Journal articles on the topic 'Micromixer'
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1
Natsuhara, Daigo, Ryogo Saito, Shunya Okamoto, Moeto Nagai, and Takayuki Shibata. "Mixing Performance of a Planar Asymmetric Contraction-and-Expansion Micromixer." Micromachines 13, no. 9 (August 25, 2022): 1386. http://dx.doi.org/10.3390/mi13091386.
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Micromixers are one of the critical components in microfluidic devices. They significantly affect the efficiency and sensitivity of microfluidics-based lab-on-a-chip systems. This study introduces an efficient micromixer with a simple geometrical feature that enables easy incorporation in a microchannel network without compromising the original design of microfluidic devices. The study proposes a newly designed planar passive micromixer, termed a planar asymmetric contraction-and-expansion (P-ACE) micromixer, with asymmetric vertical obstacle structures. Numerical simulation and experimental investigation revealed that the optimally designed P-ACE micromixer exhibited a high mixing efficiency of 80% or more within a microchannel length of 10 mm over a wide range of Reynolds numbers (0.13 ≤ Re ≤ 13), eventually attaining approximately 90% mixing efficiency within a 20 mm microchannel length. The highly asymmetric geometric features of the P-ACE micromixers enhance mixing because of their synergistic effects. The flow velocities and directions of the two fluids change differently while alternately crossing the longitudinal centerline of the microchannel, with the obstacle structures asymmetrically arranged on both sidewalls of the rectangular microchannel. This flow behavior increases the interfacial contact area between the two fluids, thus promoting effective mixing in the P-ACE micromixer. Further, the pressure drops in the P-ACE micromixers were experimentally investigated and compared with those in a serpentine micromixer with a perfectly symmetric mixing unit.
2
Zulkarnain, M. H., A. A. Ma’ Radzi, and M. M. Abdul Jamil. "Consideration of Obstacles Configuration in Designing Low Reynolds Number Micromixer for Blood Microfluidic Application." Applied Mechanics and Materials 679 (October 2014): 212–16. http://dx.doi.org/10.4028/www.scientific.net/amm.679.212.
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Micromixer can be divided into two categories which are active micromixer and passive micromixer. Due to the simple fabrication technology and ease of implementation in a complex microfluidic system, obstacle-based passive micromixers will be the focus in this work. A passive micromixer is depends on low Reynolds number and the channel geometry for mixing effectiveness. In this work, three designs of obstacle based micromixer were designed and evaluated. These micromixers has 237μm channel length, 30μm inlet length, 900 between inlets ports, width and depth are 30μm each. The fluids used for mixing were blood which has 3.0 × 10-3 kg/μms of viscosity and glycerin which has high viscosity than blood (1.49 × 10-3 kg/μms). The fluids used to evaluate the differences in term of their visual performance based image’s standard deviation by plotting the graph and mixing efficiency by calculation. Based on these evaluations, the Y shape with meander structure obstacle design has the best mixing efficiency at the outlet of the channel.
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Wang, Chin-Tsan, Yan-Ming Chen, Pei-An Hong, and Yi-Ta Wang. "Tesla Valves in Micromixers." International Journal of Chemical Reactor Engineering 12, no. 1 (January 1, 2014): 397–403. http://dx.doi.org/10.1515/ijcre-2013-0106.
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Abstract Micromixers are the devices which have the ability to mix liquids uniformly. However, a Tesla valve has the potential for micromixer development because of its simple structure and special flow mechanism. In this study, a numerical simulation analysis of a new Tesla-type micromixer was designed by placing a flow plate into a micromixer, which has a contact angle of 30° with the channel wall. The optimization of the geometric parameter, aspect ratio (AR) and the Reynolds number (Re) effect is discussed. The results show that the optimal geometric parameters of the unit Tesla-type micromixer are θ1 = 45°, θ2 = 30°, A = 0.3 mm, B = 0.22 mm, C = 0.3 mm, D = 0.25 mm, and the mixing efficiency can achieve εmixing = 0.953 by passing three-unit Tesla-type micromixers (inverse-type, Re = 1, AR = 1). The Tesla-type micromixers designed in this study, which have a lower pressure drop and a higher mixing performance at a low Reynolds number, can contribute to the application of biomedical chips and chemical reactors.
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Chen, Xue Ye, and Yuan He. "Optimal Design and Simulation for a Bio-Inspired Micromixer Based on Blood Transport in Vessel." Materials Science Forum 852 (April 2016): 1288–92. http://dx.doi.org/10.4028/www.scientific.net/msf.852.1288.
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A novel design concept for micromixer based on blood transport bionic principle has been presented. The bio-inspired micromixer based on blood transport in blood vessel is simulated to obtain a desired mixing efficiency. The flow rate, sample concentration distribution, channel width ratio, and channel arrangement as operating factors were researched to evaluate the mixing performance. The simulation results show the micromixer can give a high performance with the optimized simple structure. The bionic micromixer is proven to be effective for enhancing sample mixing and will have great potential to instruct design of micromixers.
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Khaydarov, Valentin, Ekaterina Borovinskaya, and Wladimir Reschetilowski. "Numerical and Experimental Investigations of a Micromixer with Chicane Mixing Geometry." Applied Sciences 8, no. 12 (December 2, 2018): 2458. http://dx.doi.org/10.3390/app8122458.
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A micromixer is a new type of chemical engineering equipment used to intensify the mixing process. This article provides details on flow regimes in microchannels with a complex geometry, such as with chicane mixing geometry. Experiments involving water, ink, and a micro digital camera have determined both the micromixer’s initial mixing zone, and also the streamlines. Computational fluid dynamics (CFD) modelling helped identify the mechanism of stimulating effect; swirling and recirculation were identified as two special cases of the convective mixing process. To characterize the degree of mixing, a function of volume flow rate was proposed. A much higher degree of mixing in vortex flow compared to stratified flow was observed. The relationship between laminar flow and vortices shows a square-law dependence of pressure drop against the volume flow rate. The mixing cost and the mixing energy cost at Reynolds number of 50 are higher for the chicane micromixer than for micromixers without chicanes geometry.
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Qi, Jia, Wenbo Li, Wei Chu, Jianping Yu, Miao Wu, Youting Liang, Difeng Yin, et al. "A Microfluidic Mixer of High Throughput Fabricated in Glass Using Femtosecond Laser Micromachining Combined with Glass Bonding." Micromachines 11, no. 2 (February 19, 2020): 213. http://dx.doi.org/10.3390/mi11020213.
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We demonstrate a microfluidic mixer of high mixing efficiency in fused silica substrate using femtosecond laser-induced wet etching and hydroxide-catalysis bonding method. The micromixer has a three-dimensional geometry, enabling efficient mixing based on Baker’s transformation principle. The cross-sectional area of the fabricated micromixer was 0.5 × 0.5 mm2, enabling significantly promotion of the throughput of the micromixer. The performance of the fabricated micromixers was evaluated by mixing up blue and yellow ink solutions with a flow rate as high as 6 mL/min.
