Chaotic Micromixer Research Articles

Design, Implementation, and Optimization of a Novel Chaotic Micromixer

Design, Implementation, and Optimization of a Novel Chaotic Micromixer

Thermal and Hydrodynamic Measurements of a Novel Chaotic Micromixer to Enhance Mixing Performance

In this study, three-dimensional simulations were conducted on a new passive micromixer to assess the thermal and hydrodynamic behaviors of Newtonian and non-Newtonian fluids subjected to low generalized Reynolds numbers (0.1 to 50) and shear-thinning properties. To acquire a more profound comprehension of the qualitative and quantitative fluctuations in fluid fraction using the CFD Fluent Code, the mass mixing index, rheological behavior, performance index, mixing energy cost, mass fraction distributions, temperature contours, and pressure drop were compared to illustrate the importance of the mixer geometry in the context of two miscible fluids with varying inlet temperatures. The selected geometry is characterized by a robust chaotic flow that substantially enhances thermal and hydrodynamic performance across all Reynolds numbers. A mass mixing exceeding 72.5% is obtained when Re = 5, reaching 93.5% when Re = 50. Furthermore, the evolution of thermal mixing for all behavior indexes reaches a step of 98% with minimal pressure losses. This work enabled the demonstration of a chaotic geometry in a highly efficient mixing system, leading to enhanced thermal performance for both Newtonian and non-Newtonian fluids. The results of the hydrodynamic and thermal characterization of the mixing of shear-thinning fluids within the micromixers under investigation are conclusive.

Numerical investigation of induction of chaotic micromixing via vibration switching

Enhanced mixing in microfluidic systems is necessary in many applications such as chemical processing, biological assays, and diagnosis. We are developing a microfluidic system to efficiently mix minute reagents (down to several microliters) using vibration-induced flow (VIF), in which a net flow is generated around a micropillar by applying periodic vibration. In this study, we numerically investigate the enhancement in chaotic mixing using the VIF technique and periodic switching of vibrations. By extending our previous numerical simulation model, we investigate the flow field and trajectories of fluid particles in three-dimensional space. We demonstrate that chaotic advection characteristics can be observed by periodically switching the vibrational direction of a substrate using simple cylindrical pillars. In addition, using an appropriate interval for switching the vibration axes yields better mixing performance. The extent of chaotic advection is evaluated quantitatively using the Lyapunov exponent considering various vibration parameters, such as the vibration amplitude, separation distance between each pillar and pillar shape. The flow field induced by a large-amplitude and sharp-edged wall pillar provides excellent mixing results. Thus, VIF is successfully applied to obtain an efficient mixing strategy with the aid of the chaotic theory.

Numerical Investigation on a Chaotic Passive Micromixer Based on Square Chambers Connected with Different Channel Shapes for Enhancing the Mixing Process

Numerical Investigation on a Chaotic Passive Micromixer Based on Square Chambers Connected with Different Channel Shapes for Enhancing the Mixing Process

Rapid Diagnosis of Urinary Tract Cancers on a LEGO-Inspired Detection Platform via Chemiresistive Profiling of Volatile Metabolites.

Rapid and in situ profiling of volatile metabolites from body fluids represents a new trend in cancer diagnosis and classification in the early stages. We report herein an on-chip strategy that combines an array of conductive nanosensors with a chaotic gas micromixer for real-time monitoring of volatiles from urine and for accurate diagnosis and classification of urinary tract cancers. By integrating a class of LEGO-inspired microchambers immobilized with MXene-based sensing nanofilms and zigzag microfluidic gas channels, it enables the intensive intermingling of volatile organic chemicals with sensor elements that tremendously facilitate their ion-dipole interactions for molecular recognition. Aided with an all-in-one, point-of-care platform and an effective machine-learning algorithm, healthy or diseased samples from subpopulations (i.e., tumor subtypes, staging, lymph node metastasis, and distant metastasis) of urinary tract cancers can be reliably fingerprinted in a few minutes with high sensitivity and specificity. The developed detection platform has proven to be a noninvasive supplement to the liquid biopsies available for facile screening of urinary tract cancers, which holds great potential for large-scale personalized healthcare in low-resource areas.

