, we describe how a compliant Hele-Shaw cell behaves in a manner analogous to the electrical fuse; above a critical flux, the flow-induced deformation of the cell blocks the outflow, interrupting (choking) the flow. In particular, the pressure distribution within the fluid applies a spatially variant normal force to the soft boundary, which causes nonuniform deformation. As a consequence of lateral confinement and incompressibility of the soft material, this flow-induced elastic deformation manifests as bulging near the cell outflow; bulges that come into contact with the rigid cell roof interrupt the flow. We identify two nondimensional parameters that govern the central deflection and the choking of the cell, respectively. This study therefore provides the mechanical foundations for engineering passive-flow limiters into fluidic devices.
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Hahn, Jaeseung, and William M. Shih. "Thermal cycling of DNA devices via associative strand displacement." Nucleic Acids Research 47, no. 20 (October 4, 2019): 10968–75. http://dx.doi.org/10.1093/nar/gkz844.
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Abstract DNA-based devices often operate through a series of toehold-mediated strand-displacement reactions. To achieve cycling, fluidic mixing can be used to introduce ‘recovery’ strands to reset the system. However, such mixing can be cumbersome, non-robust, and wasteful of materials. Here we demonstrate mixing-free thermal cycling of DNA devices that operate through associative strand-displacement cascades. These cascades are favored at low temperatures due to the primacy of a net increase in base pairing, whereas rebinding of ‘recovery’ strands is favored at higher temperatures due to the primacy of a net release of strands. The temperature responses of the devices could be modulated by adjustment of design parameters such as the net increase of base pairs and the concentrations of strands. Degradation of function was not observable even after 500 thermal cycles. We experimentally demonstrated simple digital-logic circuits that evaluate at 35°C and reset after transient heating to 65°C. Thus associative strand displacement enables robust thermal cycling of DNA-based devices in a closed system.
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Bauer, Maria, Adrian Bahani, Tracy Ogata, and Marc Madou. "3D Printing of Elastic Membranes for Fluidic Pumping and Demonstration of Reciprocation Inserts on the Microfluidic Disc." Micromachines 10, no. 8 (August 19, 2019): 549. http://dx.doi.org/10.3390/mi10080549.
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While 3D printing is increasingly used in most fields of engineering, its utilization for microfluidics has thus far been limited. To demonstrate future applications of 3D printing for microfluidic structures, we investigate the fluidic characteristics of material jetted surfaces. We also demonstrate the manufacture of dual-material microfluidic inserts that feature rigid and elastic elements. The fabricated parts are inserted on a microfluidic CD, enhancing design freedom and prototyping capability of over molded parts. Furthermore, printed elastic membranes are tested for fatigue during elastic-pneumatic pumping and rigid and elastic surfaces are characterized with regards to hydrophilicity and surface topography. Finally, different printed disc inserts are demonstrated for moving liquid towards the center of rotation, the mixing of liquids, and controlling burst events through channels width.
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Abdi, Mohsen, Esmail Pishbin, Alireza Karimi, and Mahdi Navidbakhsh. "A Comparative Investigation on the Performance of Different Micro Mixers: Toward Cerebral Microvascular Analysis." Journal of Multiscale Modelling 08, no. 01 (February 22, 2017): 1650008. http://dx.doi.org/10.1142/s1756973716500086.
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In this study, a novel fluidic concept was presented to resemble the cerebral microvascular in four types to assess its complexity by using centrifugal platform. The setup consisted of a microstructured disk with a round mixing chamber rotating on a macroscopic drive unit. The left and right internal carotid arteries (L.ICA and R.ICA) and basilar artery (BA) are two isolated vascular system supplying circle of Willis (CoW). The left and right middle cerebral arteries (L.MCA and R.MCA), left and right anterior cerebral arteries (L.ACA and R.ACA), and finally left and right posterior cerebral arteries (L.PCA and R.PCA) constitute efferent arteries of CoW. In this study, cerebral microvascular was investigated by microfluidics approach. The results revealed that a more complex mixing chamber provides normal pixel percentage distribution with respect to the other ones. The outcomes of this study may have implications not only for perception of the intracranial vascular hemodynamic in healthy circumstance, but also for diagnosing the diseases in the blood circulatory system of the human body.