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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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Chen, Zhong, Yalin Wang, and Song Zhou. "Numerical Analysis of Mixing Performance in an Electroosmotic Micromixer with Cosine Channel Walls." Micromachines 13, no. 11 (November 9, 2022): 1933. http://dx.doi.org/10.3390/mi13111933.
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Micromixers have significant potential in the field of chemical synthesis and biological pharmaceuticals, etc. In this study, the design and numerical simulations of a passive micromixer and a novel active electroosmotic micromixer by assembling electrode pairs were both presented with a cosine channel wall. The finite element method (FEM) coupled with Multiphysics modeling was used. To propose an efficient micromixer structure, firstly, different geometrical parameters such as amplitude-to-wavelength ratio (a/c) and mixing units (N) in the steady state without an electric field were investigated. This paper aims to seek a high-quality mixing solution. Therefore, based on the optimization of the above parameters of the passive micromixer, a new type of electroosmotic micromixer with an AC electric field was proposed. The results show that the vortices generated by electroosmosis can effectively induce fluid mixing. The effects of key parameters such as the Reynolds number, the number of electrode pairs, phase shift, voltage, and electrode frequency on the mixing performance were specifically discussed through numerical analysis. The mixing efficiency of the electroosmotic micromixer is quantitatively analyzed, which can be achieved at 96%. The proposed micromixer has a simple structure that can obtain a fast response and high mixing index.
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Raza, Wasim, Shakhawat Hossain, and Kwang-Yong Kim. "A Review of Passive Micromixers with a Comparative Analysis." Micromachines 11, no. 5 (April 27, 2020): 455. http://dx.doi.org/10.3390/mi11050455.
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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.
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da Cunha, Marcio Rodrigues, Antonio Carlos Seabra, and Mário R. Gongora-Rubio. "LTCC 3D MICROMIXER OPTIMIZATION FOR PROCESS INTENSIFICATION." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2012, CICMT (September 1, 2012): 000563–72. http://dx.doi.org/10.4071/cicmt-2012-tha13.
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Mixing of fluids is a very important unit operation for Chemical, Biochemical, & Pharmaceutical processes among others, with a great deal of interest for industrial and research sectors. Micromixers a new implementation in micro scale of mixers are being studied. Active (electrokinetic, pressure disturbances, ultrasonic, magneto-hydrodynamic) and passive (jet breakup, vortex, microchannels ) methods appear in the literature. In particular research of micromixers with microchannels having different kind of elbows are conducted focusing hydrodynamic phenomena in microscale, like caotic advection. LTCC Microsystem Technology is suitable for the construction of micromixers because their inherent capacity of implementing 2D and 3D structures. The goal of the present work is to report our current study on LTCC micromixers based on microchannels having different kind of elbows for geometry optimization applying finite element Computational Fluid Dynamic numerical methods for process chemical intensification. The study will contemplate nine different 2D and 3D LTCC micromixer geometries compared with straight channel micromixer and prospect hydrodynamic parameters as: flow rate, pressure difference, friction factor and head loss coefficient. It is also presented a description of flowage as a function of diffusion-convection equation in order to obtain the mixing performance of designed devices.
11
Yang, Can, Xiao Hong Yin, Lei Li, Jose M. Castro, and Allen Y. Yi. "Microinjection Molding of Polymer Micromixers for Biomedical Application." Applied Mechanics and Materials 138-139 (November 2011): 941–45. http://dx.doi.org/10.4028/www.scientific.net/amm.138-139.941.
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In recent years, microinjection molding has been widely used for fabricating polymer components due to its cost effectiveness and mass-production capability. In this work, the fabrication process of a polymer micromixer was presented. The micromixer was designed in such a way that the fabrication process could benefit from the process capabilities of ultraprecision micromachining and microinjection molding. An amorphous polymer material polymethylmethacrylate was used to make the micromixers. Moreover, in order to investigate the effects of processing parameters on replication quality of the micromixer, four important factors in microinjection molding, namely the melt temperature, injection velocity, packing pressure and packing time were selected as variables. The experimental results showed that the melt temperature was the most important factor influencing the replication, followed by the injection velocity. However, the packing pressure and packing time had no obvious influence on the replication of the micromixer.
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Malecha, Ziemowit M., and Karol Malecha. "Numerical Analysis Of Mixing Under Low And High Frequency Pulsations At Serpentine Micromixers." Chemical and Process Engineering 35, no. 3 (September 1, 2014): 369–85. http://dx.doi.org/10.2478/cpe-2014-0028.
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Abstract The numerical investigation of the mixing process in complex geometry micromixers, as a function of various inlet conditions and various micromixer vibrations, was performed. The examined devices were two-dimensional (2D) and three-dimensional (3D) types of serpentine micromixers with two inlets. Entering fluids were perturbed with a wide range of the frequency (0 - 50 Hz) of pulsations. Additionally, mixing fluids also entered in the same or opposite phase of pulsations. The performed numerical calculations were 3D to capture the proximity of all the walls, which has a substantial influence on microchannel flow. The geometry of the 3D type serpentine micromixer corresponded to the physically existing device, characterised by excellent mixing properties but also a challenging production process (Malecha et al., 2009). It was shown that low-frequency perturbations could improve the average mixing efficiency of the 2D micromixer by only about 2% and additionally led to a disadvantageously non-uniform mixture quality in time. It was also shown that high-frequency mixing could level these fluctuations and more significantly improve the mixing quality. In the second part of the paper a faster and simplified method of evaluation of mixing quality was introduced. This method was based on calculating the length of the contact interface between mixing fluids. It was used to evaluate the 2D type serpentine micromixer performance under various types of vibrations and under a wide range of vibration frequencies.
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Okuducu, Mahmut Burak, and Mustafa M. Aral. "Toward the Next Generation of Passive Micromixers: A Novel 3-D Design Approach." Micromachines 12, no. 4 (March 30, 2021): 372. http://dx.doi.org/10.3390/mi12040372.
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Passive micromixers are miniaturized instruments that are used to mix fluids in microfluidic systems. In microchannels, combination of laminar flows and small diffusion constants of mixing liquids produce a difficult mixing environment. In particular, in very low Reynolds number flows, e.g., Re < 10, diffusive mixing cannot be promoted unless a large interfacial area is formed between the fluids to be mixed. Therefore, the mixing distance increases substantially due to a slow diffusion process that governs fluid mixing. In this article, a novel 3-D passive micromixer design is developed to improve fluid mixing over a short distance. Computational Fluid Dynamics (CFD) simulations are used to investigate the performance of the micromixer numerically. The circular-shaped fluid overlapping (CSFO) micromixer design proposed is examined in several fluid flow, diffusivity, and injection conditions. The outcomes show that the CSFO geometry develops a large interfacial area between the fluid bodies. Thus, fluid mixing is accelerated in vertical and/or horizontal directions depending on the injection type applied. For the smallest molecular diffusion constant tested, the CSFO micromixer design provides more than 90% mixing efficiency in a distance between 260 and 470 µm. The maximum pressure drop in the micromixer is found to be less than 1.4 kPa in the highest flow conditioned examined.