Mixing Enhancement in a Chaotic Micromixer with Reversed Ridges and Grooves

Mixing Enhancement in a Chaotic Micromixer with Reversed Ridges and Grooves

Evolution of Entropy Generation on Mixing Process Using a Novel Chaotic Micromixer

This study aims to compare numerically the laminar steady flow of shear-thinning non Newtonian fluids in novel chaotic micromixer. The process is verified for non-Newtonian flow in a complex geometry that is heated with a constant flux. The selected geometry produce secondary flow structures that greatly improve fluid dynamic performance. To measure this performance, the Poincaré map method is used for various cases of fluid power-law index in different geometries. In addition, thermal mixing behavior is studied for shear-thinning fluids in the chosen geometry with two different inlet temperatures.In different cases of fluid power-law indexes, the novel geometry resulted in an 82% increase in thermal mixing degree relative to the thermal mixing degree observed in the C-shaped and serpentine channels. The second law of thermodynamics is examined in terms of entropy generation caused by thermal and hydrodynamic processes, as a function of low rates of generalized Reynolds number and power-law index, while taking into consideration the effects of chaotic advection. As a result, the new configuration showed a significant improvement in the degree of mixing compared to other geometries considered, while also minimizing friction and thermal irreversibilities.

Heat transfer behaviour of mixing nano-non-Newtonian fluid in a chaotic micromixer

The hydrodynamic and thermal behaviors of Nano-Non-Newtonian fluids were examined using three-dimensional numerical simulations of a unique passive micromixer. To comprehend the quantitative and qualitative fluid fraction distributions with temperature homogenization, mass and heat transport properties of two heated fluids have been examined. For varied Reynolds numbers, the influence of fluid behavior and various Al2O3 nanoparticle concentrations on the pressure drop and thermal mixing capabilities were examined. Using CFD, the simulation of performance enhancement was run in intervals of varying Nanoparticle concentrations with Power-law index (n). In terms of fluid homogenization, the proposed micromixer demonstrated a mixing energy cost of 60% comparable to that realized for a recent micromixer (2021y). According to the analysis, for high nanofluid.

Statistical Image Analysis on Liquid-Liquid Mixing Uniformity of Micro-Scale Pipeline with Chaotic Structure

The aim of this work is to introduce a novel statistical technique for quantifying the concentration field uniformity of the liquid-liquid mixing process within a micro-scale chaotic pipeline. For illustration, the microscale liquid-liquid mixer in which the inlet direction is parallel to the mixing unit is designed by using the chaotic pipeline with Baker map. Meanwhile, the non-uniformity coefficient method is adopted quantificationally instead of qualitatively estimating the concentration field uniformity of the chaotic micromixer based on uniform design theory and image analysis. Results show that the concentration distribution of the chaotic mixing process of liquid-liquid under various working conditions is obtained by solving the steady-state Navier–Stokes and diffusion convection equations. The average contribution ratio of the three basic mixing units of the chaotic Baker pipeline to the concentration field uniformity is approximately 6:3:1, which is calculated aligned with the fluid flow direction successively. The optimal mixing uniformity can be obtained as the initial velocity is 0.05 m/s and the diffusion coefficient is 5 × 10−9 m2/s, respectively. The reliability of the new method for estimating the concentration field uniformity parameters is explained from three dimensions. The statistical image analysis technique is illustrated to be reliable and effective in yielding accurate concentration field information of the simulated chaotic mixer. Furthermore, it can be adapted to examine a variety of concentration distribution issues in which concentrations are evaluated under distinct scales.

Design and analysis of a novel Bi-layer curved serpentine chaotic micromixer for efficient mixing

Mixing enhancement at the micro-scale is important in microfluidics applications, including biological and chemical analysis systems. Herein, two new designs of chaotic micromixers named Bi-layer Curved Serpentine (BCS1 and BCS2) micromixers were proposed. The performance analyses were performed by solving the steady equations of conservation of mass and momentum along with the convection-diffusion equation numerically at Reynolds numbers of 0.1–200. These micromixers consisted of curved serpentine channels stacked in two layers with different combinations of curved channel radii in each layer. They exhibited efficient homogenization with a comparatively lower pressure drop and a higher mixing cost. The main mixing processes were Dean vortices, extensional flow, and chaotic advection caused by asymmetrical vortices. The BCS1 micromixer, which has a constant but unequal radius of the serpentine channel in the top and bottom layers, showed the best mixing. BCS1 and BCS2 micromixers showed significantly higher mixing indices than the simple serpentine (SS) micromixer. Furthermore, the BCS1 micromixer provided a higher mixing cost by showing similar mixing at a ∼53% lesser pressure drop than a previously proposed serpentine micromixer. BCS1 and BCS2 micromixers showed mixing index values higher than 0.80 at Re ≥ 40 and Re ≥ 60, respectively.

Evaluation of Hydrodynamic and Thermal Behaviour of Non-Newtonian-Nanofluid Mixing in a Chaotic Micromixer.