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Giraldo, Kevin A., Juan Sebastian Bermudez, Carlos E. Torres, Luis H. Reyes, Johann F. Osma, and Juan C. Cruz. "Microfluidics for Multiphase Mixing and Liposomal Encapsulation of Nanobioconjugates: Passive vs. Acoustic Systems." Fluids 6, no. 9 (August 31, 2021): 309. http://dx.doi.org/10.3390/fluids6090309.
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One of the main routes to ensure that biomolecules or bioactive agents remain active as they are incorporated into products with applications in different industries is by their encapsulation. Liposomes are attractive platforms for encapsulation due to their ease of synthesis and manipulation and the potential to fuse with cell membranes when they are intended for drug delivery applications. We propose encapsulating our recently developed cell-penetrating nanobioconjugates based on magnetite interfaced with translocating proteins and peptides with the purpose of potentiating their cell internalization capabilities even further. To prepare the encapsulates (also known as magnetoliposomes (MLPs)), we introduced a low-cost microfluidic device equipped with a serpentine microchannel to favor the interaction between the liposomes and the nanobioconjugates. The encapsulation performance of the device, operated either passively or in the presence of ultrasound, was evaluated both in silico and experimentally. The in silico analysis was implemented through multiphysics simulations with the software COMSOL Multiphysics 5.5® (COMSOL Inc., Stockholm, Sweden) via both a Eulerian model and a transport of diluted species model. The encapsulation efficiency was determined experimentally, aided by spectrofluorimetry. Encapsulation efficiencies obtained experimentally and in silico approached 80% for the highest flow rate ratios (FRRs). Compared with the passive mixer, the in silico results of the device under acoustic waves led to higher discrepancies with respect to those obtained experimentally. This was attributed to the complexity of the process in such a situation. The obtained MLPs demonstrated successful encapsulation of the nanobioconjugates by both methods with a 36% reduction in size for the ones obtained in the presence of ultrasound. These findings suggest that the proposed serpentine micromixers are well suited to produce MLPs very efficiently and with homogeneous key physichochemical properties.
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Ober, Thomas J., Daniele Foresti, and Jennifer A. Lewis. "Active mixing of complex fluids at the microscale." Proceedings of the National Academy of Sciences 112, no. 40 (September 22, 2015): 12293–98. http://dx.doi.org/10.1073/pnas.1509224112.
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Mixing of complex fluids at low Reynolds number is fundamental for a broad range of applications, including materials assembly, microfluidics, and biomedical devices. Of these materials, yield stress fluids (and gels) pose the most significant challenges, especially when they must be mixed in low volumes over short timescales. New scaling relationships between mixer dimensions and operating conditions are derived and experimentally verified to create a framework for designing active microfluidic mixers that can efficiently homogenize a wide range of complex fluids. Active mixing printheads are then designed and implemented for multimaterial 3D printing of viscoelastic inks with programmable control of local composition.
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Fallahi, Hedieh, Jun Zhang, Hoang-Phuong Phan, and Nam-Trung Nguyen. "Flexible Microfluidics: Fundamentals, Recent Developments, and Applications." Micromachines 10, no. 12 (November 29, 2019): 830. http://dx.doi.org/10.3390/mi10120830.
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Miniaturization has been the driving force of scientific and technological advances over recent decades. Recently, flexibility has gained significant interest, particularly in miniaturization approaches for biomedical devices, wearable sensing technologies, and drug delivery. Flexible microfluidics is an emerging area that impacts upon a range of research areas including chemistry, electronics, biology, and medicine. Various materials with flexibility and stretchability have been used in flexible microfluidics. Flexible microchannels allow for strong fluid-structure interactions. Thus, they behave in a different way from rigid microchannels with fluid passing through them. This unique behaviour introduces new characteristics that can be deployed in microfluidic applications and functions such as valving, pumping, mixing, and separation. To date, a specialised review of flexible microfluidics that considers both the fundamentals and applications is missing in the literature. This review aims to provide a comprehensive summary including: (i) Materials used for fabrication of flexible microfluidics, (ii) basics and roles of flexibility on microfluidic functions, (iii) applications of flexible microfluidics in wearable electronics and biology, and (iv) future perspectives of flexible microfluidics. The review provides researchers and engineers with an extensive and updated understanding of the principles and applications of flexible microfluidics.