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Zhang, He, Shuang Yang, Rongyan Chuai, Xin Li, and Xinyu Mu. "The Influence of the Unit Junction on the Performance of a Repetitive Structure Micromixer." Micromachines 13, no. 3 (February 27, 2022): 384. http://dx.doi.org/10.3390/mi13030384.
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In order to investigate the influence of the unit junction on the micromixer performance, a repetitive structure micromixer with a total length of 12.3 mm was proposed. This micromixer consists of a T-shape inlet channel and six cubic mixing units, as well as junctions between them. Numerical simulations show that, when the junctions are all located at the geometric center of the cubic mixing unit, the outlet mixing index is 72.12%. At the same flow velocity, the best mixing index achieved 97.15% and was increased by 34.68% when the junctions were located at different corners of the cubic mixing unit. The improvement in the mixing index illustrated that the non-equilibrium vortexes generated by changing the junction location to utilize the restricted diffusion by the mixing unit’s side wall could promote mixing. Visual tests of the micromixer chip prepared by 3D printing were consistent with the simulation results, also indicating that the junction location had a significant influence on the mixer’s performance. This article provides a new idea for optimizing the structural design and improving the performance of micromixers.
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Nai, Jiacheng, Feng Zhang, Peng Dong, Ting Fu, Anle Ge, Shuang Xu, and Yanqiao Pan. "Influence of Structural Parameters on the Performance of an Asymmetric Rhombus Micromixer with Baffles." Micromachines 14, no. 3 (February 26, 2023): 545. http://dx.doi.org/10.3390/mi14030545.
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As an important part of lab-on-a-chip and micro-total analysis systems, micromixers have a wide range of applications in biochemical analysis, pharmaceutical preparation and material synthesis. In the work, a novel rhombic separation and recombination micromixer with baffles was presented to further improve the performance of the micromixer and study the effect of multiple structural parameters on mixing. The effects of the rhombic angle, the width ratio of sub-channel and the size and relative positions of baffles on the mixing index were studied numerically at different Reynolds numbers (Re), and the sensitivity of the mixing index to various structures was also investigated. The results showed that the mixing index increased with the subchannel’s width ratio and slowly decreased after reaching the peak value in the range of Re from 0.1 to 60. The maximum mixing index appeared when the width ratio was 6.5. The pressure drops in the microchannel were proportional to the width ratio. The mixing effect can be further improved by adding baffle structure to asymmetric rhombus micromixer, and more baffle quantity and larger baffle height were beneficial to the improvement of the mixing index. The research results can provide reference and new ideas for the structure design of passive micromixers.
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Jalili, Habib, Mohammad Raad, and Davoud Abbasinezhad Fallah. "Numerical study on the mixing quality of an electroosmotic micromixer under periodic potential." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 234, no. 11 (February 5, 2020): 2113–25. http://dx.doi.org/10.1177/0954406220904089.
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Improvement of the mixing quality of low Reynolds number flows in micro-dimensional devices is essential. This paper investigates the optimization of the effective parameters and their effects on the mixing quality in a two-dimensional active micromixer. The micromixer mixes fluids with different concentrations entering into a microchannel from different inlets by means of four microelectrodes placed on the walls of a mixing chamber. A time-dependent electric field is applied, and the resulting electroosmotic force perturbs the parallel streamlines in the otherwise highly ordered laminar flow. The governing equations are numerically solved using the finite element-based COMSOL Multiphysics (Version 5.2a) software. The electroosmotic actuated active micromixer was numerically studied for various values of inlet velocity, phase lag, frequency, and voltage amplitude. Once the optimum values of the effective parameters are obtained for the original micromixer, they are applied to the micromixers having different obstacle shape inside the mixing chamber. The results showed that the mixing quality strongly depends on the inlet velocity of the fluids, the electrodes phase lag, the frequency, and the voltage amplitude. In addition, the mixing quality does not depend on obstacle shape when the optimum values of these parameters were used.
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Kim, Chul-Kyu, and Joon-Yong Yoon. "Optimal design of groove shape on passive micromixer using design of experiment technique." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 231, no. 4 (April 6, 2016): 880–87. http://dx.doi.org/10.1177/0954408916640663.
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Passive micromixers are one of the parts used for the mixing of two or more fluids in micro-electro-mechanical system devices, and they have been developed for various types. Fluid mixing in microscale devices is essential in microfluidic applications; however, it is difficult to mix fluids in microchannels due to the slowness of the molecular diffusion process at the microscale. In this study, optimization of the groove shape geometries of a micromixer using response surface design was performed, and the mixing performance was investigated through a numerical analysis applied with the passive scalar method. The most useful parameters were determined to be the geometric parameters of optimization, such as groove depth, groove length, distance between grooves, and groove angle. Response surface design, a design of experiments technique, was applied to the optimization procedure. The mixing index and pressure drop are important factors for evaluating the micromixer performance. Through the response surface design, this study aims to affect the groove shape of a passive micromixer. Consequently, it was concluded that the groove length and distance between grooves improved the mixing performance and decreased the pressure drop. In addition, optimal models were proposed for the passive micromixer.
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Jurina, Tamara, Ivana Čulo, Maja Benković, Jasenka Gajdoš Kljusurić, Davor Valinger, and Ana Jurinjak Tušek. "The Effect of Micromixer Geometry on the Diameters of Emulsion Droplets: NIR Spectroscopy and Artificial Neural Networks Modeling." Engineering Proceedings 4, no. 1 (April 27, 2021): 26. http://dx.doi.org/10.3390/micromachines2021-09658.
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In this work, teardrop micromixer and swirl micromixer were used for preparation of oil-in-water (O/W) emulsions with Tween 20 and PEG 2000 as emulsifiers (concentrations: 2% and 4%) at different total flow rates (20–280 µL/min). Stability of the prepared O/W emulsions was evaluated based on the droplet size of the dispersed phase. For determination of the droplet size, the average Feret diameter was used. Furthermore, near infrared (NIR) spectra of all prepared samples were collected. Obtained results showed that the change in the droplet size followed the same trend for both micromixers used in the experiment. At higher total flow rates, emulsification resulted in smaller values of the average Feret diameter. Values of the average Feret diameter were higher for emulsions prepared in the swirl micromixer, compared to the teardrop micromixer. Artificial Neural Network (ANNs) models, based on the recorded NIR spectra of emulsions, were developed to predict the droplet size of the dispersed phase. The obtained ANN models have high values of R2 for training, test, and validation, with small error values and show that NIR spectroscopy, in combination with ANNs, could be efficiently used for evaluation of the stability of oil-in-water emulsions.
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Ulkir, Osman, Oguz Girit, and Ishak Ertugrul. "Design and Analysis of a Laminar Diffusion-Based Micromixer with Microfluidic Chip." Journal of Nanomaterials 2021 (January 2, 2021): 1–10. http://dx.doi.org/10.1155/2021/6684068.