Three-dimensional numerical investigations of a novel passive micromixer were carried out to analyze the hydrodynamic and thermal behaviors of Nano-Non-Newtonian fluids. Mass and heat transfer characteristics of two heated fluids have been investigated to understand the quantitative and qualitative fluid faction distributions with temperature homogenization. The effect of fluid behavior and different Al2O3 nanoparticles concentrations on the pressure drop and thermal mixing performances were studied for different Reynolds number (from 0.1 to 25). The performance improvement simulation was conducted in intervals of various Nanoparticles concentrations (φ = 0 to 5%) with Power-law index (n) using CFD. The proposed micromixer displayed a mixing energy cost of 50–60 comparable to that achieved for a recent micromixer (2021y) in terms of fluid homogenization. The analysis exhibited that for high nanofluid concentrations, having a strong chaotic flow enhances significantly the hydrodynamic and thermal performances for all Reynolds numbers. The visualization of vortex core region of mass fraction and path lines presents that the proposed design exhibits a rapid thermal mixing rate that tends to 0.99%, and a mass fraction mixing rate of more than 0.93% with very low pressure losses, thus the proposed micromixer can be utilized to enhance homogenization in different Nano-Non-Newtonian mechanism with minimum energy.

Performance optimization of chaotic flow micromixer

Performance optimization of chaotic flow micromixer

Design and Evaluation of Three-Dimensional Zigzag Chaotic Micromixers for Biochemical Applications

Design and Evaluation of Three-Dimensional Zigzag Chaotic Micromixers for Biochemical Applications

Kinematic Measurements of Novel Chaotic Micromixers to Enhance Mixing Performances at Low Reynolds Numbers: Comparative Study.

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.

High hydrodynamic and thermal mixing performances of efficient chaotic micromixers: A comparative study

Efficient micromixers are largely used in different industrial applications. The mixing in laminar regime at low Reynolds numbers has a major significance in some processes. Exploiting the physical phenomenon of chaotic advection to improve the mixing efficiency is a well-established technique. This work consists in studying numerically the influence of the micromixers geometry on the hydrodynamic and thermal mixing performances using different configurations, which are respectively: TLCCM with an aspect ratio of l/W = 1, L-Shape, OH, and OX. All micromixer geometries have the same hydraulic diameter and an equivalent length. The numerical simulations were performed with low Reynolds numbers (0.2 – 70). Navier-Stokes equations were solved numerically using a commercial CFD software (ANSYS Fluent). Thus, the model adopted to characterize the mixing is the species transport model. To analyze the obtained results, the mass fraction contours, the velocity vectors and profiles, the temperature contours, the friction coefficient and the mixing energy cost were presented. The results show that the proposed micromixer has the best mixing performance with a mixing index that reaches to 0.99, and thermal mixing index more than 0.932 at very low Reynolds numbers, it also has the lowest mixing energy cost compared to that obtained in previous works.

Microreaction system combining chaotic micromixing with fast mixing and particle growth in liquid-segmented flow for the synthesis of hazardous ionic materials

A microreaction system, which combines chaotic mixing with liquid-segmented flow for the synthesis of hazardous ionic materials, was established. Previous single micro-segmented flow achieved good mixing by increasing the length of the tube via the slow diffusion of the reactants; however, it consumed a long residence time and achieved a low efficiency. Consequently, optimized chaotic micromixing was applied to achieve rapid and excellent initial mixing of the reactants. Thereafter, the optimized chaotic micromixing was combined with the liquid-segmented flow to ensure the homogeneity of particle nucleation/growth while overcoming encrustation challenges. Two tubing coils were employed for the crystal nucleation and growth; they extensively reduced the size of the microreaction system. Additionally, a separation column was designed to achieve on-line recovery of the carrier fluid, followed by on-line separation of the products and waste. Furthermore, the initial performance and design evaluation of the microreaction system were performed. Furthermore, we utilized typical ionic primary explosives, barium-2,4,6-trinitroresorcinate (BaTNR) and lead-2,4,6-trinitroresorcinate styphnate (LTNR), to verify the applicability of the microreaction system. Further, BaTNR and LTNR particles with better crystal morphologies, narrower size distributions, and higher heat release than those of the single micro-segmented flow were prepared to illustrate the advantages of the system. The particle size of BaTNR synthesized by the microreaction system ranged from 5 to 13 ​μm, while the heat release was 168.7 ​J·g−1 greater than that of BaTNR prepared by the micro-segmented flow platform. The particle size of LTNR ranged from 30 to 90 ​μm, while the heat release was 230.1 ​J·g−1 greater than that of LTNR prepared by the micro-segmented flow platform. Conclusively, this study demonstrated the feasibility of an efficient and safe microreaction system for synthesizing hazardous ionic materials.

