CFD analysis and RSM-based design optimization of novel grooved micromixers with obstructions

Rahmannezhad, Javad; Mirbozorgi, Seyed Ali

doi:10.1016/j.ijheatmasstransfer.2019.05.107

Cited by 62 publications

(18 citation statements)

References 23 publications

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“…The results of the present study are very promising when compared to other related studies using complex on-chip structures for mixing procedures [ 15 , 23 , 24 , 25 , 26 , 27 , 28 , 29 ]. In some of these studies, external microelectrodes were used and integrated on the chip to generate frequency switching transverse EOF for chaotic mixing [ 15 , 24 ].…”

Section: Discussionsupporting

confidence: 58%

Fundamental Studies of Rapidly Fabricated On-Chip Passive Micromixer for Modular Microfluidics

et al. 2021

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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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Section: Discussionsupporting

confidence: 58%

Fundamental Studies of Rapidly Fabricated On-Chip Passive Micromixer for Modular Microfluidics

et al. 2021

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“…In order to quantitatively analyze the diffusion rate of species and the extent of mixing at a certain plane, two essential paraments were adopted, namely the dispersion length [ 35 ] and the mixing index [ 7 ]. As shown in Figure 3 , the definition of dispersion length is the distance from the contact point of two liquids to the place where the mass fraction of downstream central sample solution is less than 1.…”

Section: Objectives Model Structure and Numerical Methodologymentioning

confidence: 99%

“…It is known that the mixing of reagents should be done quickly before obvious chemical reaction progress occurs. However, the flow in the microchannel remains laminar and the mass transport process depends mainly on molecular diffusion [ 7 ]. Therefore, it is difficult to obtain a uniformly mixed microfluid [ 8 ].…”

Section: Introductionmentioning

confidence: 99%

An Investigation of Flow Patterns and Mixing Characteristics in a Cross-Shaped Micromixer within the Laminar Regime

et al. 2021

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A fast mixing is critical for subsequent practical development of microfluidic devices, which are often used for assays in the detection of reagents and samples. The present work sets up computational fluid dynamics simulations to explore the flow characteristic and mixing mechanism of fluids in cross-shaped mixers within the laminar regime. First, the effects of increasing an operating parameter on local mixing quality along the microchannels are investigated. It is found that sufficient diffusion cannot occur even though the concentration gradient is large at a high Reynolds number. Meanwhile, a method for calculating local mixing efficiency is also characterized. The mixing efficiency varies exponentially with the flow distance. Second, in order to optimize the cross-shaped mixer, the effects of design parameters, namely aspect ratio, mixing angle and blockage, on mixing quality are captured and the visualization of velocity and concentration distribution are demonstrated. The results show that the aspect ratio and the blockage play an important role in accelerating the mixing process. They can improve the mixing efficiency by increasing the mass transfer area and enhancing the chaotic advection, respectively. In contrast, the inflow angle that affects dispersion length is not an effective parameter. Besides, the surface roughness, which makes the disturbance of fluid flow by roughness more obvious, is considered. Three types of rough elements bring benefits for enhancing mixing quality due to the convection induced by the lateral velocity.

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“…This technique is dependent on the generation of eddies or turbulence [32], but in low Reynolds numbers this is hindered (48% mixing efficiency [33]). An example of obstacles placed in a microfluidic channel is seen in Figure 1d, but the mixing performance varies with obstacle shape [34].…”

Section: Micromixing Methodsmentioning

confidence: 99%

Microfluidic Magnetic Mixing at Low Reynolds Numbers and in Stagnant Fluids

et al. 2019

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Microfluidic mixing becomes a necessity when thorough sample homogenization is required in small volumes of fluid, such as in lab-on-a-chip devices. For example, efficient mixing is extraordinarily challenging in capillary-filling microfluidic devices and in microchambers with stagnant fluids. To address this issue, specifically designed geometrical features can enhance the effect of diffusion and provide efficient mixing by inducing chaotic fluid flow. This scheme is known as “passive” mixing. In addition, when rapid and global mixing is essential, “active” mixing can be applied by exploiting an external source. In particular, magnetic mixing (where a magnetic field acts to stimulate mixing) shows great potential for high mixing efficiency. This method generally involves magnetic beads and external (or integrated) magnets for the creation of chaotic motion in the device. However, there is still plenty of room for exploiting the potential of magnetic beads for mixing applications. Therefore, this review article focuses on the advantages of magnetic bead mixing along with recommendations on improving mixing in low Reynolds number flows (Re ≤ 1) and in stagnant fluids.

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CFD analysis and RSM-based design optimization of novel grooved micromixers with obstructions

Cited by 62 publications

References 23 publications

Fundamental Studies of Rapidly Fabricated On-Chip Passive Micromixer for Modular Microfluidics

Fundamental Studies of Rapidly Fabricated On-Chip Passive Micromixer for Modular Microfluidics

An Investigation of Flow Patterns and Mixing Characteristics in a Cross-Shaped Micromixer within the Laminar Regime

Microfluidic Magnetic Mixing at Low Reynolds Numbers and in Stagnant Fluids

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