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This study aims to perform optimizatione to achieve the best diffusion control between the channels by designing and analysing a microfluidic-based micromixer. The design and analysis of the micromixer were made with the COMSOL Multiphysics program. Some input and output parameters must be defined for diffusion control of the micromixer. Among these parameters, inputs are the diffusion coefficient and inlet flow rate, while outputs are velocity, pressure, and concentration. Each input parameter in the microfluidic chip affects the output of the system. To make the diffusion control in the most optimum way, the data were obtained by making much analysis. The data obtained from this program was also provided with the Fuzzy Logic method to optimize the microfluidic chip. The diffusion coefficient value (5E-11 m2/s) should be given to the channels to achieve the optimum diffusion between the micromixer channels, if the inlet flow rate value (15E-15 m3/s) is the output value of the system, the velocity is 0.09 mm/s. The pressure is 2 Pa, and the concentration is 0.45 mol/m3. These values are the optimum values obtained from the analysis without damaging the liquid’s microfluidic channels supplied to the micromixer’s inlet.
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Rouhi, Omid, Sajad Razavi Bazaz, Hamid Niazmand, Fateme Mirakhorli, Sima Mas-hafi, Hoseyn A. Amiri, Morteza Miansari, and Majid Ebrahimi Warkiani. "Numerical and Experimental Study of Cross-Sectional Effects on the Mixing Performance of the Spiral Microfluidics." Micromachines 12, no. 12 (November 29, 2021): 1470. http://dx.doi.org/10.3390/mi12121470.
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Mixing at the microscale is of great importance for various applications ranging from biological and chemical synthesis to drug delivery. Among the numerous types of micromixers that have been developed, planar passive spiral micromixers have gained considerable interest due to their ease of fabrication and integration into complex miniaturized systems. However, less attention has been paid to non-planar spiral micromixers with various cross-sections and the effects of these cross-sections on the total performance of the micromixer. Here, mixing performance in a spiral micromixer with different channel cross-sections is evaluated experimentally and numerically in the Re range of 0.001 to 50. The accuracy of the 3D-finite element model was first verified at different flow rates by tracking the mixing index across the loops, which were directly proportional to the spiral radius and were hence also proportional to the Dean flow. It is shown that higher flow rates induce stronger vortices compared to lower flow rates; thus, fewer loops are required for efficient mixing. The numerical study revealed that a large-angle outward trapezoidal cross-section provides the highest mixing performance, reaching efficiencies of up to 95%. Moreover, the velocity/vorticity along the channel length was analyzed and discussed to evaluate channel mixing performance. A relatively low pressure drop (<130 kPa) makes these passive spiral micromixers ideal candidates for various lab-on-chip applications.
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ZHANG, SHUAI, XUEYE CHEN, ZHONGLI WU, and YUE ZHENG. "NUMERICAL STUDY ON KOCH FRACTAL BAFFLE MICROMIXER." Fractals 27, no. 03 (May 2019): 1950026. http://dx.doi.org/10.1142/s0218348x19500269.
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This paper is mainly to study the application of Koch fractal baffle to passive micromixers. It can be determined that the mixing efficiency of secondary Koch fractal baffle (SKFB) micromixer is better than that of primary Koch fractal baffle (PKFB). We compare and analyze the mixing efficiency when the angle between the baffle and the microchannel is [Formula: see text], [Formula: see text] and [Formula: see text] with the height 100[Formula: see text][Formula: see text]m. With the changing of the angle, it contributes to enhance the chaotic convection of the micromixer. Especially at the angle of [Formula: see text], the vortex caused by the Koch fractal baffle structure is more obvious, the mixing efficiency of micromixer is more than 95% at Re [Formula: see text] 0.05 and 100. When the height of Koch fractal baffle is 50, 75 and [Formula: see text]m, the mixing efficiency of the micromixer gradually increases. The whirling and spiral phenomenon of the streamlines increases the chaotic convection and promotes the improvement of the mixing efficiency. In the direction of microchannel, nine sections which have a significant effect on the mixing efficiency are investigated. The encircling and split phenomenon affected by the chaotic convection is shown in nine sections at Re [Formula: see text] 0.05, 10 and 100.
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Wu, Zhongli, Yu Li, Lei Xu, Dongmei Bao, Xiying Zhang, and Tingjian Zhang. "Numerical study of the passive micromixer with the novel blocks." AIP Advances 12, no. 4 (April 1, 2022): 045016. http://dx.doi.org/10.1063/5.0078400.
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The micromixer is a key component of the microfluidic chip analysis system. Micromixers are widely used in applications, such as DNA hybridization and protein synthesis. A high-efficiency mixer can speed up the biochemical analysis process. In order to study how to improve the mixing efficiency of the mixer, this paper designs passive micromixers with three different blocks: cylindrical, equilateral triangle, and square. The effects of them on the mixing performance and pressure drop of the mixer were studied, respectively. Through numerical simulation, the study shows that the mixing efficiency of the mixer with equilateral triangle blocks is 96% at Re = 100, and the maximum pressure drop is 18 135.8 Pa. In addition, through the analysis of three-dimensional numerical simulation, the block causes the fluid to generate a horizontal and vertical vortex flow state in the mixing unit, thereby breaking the laminar flow and greatly improving the mixing efficiency. Through structural optimization, ETOM4, which has four mixing units and a side length of 150 μm equilateral triangle blocks, is the best passive micromixer with its mixing efficiency of 99.1%.
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Okuducu, Mahmut, and Mustafa Aral. "Computational Evaluation of Mixing Performance in 3-D Swirl-Generating Passive Micromixers." Processes 7, no. 3 (February 27, 2019): 121. http://dx.doi.org/10.3390/pr7030121.
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Computational Fluid Dynamics (CFD) tools are used to investigate fluid flow and scalar mixing in micromixers where low molecular diffusivities yield advection dominant transport. In these applications, achieving a numerical solution is challenging. Numerical procedures used to overcome these difficulties may cause misevaluation of the mixing process. Evaluation of the mixing performance of these devices without appropriate analysis of the contribution of numerical diffusion yields over estimation of mixing performance. In this study, two- and four-inlet swirl-generating micromixers are examined for different mesh density, flow and molecular diffusivity scenarios. It is shown that mesh densities need to be high enough to reveal numerical diffusion errors in scalar transport simulations. Two-inlet micromixer design was found to produce higher numerical diffusion. In both micromixer configurations, when cell Peclet numbers were around 50 and 100 for Reynolds numbers 240 and 120, the numerical diffusion effects were tolerable. However, when large cell Peclet number scenarios were tested, it was found that the molecular diffusivity of the fluid is completely masked by false diffusion errors.
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Hsu, Hsiang Chen, Hsi Chien Liu, and Cheng Jiun Han. "Fabrication of Microfluidic Rapid Micromixer." Key Engineering Materials 467-469 (February 2011): 2013–17. http://dx.doi.org/10.4028/www.scientific.net/kem.467-469.2013.
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A microfluidic multi-cylindric rapid micromixer is fabricated in the present paper. The key features in the presented MEMS-based microchannel design are (1) micro pump (2) Y-junction type channel (3) cylindric obstacle (4) notch with the edge of sharp teeth. Two different fluids (DI water and red ink) were pumped and injected into Y-type channel, and the fluids were broken-up by a cylindric obstacle in the center of tapered microchannel. The chaotic convection occurs in the mixing channel behind the cylindric obstacle. The mixing index is defined to qualify the mixing efficiency, which demonstrates the outlet notch with sharp teeth along the sidewall plays an important role for mixing effects. The developed micromixer can enhance mixing using the mechanisms of diffusion and convection for wide range of Reynolds number (0.01<Re<100). Parametric studies for volumetric flow rate include the number of cylindric obstacles, the number of notches with sharp-teeth and the width of microchannel. Preliminary results demonstrate that the mixing index reaches the desired effect (<0.1) within 0.08 second when the inlet fluid velocity is 0.49992m/s, i.e. volumetric flow rate is 1200μl /min. The presented device is faster than most of reported micromixers.