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Baghaei, Masoud, and Josep M. Bergada. "Analysis of the Forces Driving the Oscillations in 3D Fluidic Oscillators." Energies 12, no. 24 (December 11, 2019): 4720. http://dx.doi.org/10.3390/en12244720.
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One of the main advantages of fluidic oscillators is that they do not have moving parts, which brings high reliability whenever being used in real applications. To use these devices in real applications, it is necessary to evaluate their performance, since each application requires a particular injected fluid momentum and frequency. In this paper, the performance of a given fluidic oscillator is evaluated at different Reynolds numbers via a 3D-computational fluid dynamics (CFD) analysis. The net momentum applied to the incoming jet is compared with the dynamic maximum stagnation pressure in the mixing chamber, to the dynamic output mass flow, to the dynamic feedback channels mass flow, to the pressure acting to both feedback channels outlets, and to the mixing chamber inlet jet oscillation angle. A perfect correlation between these parameters is obtained, therefore indicating the oscillation is triggered by the pressure momentum term applied to the jet at the feedback channels outlets. The paper proves that the stagnation pressure fluctuations appearing at the mixing chamber inclined walls are responsible for the pressure momentum term acting at the feedback channels outlets. Until now it was thought that the oscillations were driven by the mass flow flowing along the feedback channels, however in this paper it is proved that the oscillations are pressure driven. The peak to peak stagnation pressure fluctuations increase with increasing Reynolds number, and so does the pressure momentum term acting onto the mixing chamber inlet incoming jet.
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Furusawa, Hiroaki, Koichi Suzumori, Takefumi Kanda, Akinori Muto, and Yusaku Sakata. "Realizing Spiral Laminar Flow Interfaces with Improved Micro Rotary Reactor." Journal of Robotics and Mechatronics 21, no. 2 (April 20, 2009): 179–85. http://dx.doi.org/10.20965/jrm.2009.p0179.
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Research and development of micro-fluidic systems, such as μ-TAS and micro reactor system, has recently become active in the fields of chemical engineering and biotechnology. Micro mixing devices are an essential element in the realization of micro-fluidic systems. Therefore, in this research, a micro rotary reactor has been developed as a micro mixing device incorporated into micro-fluidic systems. The micro rotary reactor can form spiral laminar flow interfaces of two liquids through the rotation of a rotor. The spiral laminar flow interfaces increases the length and surface area of the reaction area between two liquids. But the previous prototype micro rotary reactor was only able to form spiral laminar flow interfaces under certain conditions. Therefore, the micro rotary reactor has been improved to form stable spiral laminar flow interfaces under a greater number of conditions. The full length and diameter of the improved micro rotary reactor are 60 mm and 15 mm, respectively. Experiments have shown that the improved micro rotary reactor can form spiral laminar flow interfaces under more varied conditions. This paper details the structure and the characteristics of the improved micro rotary reactor, as well as the experiments on its ability to form spiral laminar flow interfaces.
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Shah, Imran, Emad Uddin, Aamir Mubashar, Muhammad Yamin Younis, Hudair Samad, and Kyung Hyun choi. "Numerical Investigation of Surface Acoustic Wave (SAW) Interacting with a Droplet for Point-of-Care Devices." International Journal of Acoustics and Vibration 24, no. 4 (December 31, 2019): 632–37. http://dx.doi.org/10.20855/ijav.2019.24.41312.
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A three-dimensional numerical simulation of the interaction of a surface acoustic wave (SAW) with a droplet of water is carried out. The mixing produced inside the droplet due to the incident with the SAW and the droplet is investigated by undertaking a parametric study, with parameters such as frequency, drop size, and the lateral position of the droplet on the surface of the substrate. The linear relationship between the input voltage and the mixing velocity inside the droplet is obtained with variation of the input voltage of the inter-digital transducer (IDT) of the SAW device within a 10--40 V range. With the variation in frequency, the maximum mixing velocity is observed at 20 MHz and it appears to be independent of the size of the droplet. Varying the substrate material with lead zirconate titanate and lithium niobate produces better mixing. Lithium niobate is preferred due to its availability and cost-effectiveness. A drop of 600 um diameter produces better mixing. The different velocities inside the drop and the SAW device are obtained by changing the droplet position in the lateral direction (asymmetrical position) from the centre of the substrate. Cut planes parallel and perpendicular to the SAW at the core of a half-spherical droplet are observed to visualise the mixing effects inside the droplet during the interaction. To achieve the best mixing criteria, the droplet is moved in a lateral direction. An efficient parametric design for the mixing phenomena in micro-fluidic devices is presented for point-of-care devices.
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Pugia, Michael J., Gert Blankenstein, Ralf-Peter Peters, James A. Profitt, Klaus Kadel, Thomas Willms, Ronald Sommer, Hai Hang Kuo, and Lloyd S. Schulman. "Microfluidic Tool Box as Technology Platform for Hand-Held Diagnostics." Clinical Chemistry 51, no. 10 (October 1, 2005): 1923–32. http://dx.doi.org/10.1373/clinchem.2005.052498.
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Abstract Background: Use of microfluidics in point-of-care testing (POCT) will require on-board fluidics, self-contained reagents, and multistep reactions, all at a low cost. Disposable microchips were studied as a potential POCT platform. Methods: Micron-sized structures and capillaries were embedded in disposable plastics with mechanisms for fluidic control, metering, specimen application, separation, and mixing of nanoliter to microliter volumes. Designs allowed dry reagents to be on separate substrates and liquid reagents to be added. Control of surface energy to ±5 dyne/cm2 and mechanical tolerances to ≤1 μm were used to control flow propulsion into adsorptive, chromatographic, and capillary zones. Fluidic mechanisms were combined into working examples for urinalysis, blood glucose, and hemoglobin A1c testing using indicators (substances that react with analyte, such as dyes, enzyme substrates, and diazonium salts), catalytic reactions, and antibodies as recognition components. Optical signal generation characterized fluid flow and allowed detection. Results: We produced chips that included capillary geometries from 10 to 200 μm with geometries for stopping and starting the flow of blood, urine, or buffer; vented chambers for metering and splitting 100 nL to 30 μL; specimen inlets for bubble-free specimen entry and containment; capillary manifolds for mixing; microstructure interfaces for homogeneous transfer into separation membranes; miniaturized containers for liquid storage and release; and moisture vapor barrier seals for easy use. Serum was separated from whole blood in <10 s. Miniaturization benefits were obtained at 10–200 μm. Conclusion: Disposable microchip technology is compatible with conventional dry-reagent technology and allows a highly compact system for complex assay sequences with minimum manual manipulations and simple operation.
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Mercke, William L., Thomas Dziubla, Richard E. Eitel, and Kimberly Anderson. "Improved Trans-endothelial Electrical Resistance Sensing using Microfluidic Low-Temperature Co-fired Ceramics." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2013, CICMT (September 1, 2013): 000162–67. http://dx.doi.org/10.4071/cicmt-wp31.