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Guo, Wenpeng, Li Tang, Biqiang Zhou, and Yingsing Fung. "Fundamental Studies of Rapidly Fabricated On-Chip Passive Micromixer for Modular Microfluidics." Micromachines 12, no. 2 (February 4, 2021): 153. http://dx.doi.org/10.3390/mi12020153.
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Micromixers play an important role in many modular microfluidics. Complex on-chip mixing units and smooth channel surfaces ablated by lasers on polymers are well-known problems for microfluidic chip fabricating techniques. However, little is known about the ablation of rugged surfaces on polymer chips for mixing uses. This paper provides the first report of an on-chip compact micromixer simply, easily and quickly fabricated using laser-ablated irregular microspheric surfaces on a polymethyl methacrylate (PMMA) microfluidic chip for continuous mixing uses in modular microfluidics. The straight line channel geometry is designed for sequential mixing of nanoliter fluids in about 1 s. The results verify that up to about 90% of fluids can be mixed in a channel only 500 µm long, 200 µm wide and 150 µm deep using the developed micromixer fabricating method under optimized conditions. The computational flow dynamics simulation and experimental result agree well with each other.
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Juraeva, Makhsuda, and Dong-Jin Kang. "Optimal Combination of Mixing Units Using the Design of Experiments Method." Micromachines 12, no. 8 (August 19, 2021): 985. http://dx.doi.org/10.3390/mi12080985.
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A passive micromixer was designed by combining two mixing units: the cross-channel split and recombined (CC-SAR) and a mixing cell with baffles (MC-B). The passive micromixer was comprised of eight mixing slots that corresponded to four combination units; two mixing slots were grouped as one combination unit. The combination of the two mixing units was based on four combination schemes: (A) first mixing unit, (B) first combination unit, (C) first combination module, and (D) second combination module. The statistical significance of the four combination schemes was analyzed using analysis of variance (ANOVA) in terms of the degree of mixing (DOM) and mixing energy cost (MEC). The DOM and MEC were simulated numerically for three Reynolds numbers (Re = 0.5, 2, and 50), representing three mixing regimes. The combination scheme (B), using different mixing units in the first two mixing slots, was significant for Re = 2 and 50. The four combination schemes had little effect on the mixing performance of a passive micromixer operating in the mixing regime of molecular dominance. The combination scheme (B) was generalized to arbitrary mixing slots, and its significance was analyzed for Re = 2 and 50. The general combination scheme meant two different mixing units in two consecutive mixing slots. The numerical simulation results showed that the general combination scheme was statistically significant in the first three combination units for Re = 2, and significant in the first two combination units for Re = 50. The combined micromixer based on the general combination scheme throughout the entire micromixer showed the best mixing performance over a wide range of Reynolds numbers, compared to other micromixers that did not adopt completely the general combination scheme. The most significant enhancement due to the general combination scheme was observed in the transition mixing scheme and was negligible in the molecular dominance scheme. The combination order was less significant after three combination units.
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Kadam, Suraj S. "Mixing Behavior and Pressure Drop Analysis of Micromixer with Different Geometric Conditions." International Journal for Research in Applied Science and Engineering Technology 9, no. VI (June 20, 2021): 2008–16. http://dx.doi.org/10.22214/ijraset.2021.35393.
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A 3-D design of and analysis of fluid flow in the micromixer with different configurations is carried out in this dissertation. The main purpose of this research is to obtain minimum mixing length as rapid mixing is essential in many of the micro-fluidic systems used in biochemistry analysis, drug delivery, sequencing, or synthesis of nucleic acids. Also effect on various parameters such as mixing behavior, volume arrow, mixing length, maximum velocity, maximum pressure, pressure drop, and velocity distribution were analyzed by changing the mixing angle between inlets. Micromixers with square cross-section rectangular mixing chamber with various types of obstacle place in fluid flow paths such as rectangular obstacles, elliptical obstacle, and circular obstacle in split and recombination manner were designed for the analysis. The micromixer has 3 inlets and 1 outlet. Water and ethanol were used as working fluids. For computational fluid dynamics analysis, COMSOL Multiphysics 5.0 is used. From various results, we have found that size, the geometry of mixing chambers and obstacles, and mixing angle effect mixing length, pressure, and velocity. With a decrease in mixing angle mixing length, pressure drop, and maximum velocity decrease i.e it gives better mixing performance. Also with an increase in the number of obstacles mixing length and maximum velocity decreases and pressure drop increases. Micromixer with mixing angle 60 degree and circular obstacles gives minimum mixing length than any other models consisting rectangular or elliptical obstacle and mixing angle greater than 60 degrees.
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Wang, Chin-Tsan, Yuh-Chung Hu, and Tzu-Yang Hu. "Biophysical Micromixer." Sensors 9, no. 7 (July 8, 2009): 5379–89. http://dx.doi.org/10.3390/s90705379.
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Tesař, V. "Oscillator micromixer." Chemical Engineering Journal 155, no. 3 (December 2009): 789–99. http://dx.doi.org/10.1016/j.cej.2009.07.060.
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Mehrdel, Pouya, Shadi Karimi, Josep Farré-Lladós, and Jasmina Casals-Terré. "Novel Variable Radius Spiral–Shaped Micromixer: From Numerical Analysis to Experimental Validation." Micromachines 9, no. 11 (October 27, 2018): 552. http://dx.doi.org/10.3390/mi9110552.
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A novel type of spiral micromixer with expansion and contraction parts is presented in order to enhance the mixing quality in the low Reynolds number regimes for point-of-care tests (POCT). Three classes of micromixers with different numbers of loops and modified geometries were studied. Numerical simulation was performed to study the flow behavior and mixing performance solving the steady-state Navier–Stokes and the convection-diffusion equations in the Reynolds range of 0.1–10.0. Comparisons between the mixers with and without expansion parts were made to illustrate the effect of disturbing the streamlines on the mixing performance. Image analysis of the mixing results from fabricated micromixers was used to verify the results of the simulations. Since the proposed mixer provides up to 92% of homogeneity at Re 1.0, generating 442 Pa of pressure drop, this mixer makes a suitable candidate for research in the POCT field.
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Lotfiani, Amin, and Ghader Rezazadeh. "A new two-layer passive micromixer design based on SAR-vortex principles." International Journal of Chemical Reactor Engineering 19, no. 3 (February 19, 2021): 309–29. http://dx.doi.org/10.1515/ijcre-2020-0222.
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Abstract Micromixers are key components of microfluidic systems for sample analysis, bioreactors, drug delivery, and many other applications. To date, numerous passive micromixer designs have been proposed. Among those, several designs with complex design structures have been demonstrated to be efficient. In the present work, the authors try to propose a new efficient design with low complexity in terms of fabrication. The new design is two-layer and is based on the split and recombination (SAR) and vortex mixing principles. It is suggested to fabricate the new design in polydimethylsiloxane (PDMS) using the soft lithography technique. This new design is chosen among three new designs simulated using the computational fluid dynamics (CFD) software ANSYS Fluent 17.0. The three new designs are named ND1, ND2, and ND3 and their mixing performances are evaluated numerically using mixing index (MI) and mixer effectiveness (ME) quantities at four different Reynolds (Re) numbers in the range of 0.1–100. Calculated values are compared with those obtained for the classical Y-shaped (CY) micromixer. Flow and mixing patterns are computed by solving the continuity, Navier–Stokes, and the convection–diffusion equations. CFD results for the CY micromixer are compared with available experimental and numerical data and reasonable agreement is observed. According to the results, ND3 has the highest performance (ME up to 36.86 percent/mm) among the investigated micromixer designs in the entire range of Re numbers. The maximum pressure drop (35099.9 Pa at Re = 100 for ND3) is still in the range of acceptable pressure drops reported in the literature. ND3 can be used as an efficient substitute for CY. Although ND3 is highly efficient (MI up to 99.52%) at Re numbers lower than 0.3 or higher than 50, its performance at the intermediate Re numbers (0.3 < Re < 50) is poor and unacceptable (MI as low as 44%). This can be simply improved by adding extra mixing units to provide adequate mixing also at the intermediate Re numbers.
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Kim, Noori, Wei Xuan Chan, Sum Huan Ng, Yong-Jin Yoon, and Jont B. Allen. "Understanding Interdependencies between Mechanical Velocity and Electrical Voltage in Electromagnetic Micromixers." Micromachines 11, no. 7 (June 29, 2020): 636. http://dx.doi.org/10.3390/mi11070636.
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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.
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Stanciu, Irina. "Uncertainty Analysis of Mixing Efficiency Variation in Passive Micromixers due to Geometric Tolerances." Modelling and Simulation in Engineering 2015 (2015): 1–8. http://dx.doi.org/10.1155/2015/343087.
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The geometric layout is the key factor for enhancing the efficiency of the fluid mixing in passive micromixers. Therefore, by adjusting the geometric design and by controlling the geometric parameters, one can enhance the mixing process. However, through any fabrication process, the geometric parameters present slight, inherent variation from the designed values than might affect the performance of the micromixer. This paper proposes a numerical study on the influence of the unavoidable geometric tolerances on the mixing efficiency in passive micromixers. A probabilistic simulation model, based on the Monte Carlo method, is developed and implemented for this purpose. An uncertainty simulation model shows that significant deviations from the deterministic design can appear due to small variations in the geometric parameters values and demonstrates how a more realistic mixing performance can be estimated.
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Sabotin, Izidor, Gianluca Tristo, and Joško Valentinčič. "Technical Model of Micro Electrical Discharge Machining (EDM) Milling Suitable for Bottom Grooved Micromixer Design Optimization." Micromachines 11, no. 6 (June 16, 2020): 594. http://dx.doi.org/10.3390/mi11060594.
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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.
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Alijani, Hossein, Arzu Özbey, Mehrdad Karimzadehkhouei, and Ali Koşar. "Inertial Micromixing in Curved Serpentine Micromixers with Different Curve Angles." Fluids 4, no. 4 (December 8, 2019): 204. http://dx.doi.org/10.3390/fluids4040204.
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Micromixers are of considerable significance in many microfluidics system applications, from chemical reactions to biological analysis processes. Passive micromixers, which rely solely on their geometry, have the advantages of low cost and a less-complex fabrication process. Dean vortices seen in curved microchannels are one of the useful tools to enhance micromixing. In this study, the effects of curve angle on micromixing were experimentally investigated in three curved serpentine micromixers consisting of ten segments with curve angles of 180 ° , 230 ° and 280 ° , at Dean numbers between 12 and 87. To characterize and compare the performance of the micromixers, fluorescence intensity maps and mixing indices were utilized. Accordingly, the micromixer having segments with 280 ° curve angle had significantly higher mixing index values up to the Dean number 60 and outperformed the other two micromixers. This was due to the severe distortion of flow streamlines by Dean vortices and the occurrence of chaotic advection at lower Dean numbers. Beyond the Dean number of 70, no difference was observed in the performance of the micromixers and the mixing index at their outlets had the asymptotic value of 0.93 ± 0.02. Furthermore, the flow behavior of the micromixers was numerically simulated to provide further insight about the mixing phenomena.
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Bottausci, Frédéric, Caroline Cardonne, Carl Meinhart, and Igor Mezić. "An ultrashort mixing length micromixer: The shear superposition micromixer." Lab Chip 7, no. 3 (2007): 396–98. http://dx.doi.org/10.1039/b616104a.
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Gong, Youping, Honghao Chen, Wenxin Li, Chuanping Zhou, Rougang Zhou, Haiming Zhao, and Huifeng Shao. "Gradient Printing Alginate Herero Gel Microspheres for Three-Dimensional Cell Culture." Materials 15, no. 6 (March 20, 2022): 2305. http://dx.doi.org/10.3390/ma15062305.
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Hydrogel microspheres are widely used in tissue engineering, such as 3D cell culture and injection therapy, and among which, heterogeneous microspheres are drawing much attention as a promising tool to carry multiple cell types in separated phases. However, it is still a big challenge to fabricate heterogeneous gel microspheres with excellent resolution and different material components in limited sizes. Here, we developed a multi-channel dynamic micromixer, which can use active mechanical mixing to achieve rapid mixing with multi-component materials and extrude the homogenized material. By changing the flow rate ratio of the solutions of the two components and by rapidly mixing in the micromixer, real-time concentration change of the mixed material at the outlet could be monitored in a process so-called “gradient printing”. By studying the mixing efficiency of the micromixer, its size and process parameters were optimized. Using the novel dynamic gradient printing method, the composition of the hydrogel microspheres can be distributed in any proportion and alginate heterogeneous gel microspheres with adjustable cell concentration were fabricated. The effects of cell concentration on cell viability and proliferation ability under three-dimensional culture conditions were also studied. The results showed that cells have very low death rate and can exchange substances within the microspheres. Due to the micromixing ability of the micromixers, the demand for biological reagents and materials such as cells, proteins, cytokines and other materials could be greatly reduced, which helps reduce the experimental cost and improve the feasibility of the method in practical use. The heterogeneous gel microsphere can be greatly valuable for research in various fields such as analytical chemistry, microarray, drug screening, and tissue culture.
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Chen, Xueye, and Xiaolei Wang. "Optimized Modular Design and Experiment for Staggered Herringbone Chaotic Micromixer." International Journal of Chemical Reactor Engineering 13, no. 3 (September 1, 2015): 305–9. http://dx.doi.org/10.1515/ijcre-2014-0123.