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Trans-endothelial Electrical Resistance (TEER) and cellular impedance measurements are widely used to evaluate the barrier properties and functional change of endothelial cell monolayers. In the current work, low temperature cofired ceramics (LTCC) are applied enabling the incorporation of TEER and impediametric measurements in an integrated microfluidic chip. LTCC materials are an ideal substrate for biomedical and cell-based microfluidics due to their biocompatibility and ability to combine complex three dimensional structures with optical, fluidic, and electrical functionality. Multilayer microfluidic ceramic devices incorporating gold measurement electrodes where prepared using standard LTCC manufacturing procedures. The sensitivity of the resulting LTCC devices were compared to systems currently on the market for TEER measurements. These results indicate the LTCC device is able to effectively detect the growth of an endothelial cell monolayer. Results further evaluate endothelial cell viability using electrical resistance and Live/Dead assay. Finally, the results from this study also display improved sensitivity through the optimization of the electrode geometry and use of a lock-in amplifier. These results provide a solid basis for using low temperature co-fired ceramic materials for microfluidic TEER devices.
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Miyazaki, Celina M., Eadaoin Carthy, and David J. Kinahan. "Biosensing on the Centrifugal Microfluidic Lab-on-a-Disc Platform." Processes 8, no. 11 (October 28, 2020): 1360. http://dx.doi.org/10.3390/pr8111360.
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Lab-on-a-Disc (LoaD) biosensors are increasingly a promising solution for many biosensing applications. In the search for a perfect match between point-of-care (PoC) microfluidic devices and biosensors, the LoaD platform has the potential to be reliable, sensitive, low-cost, and easy-to-use. The present global pandemic draws attention to the importance of rapid sample-to-answer PoC devices for minimising manual intervention and sample manipulation, thus increasing the safety of the health professional while minimising the chances of sample contamination. A biosensor is defined by its ability to measure an analyte by converting a biological binding event to tangible analytical data. With evolving manufacturing processes for both LoaDs and biosensors, it is becoming more feasible to embed biosensors within the platform and/or to pair the microfluidic cartridges with low-cost detection systems. This review considers the basics of the centrifugal microfluidics and describes recent developments in common biosensing methods and novel technologies for fluidic control and automation. Finally, an overview of current devices on the market is provided. This review will guide scientists who want to initiate research in LoaD PoC devices as well as providing valuable reference material to researchers active in the field.
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Italia, Valeria, Argyro Giakoumaki, Silvio Bonfadini, Vibhav Bharadwaj, Thien Le Phu, Shane Eaton, Roberta Ramponi, Giacomo Bergamini, Guglielmo Lanzani, and Luigino Criante. "Laser-Inscribed Glass Microfluidic Device for Non-Mixing Flow of Miscible Solvents." Micromachines 10, no. 1 (December 29, 2018): 23. http://dx.doi.org/10.3390/mi10010023.
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In recent years, there has been significant research on integrated microfluidic devices. Microfluidics offer an advantageous platform for the parallel laminar flow of adjacent solvents of potential use in modern chemistry and biology. To reach that aim, we worked towards the realization of a buried microfluidic Lab-on-a-Chip which enables the separation of the two components by exploiting the non-mixing properties of laminar flow. To fabricate the aforementioned chip, we employed a femtosecond laser irradiation technique followed by chemical etching. To optimize the configuration of the chip, several geometrical and structural parameters were taken into account. The diffusive mass transfer between the two fluids was estimated and the optimal chip configuration for low diffusion rate of the components was defined.
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Figeys, D., and R. Aebersold. "Microfabricated Modules for Sample Handling, Sample Concentration and Flow Mixing: Application to Protein Analysis by Tandem Mass Spectrometry." Journal of Biomechanical Engineering 121, no. 1 (February 1, 1999): 7–12. http://dx.doi.org/10.1115/1.2798048.
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The comprehensive analysis of biological systems requires a combination of genomic and proteomic efforts. The large-scale application of current genomic technologies provides complete genomic DNA sequences, sequence tags for expressed genes (EST’s), and quantitative profiles of expressed genes at the mRNA level. In contrast, protein analytical technology lacks the sensitivity and the sample throughput for the systematic analysis of all the proteins expressed by a tissue or cell. The sensitivity of protein analysis technology is primarily limited by the loss of analytes, due to adsorption to surfaces, and sample contamination during handling. Here we summarize our work on the development and use of microfabricated fluidic systems for the manipulation of minute amounts of peptides and delivery to an electrospray ionization tandem mass spectrometer. New data are also presented that further demonstrate the potential of these novel approaches. Specifically, we describe the use of microfabricated devices as modules to deliver femtomole amounts of protein digests to the mass spectrometer for protein identification. We also describe the use of a microfabricated module for the generation of solvent gradients at nl/min flow rates for gradient chromatography-tandem mass spectrometry. The use of microfabricated fluidic systems reduces the risk of sample contamination and sample loss due to adsorption to wetted surfaces. The ability to assemble dedicated modular systems and to operate them automatically makes the use of microfabricated systems attractive for the sensitive and large-scale analysis of proteins.
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Hejazian, Majid, Eugeniu Balaur, and Brian Abbey. "Recent Advances and Future Perspectives on Microfluidic Mix-and-Jet Sample Delivery Devices." Micromachines 12, no. 5 (May 7, 2021): 531. http://dx.doi.org/10.3390/mi12050531.
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The integration of the Gas Dynamic Virtual Nozzle (GDVN) and microfluidic technologies has proven to be a promising sample delivery solution for biomolecular imaging studies and has the potential to be transformative for a range of applications in physics, biology, and chemistry. Here, we review the recent advances in the emerging field of microfluidic mix-and-jet sample delivery devices for the study of biomolecular reaction dynamics. First, we introduce the key parameters and dimensionless numbers involved in their design and characterisation. Then we critically review the techniques used to fabricate these integrated devices and discuss their advantages and disadvantages. We then summarise the most common experimental methods used for the characterisation of both the mixing and jetting components. Finally, we discuss future perspectives on the emerging field of microfluidic mix-and-jet sample delivery devices. In summary, this review aims to introduce this exciting new topic to the wider microfluidics community and to help guide future research in the field.
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Mahmud, Fahizan, Khairul Fikri Tamrin, Shahrol Mohamaddan, and Nobuo Watanabe. "Effect of Thermal Energy and Ultrasonication on Mixing Efficiency in Passive Micromixers." Processes 9, no. 5 (May 18, 2021): 891. http://dx.doi.org/10.3390/pr9050891.
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Micromixing is a key process in microfluidics technology. However, rapid and efficient fluid mixing is difficult to achieve inside the microchannels due to unfavourable laminar flow. Active micromixers employing ultrasound and thermal energy are effective in enhancing the micromixing process; however, integration of these energy sources within the devices is a non-trivial task. In this study, ultrasound and thermal energy have been extraneously applied at the upstream of the micromixer to significantly reduce fabrication complexity. A novel Dean micromixer was laser-fabricated to passively increase mixing performance and compared with T- and Y-micromixers at Reynolds numbers between 5 to 100. The micromixers had a relatively higher mixing index at lower Reynolds number, attributed to higher residence time. Dean micromixer exhibits higher mixing performance (about 27% better) than T- and Y-micromixers for 40 ≤ Re ≤ 100. Influence of ultrasound and heat on mixing is more significant at 5 ≤ Re ≤ 20 due to the prolonged mechanical effects. It can be observed that mixing index increases by about 6% to 10% once the temperature of the sonicated fluids increases from 30 °C to 60 °C. The proposed method is potentially useful as direct contact of the inductive energy sources may cause unwanted substrate damage and structural deformation especially for applications in biological analysis and chemical synthesis.
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Markovic, Tomislav, Juncheng Bao, Gertjan Maenhout, Ilja Ocket, and Bart Nauwelaers. "An Interdigital Capacitor for Microwave Heating at 25 GHz and Wideband Dielectric Sensing of nL Volumes in Continuous Microfluidics." Sensors 19, no. 3 (February 10, 2019): 715. http://dx.doi.org/10.3390/s19030715.