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Abstract The staggered herringbone chaotic micromixer has been designed based on the use of modular method and orthogonal experiment. With the modular method, the geometry of the micromixer was divided into straight channels and mixing units alternately. The mixing units were designed with orthogonal experiment. The aspect ratio of the herringbone to the microchannel (r1), the ratio of the width of herringbone to the spacing of between adjacent two herringbones (r2) and the width of the herringbone (r3) were investigated. The optimal outputs were r1 = 1:3, r2 = 1:1, and r3 = 50 µm. The micromixer was fabricated with two steps lithography method based on the presented optimal parameters, and the material of the micromixer was polydimethylsiloxane (PDMS). The optimized design method is proven to be an effective way for rapid design of the staggered herringbone chaotic micromixer.
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Xu, Rui, Shijiao Zhao, Lei Nie, Changsheng Deng, Shaochang Hao, Xingyu Zhao, Jianjun Li, Bing Liu, and Jingtao Ma. "Study on the Technology of Monodisperse Droplets by a High-Throughput and Instant-Mixing Droplet Microfluidic System." Materials 14, no. 5 (March 7, 2021): 1263. http://dx.doi.org/10.3390/ma14051263.
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In this study, we report a novel high-throughput and instant-mixing droplet microfluidic system that can prepare uniformly mixed monodisperse droplets at a flow rate of mL/min designed for rapid mixing between multiple solutions and the preparation of micro-/nanoparticles. The system is composed of a magneton micromixer and a T-junction microfluidic device. The magneton micromixer rapidly mixes multiple solutions uniformly through the rotation of the magneton, and the mixed solution is sheared into monodisperse droplets by the silicone oil in the T-junction microfluidic device. The optimal conditions of the preparation of monodisperse droplets for the system have been found and factors affecting droplet size are analyzed for correlation; for example, the structure of the T-junction microfluidic device, the rotation speed of the magneton, etc. At the same time, through the uniformity of the color of the mixed solution, the mixing performance of the system is quantitatively evaluated. Compared with mainstream micromixers on the market, the system has the best mixing performance. Finally, we used the system to simulate the internal gelation broth preparation of zirconium broth and uranium broth. The results show that the system is expected to realize the preparation of ceramic microspheres at room temperature without cooling by the internal gelation process.
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Podunavac, Ivana, Miroslav Djocos, Marija Vejin, Slobodan Birgermajer, Zoran Pavlovic, Sanja Kojic, Bojan Petrovic, and Vasa Radonic. "3D-Printed Microfluidic Chip for Real-Time Glucose Monitoring in Liquid Analytes." Micromachines 14, no. 3 (February 21, 2023): 503. http://dx.doi.org/10.3390/mi14030503.
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The connection of macrosystems with microsystems for in-line measurements is important in different biotechnological processes as it enables precise and accurate monitoring of process parameters at a small scale, which can provide valuable insights into the process, and ultimately lead to improved process control and optimization. Additionally, it allows continuous monitoring without the need for manual sampling and analysis, leading to more efficient and cost-effective production. In this paper, a 3D printed microfluidic (MF) chip for glucose (Glc) sensing in a liquid analyte is proposed. The chip made in Poly(methyl methacrylate) (PMMA) contains integrated serpentine-based micromixers realized via stereolithography with a slot for USB-like integration of commercial DropSens electrodes. After adjusting the sample’s pH in the first micromixer, small volumes of the sample and enzyme are mixed in the second micromixer and lead to a sensing chamber where the Glc concentration is measured via chronoamperometry. The sensing potential was examined for Glc concentrations in acetate buffer in the range of 0.1–100 mg/mL and afterward tested for Glc sensing in a cell culturing medium. The proposed chip showed great potential for connection with macrosystems, such as bioreactors, for direct in-line monitoring of a quality parameter in a liquid sample.
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Dodge, Arash, Marie-Caroline Jullien, Yi-Kuen Lee, X. Niu, Fridolin Okkels, and Patrick Tabeling. "An example of a chaotic micromixer: the cross-channel micromixer." Comptes Rendus Physique 5, no. 5 (June 2004): 557–63. http://dx.doi.org/10.1016/j.crhy.2004.03.003.
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Noël, Florian, Claire Trocquet, Christophe A. Serra, and Stéphane Le Calvé. "Experimental Validation of a Novel Generator of Gas Mixtures Based on Axial Gas Pulses Coupled to a Micromixer." Micromachines 12, no. 6 (June 18, 2021): 715. http://dx.doi.org/10.3390/mi12060715.
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In this work, a novel generator of gas mixtures previously numerically investigated and based on axial gas pulses coupled to a micromixer has been conceived, manufactured, and validated. Standard gaseous pollutant mixtures and pure nitrogen or pure air were introduced in a microdevice designed to generate alternating axial gas pulses which were downstream homogenized by means of a multi-stage modular micromixer. The dilution, and therefore the final pollutant concentration, was controlled by two parameters: the ratio between the times of each of the two gas pulses and the partial pressure of the pollutant(s) mixture added to the device. The gas mixture generator was coupled to an analyzer to monitor the concentration of aromatic pollutants. The response time was optimized to be lower than 2 min in accordance with the analytical instrument. The quantity of pollutants measured at the micromixer’s outlet increased linearly with the expected gas concentration of 3.7–100 ppb generated by this novel microfluidic generator and fitted perfectly with those obtained by a reference gas dilution bench. At 5 ppb, the precision on the concentration generated is close to that obtained with the conventional gas mixing bench, i.e., around 10%.
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Wang, Chin-Tsan, Yan-Ming Chen, and Shih-Syun Chen. "Heart-Like Micro-Flow Mixer." International Journal of Chemical Reactor Engineering 14, no. 1 (February 1, 2016): 343–49. http://dx.doi.org/10.1515/ijcre-2014-0181.
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AbstractMicromixers are the microfluidic devices able to rapidly mix more than two liquids, with low pressure drop and high mixing efficiency (εmixing). In this study, the effect of Reynolds number ratio (Rer) and aspect ratio (AR) of heart-like biometric micromixer applied would be investigated by a numerical simulation and experimental confirmation. Results show that the heart-like biometric micromixer resulting from the coupling effect of the split and recombination (SAR) and biometric design can produce a high mixing efficiency, low pressure drop and short mixing path under a case of low Reynolds number. Two dimensional results also find that a flow mixing efficiency of εmixing=0.89 and an optimal mixing index of Midx=115 could be achieved at a flow condition of Rer=0.75 and Re2=0.1 of the middle-inlet channel I2. In additional, the three dimensional results indicate that a high flow mixing efficiency of εmixing=0.84 and the lowest pressure drop of 164.2 Pa was obtained at the flow conditions of Rer=0.9 and AR=10 when the middle-inlet channel I2 was Re2=0.1. These findings will be useful to improvement the efficiency for micromixcers of biometric design in the future.
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Stakhiv, Volodymyr, Oleh Matviykiv, Tamara Klymkovych, and Vitalii Pidtserkovnyi. "MODELING AND RESEARCH OF ACTIVE ROTARY MICROMIXER FOR MICROFLUID DEVICES." Computer Design Systems. Theory and Practice 3, no. 1 (December 28, 2021): 55–60. http://dx.doi.org/10.23939/cds2021.01.055.