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This paper proposes a miniature microwave-microfluidic chip based on continuous microfluidics and a miniature interdigital capacitor (IDC). The novel chip consists of three individually accessible heaters, three platinum temperature sensors and two liquid cooling and mixing zones. The IDC is designed to achieve localized, fast and uniform heating of nanoliter volumes flowing through the microfluidic channel. The heating performance of the IDC located on the novel chip was evaluated using a fluorescent dye (Rhodamine B) diluted in demineralized water on a novel microwave-optical-fluidic (MOF) measurement setup. The MOF setup allows simultaneous microwave excitation of the IDC by means of a custom-made printed circuit board (connected to microwave equipment) placed in a top stage of a microscope, manipulation of liquid flowing through the channel located over the IDC with a pump and optical inspection of the same liquid flowing over the IDC using a fast camera, a light source and the microscope. The designed IDC brings a liquid volume of around 1.2 nL from room temperature to 100 °C in 21 ms with 1.58 W at 25 GHz. Next to the heating capability, the designed IDC can dielectrically sense the flowing liquid. Liquid sensing was evaluated on different concentration of water-isopropanol mixtures, and a reflection coefficient magnitude change of 6 dB was recorded around 8.1 GHz, while the minimum of the reflection coefficient magnitude shifted in the same frequency range for 60 MHz.
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González Fernández, Cristina, Jenifer Gómez Pastora, Arantza Basauri, Marcos Fallanza, Eugenio Bringas, Jeffrey J. Chalmers, and Inmaculada Ortiz. "Continuous-Flow Separation of Magnetic Particles from Biofluids: How Does the Microdevice Geometry Determine the Separation Performance?" Sensors 20, no. 11 (May 27, 2020): 3030. http://dx.doi.org/10.3390/s20113030.
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The use of functionalized magnetic particles for the detection or separation of multiple chemicals and biomolecules from biofluids continues to attract significant attention. After their incubation with the targeted substances, the beads can be magnetically recovered to perform analysis or diagnostic tests. Particle recovery with permanent magnets in continuous-flow microdevices has gathered great attention in the last decade due to the multiple advantages of microfluidics. As such, great efforts have been made to determine the magnetic and fluidic conditions for achieving complete particle capture; however, less attention has been paid to the effect of the channel geometry on the system performance, although it is key for designing systems that simultaneously provide high particle recovery and flow rates. Herein, we address the optimization of Y-Y-shaped microchannels, where magnetic beads are separated from blood and collected into a buffer stream by applying an external magnetic field. The influence of several geometrical features (namely cross section shape, thickness, length, and volume) on both bead recovery and system throughput is studied. For that purpose, we employ an experimentally validated Computational Fluid Dynamics (CFD) numerical model that considers the dominant forces acting on the beads during separation. Our results indicate that rectangular, long devices display the best performance as they deliver high particle recovery and high throughput. Thus, this methodology could be applied to the rational design of lab-on-a-chip devices for any magnetically driven purification, enrichment or isolation.
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Noël, Florian, Christophe Serra, and Stéphane Le Calvé. "Design of a Novel Axial Gas Pulses Micromixer and Simulations of its Mixing Abilities via Computational Fluid Dynamics." Micromachines 10, no. 3 (March 23, 2019): 205. http://dx.doi.org/10.3390/mi10030205.
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Following the fast development of microfluidics over the last decade, the need for methods for mixing two gases in flow at an overall flow rate ranging from 1 to 100 NmL·min−1 with programmable mixing ratios has been quickly increasing in many fields of application, especially in the calibration of analytical devices such as air pollution sensors. This work investigates numerically the mixing of pure gas pulses at flow rates in the range 1–100 NmL·min−1 in a newly designed multi-stage and modular micromixer composed of 4 buffer tanks of 300 µL each per stage. Results indicate that, for a 1 s pulse of pure gas (formaldehyde) followed by a 9 s pulse of pure carrier gas (air), that is a pulses ratio of 1/10, an effective mixing up to 94–96% can be readily obtained at the exit of the micromixer. This is achieved in less than 20 s for any flow rate ranging from 1 to 100 NmL·min−1 simply by adjusting the number of stages, 1 to 16 respectively. By using an already diluted gas bottle containing 100 ppm of a given compound in an inert gas same as the carrier gas, concentrations ranging from 10 to 90 ppm should be obtained by adjusting the pulses ratio between 1/10 and 9/10 respectively.