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The article develops a laboratory design for mixing substances of three types and a model of active micromixer. The mixing of the particles of the angular velocities of the micromixer is investigated.
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Shen, Hongying, and Guowei Wang. "A versatile flash cyclization technique assisted by microreactor." Polymer Chemistry 8, no. 36 (2017): 5554–60. http://dx.doi.org/10.1039/c7py01034f.
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An innovative and versatile flash cyclization technique assisted by microreactor (or micromixer) is presented. The cyclization of linear poly(ethylene oxide) (l-PEO) with high efficiency can be instantly and completely realized in a micromixer.
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Minakov, Andrey V., Alexander S. Lobasov, Anna A. Shebeleva, and Alexander V. Shebelev. "Analysis of Hydraulic Mixing Efficiency in Widespread Models of Micromixers." Fluids 5, no. 4 (November 18, 2020): 211. http://dx.doi.org/10.3390/fluids5040211.
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In this paper, we present the results of a systematic numerical study of the flow and mixing modes of fluids in micromixers of various configurations, in particular, an analysis of passive micromixers, the most widely used in practice, as well as the main methods to intensify mixing. The advantages of microstructure reactors can significantly reduce reaction times and increase productivity compared to traditional bulk reactors. Four different geometries of micromixers, including the straight T-shaped microchannel, were considered. The effect of the geometrical patterns of micromixers, as well as of the Reynolds number on flow regimes and mixing efficiency were analyzed. The Reynolds number varied from 1 to 300. Unlike other studies, the efficiency of the considered mixers was for the first time compared with the cost of pressure loss during pumping. As a result, the efficiency of the most optimal micromixer in terms of hydraulic mixing and the optimal operation ranges were determined. It was shown that the maximum normalized mixing efficiency in the entire range of Re numbers was noted for mixer, in which a vortex-based intensification of mixing occurs due to the flow swirling in cylindrical chambers. This mixer allows mixing the fluids 600 times more efficiently than a straight T-mixer, while all other conditions being equal.
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Bahadorimehr, Ali Reza, Mitra Damghanian, and Majlis Burhanuddin Yeop. "A Static Micromixer Inspired from Fractal-Like Natural Flow Systems." Advanced Materials Research 254 (May 2011): 25–28. http://dx.doi.org/10.4028/www.scientific.net/amr.254.25.
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A static micromixer having a fractal-like structure is proposed inspired from natural flow networks. The mixing behavior of flow in this micromixer is investigated using numerical and experimental approaches. This converging flow network is basically using the mechanisms of fluid multilamination for mixing enhancement. Simulations are made on the flow behavior to investigate the effect of branching numbers, hierarchy levels, geometrical sizes and other design parameters using FEM methods. A rapid prototyping system for microfluidics using PDMS molding technology was successfully utilized to fabricate the designed multichannel micromixer. Experimentally, image processing technique was used to characterize flow and mixing quality in the microfluidic structure. Obtained results from numerical simulation and experimental measurements are compared with a single channel with equal flow length using the mixing quality index. This improved micromixer can further be optimized in terms of fractal shapes and numbers and geometrical size for specific applications.
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XIONG, SIYUE, and XUEYE CHEN. "NUMERICAL SIMULATION OF THREE-DIMENSIONAL PASSIVE MICROMIXER WITH VARIABLE-ANGLE GROOVES AND BAFFLES." Surface Review and Letters 28, no. 05 (March 22, 2021): 2150037. http://dx.doi.org/10.1142/s0218625x21500372.
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In this paper, we have studied the effect of variable-angle grooves and baffles on the mixing efficiency of the micromixer. In order to explore the influence on the micromixer with different types of grooves and baffles, we designed grooves and baffles with different geometric parameters and placed them in T-channels to interfere with fluid flow. We studied VAM30∘ (variable-angle grooves and baffles micromixer with an angle of 30∘) directions and distributions as well as their different groove depths and baffle heights affect the mixing performance. We tried to divide the grooves and baffles into five groups, and discussed the effects of staggered depth and height on mixing efficiency. The mixing efficiencies of micromixer in the Re (Reynolds number) range of 0.1–100 were calculated, and the fluid flow in the microchannel was analyzed. The simulation results show that VAM30∘ is more favorable for solution mixing. The mixing efficiency of the micromixer could reach 98.9% with the change of different geometric parameters. This is because when the structure changes, the flow state of the fluid is improved, which is conducive to lengthening the residence time of the fluid in the channel. With the increase of Re, it is also conducive to enhancing the chaotic convection and improving the mixing efficiency.
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Naas, Toufik Tayeb, Shakhawat Hossain, Muhammad Aslam, Arifur Rahman, A. S. M. Hoque, Kwang-Yong Kim, and S. M. Riazul Islam. "Kinematic Measurements of Novel Chaotic Micromixers to Enhance Mixing Performances at Low Reynolds Numbers: Comparative Study." Micromachines 12, no. 4 (March 28, 2021): 364. http://dx.doi.org/10.3390/mi12040364.
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In this work, a comparative investigation of chaotic flow behavior inside multi-layer crossing channels was numerically carried out to select suitable micromixers. New micromixers were proposed and compared with an efficient passive mixer called a Two-Layer Crossing Channel Micromixer (TLCCM), which was investigated recently. The computational evaluation was a concern to the mixing enhancement and kinematic measurements, such as vorticity, deformation, stretching, and folding rates for various low Reynolds number regimes. The 3D continuity, momentum, and species transport equations were solved by a Fluent ANSYS CFD code. For various cases of fluid regimes (0.1 to 25 values of Reynolds number), the new configuration displayed a mixing enhancement of 40%–60% relative to that obtained in the older TLCCM in terms of kinematic measurement, which was studied recently. The results revealed that all proposed micromixers have a strong secondary flow, which significantly enhances the fluid kinematic performances at low Reynolds numbers. The visualization of mass fraction and path-lines presents that the TLCCM configuration is inefficient at low Reynolds numbers, while the new designs exhibit rapid mixing with lower pressure losses. Thus, it can be used to enhance the homogenization in several microfluidic systems.
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Xiong, Siyue, and Xueye Chen. "Numerical simulation of three-dimensional passive micromixer based on the principle of Koch fractal." International Journal of Chemical Reactor Engineering 19, no. 5 (March 25, 2021): 465–72. http://dx.doi.org/10.1515/ijcre-2021-0020.
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Abstract In this paper, We arrange the obstacles based on the Koch fractal principle (OKF) in the micromixer. By changing the fluid flow and folding the fluid, a better mixing performance is achieved. We improve the mixing efficiency by placing OKF and changing the position of OKF, then we studied the influence of the number of OKF and the height of the micromixer on the mixing performance. The results show that when eight OKF are staggered in the microchannel and the height is 0.2 mm, the mixing efficiency of the OKF micromixer can reach 97.1%. Finally, we compared the velocity cross section and velocity streamline of the fluid, and analyzed the influence of OKF on the concentration trend. Through analysis, it is concluded that OKF can generate chaotic convection in the fluid, and enhance the mixing of fluids by generating vortices and folding the fluid. It can effectively improve the mixing efficiency of the micromixer.