Mixing efficiency enhancement by a modified curved micromixer: A numerical study

The flow characteristics and mixing efficiency in a novel chaotic micromixer is numerically investigated from both eulerian and lagrangian viewpoints. The configuration consists of four successive quadrant units organized in a non-planar arrangement. A scalar equation is solved alongside conversation equations to determine the concentration of dye species. The effect of Reynolds number and aspect ratio on velocity field and streamlines, mixing index, pressure drop, mixing performance, energy efficiency factor and entropy generation are evaluated and some comparisons are made against a simple curved micromixer. The results reveal that the chaotic configuration is responsible for generating unsymmetrical transverse flows throughout the micomixer. The modified curved micromixer can enhance mixing index 0–2.04 times at the cost of increment of pressure drop by only 0–1.23 times in comparison with those values of simple curved micromixer. The existence of an optimum Reynolds number in maximizing the energy efficiency factor of chaotic micro configuration is established. The chaotic advection plays more important role on mixing efficiency in narrower configurations. Our simulated findings disclose that the present chaotic micromixer is more efficient in chemical applications, in which a rapid mixing is required in micro scale, compared to conventional T-type those.

Numerical and Experimental Study on Mixing in Chaotic Micromixers with Crossing Structures

AbstractTwo chaotic micromixers (Models A and B) based on the split‐and‐recombine principle using multilayer microchannels are proposed and the mixing performance was analyzed numerically and experimentally for a wide range of Reynolds numbers. The fluid flow and mixing performance were numerically analyzed by solving Navier‐Stokes equations. Micromixers were fabricated using a soft‐lithography technique. As working fluids, water and a dye/water mixture were used. Quantitative and qualitative analyses were performed using confocal scanning microscopy and image processing techniques. The micromixers could enhance the mixing performance by expanding the interfaces between the working fluids to be mixed. The results confirm the superior mixing index of Model B compared to that of Model A.

Nanomechanical Microfluidic Mixing and Rapid Labeling of Silica Nanoparticles using Allenamide-Thiol Covalent Linkage for Bioimaging.

Rapid surface functionalization of nanomaterials using covalent linkage following "green chemistry" remains challenging, and the quest for developing simple protocols is persisting. We report a nanomechanical microfluidic approach for the coupling of allenamide functionalized organic derivatives on the surface of thiol-modified silica nanoparticles using allenamide-thiol chemistry. The coupling principle involves the use of a microfluidic surface acoustic wave device that generates acoustic streaming-based chaotic fluid micromixing that enables mixing of laterally flowing fluids containing active components. This approach was used to demonstrate the direct surface labeling of thiol-modified silica nanoparticles using a selected group of modified fluorescent tags containing allenamide handles and achieved a total labelingefficiency of 83-90%. This green approach enabled a highly efficient surface functionalization under aqueous conditions, with tunable control over the conjugation process via the applied field. The dye-labeled silica particles were characterized using various analytical techniques and found to be biocompatible with potential in live cell bioimaging. It is envisaged that this bioconjugation strategy will find numerous applications in the field of bioimaging and drug delivery.

High-Precision Stereolithography of Biomicrofluidic Devices.

Stereolithography (SL) is emerging as an attractive alternative to soft lithography for fabricating microfluidic devices due to its low cost and high design efficiency. Low molecular weight poly(ethylene glycol)diacrylate (MW = 258) (PEG-DA-258) has been used for SL 3D-printing of biocompatible microdevices at submillimeter resolution. However, 3D-printing resins that simultaneously feature high transparency, high biocompatibility, and high resolution are still lacking. It is found that photosensitizer isopropyl thioxanthone can, in a concentration-dependent manner, increase the absorbance of the resin (containing PEG-DA-258 and photoinitator Irgacure-819) by over an order of magnitude. This increase in absorbance allows for SL printing of microdevices at sub pixel resolution with commercially available desktop printers and without compromising transparency or biocompatibility. The assembly-free, rapid (<15 h) 3D-printing of a variety of complex 3D microfluidic devices such as a 3D-fluid router, a passive chaotic micro-mixer, an active micro-mixer with pneumatic microvalves, and high-aspect ratio (37:1) microchannels of single pixel width is demonstrated. These manufacturing capabilities are unavailable in conventional microfluidic rapid prototyping techniques. The low absorption of small hydrophobic molecules and microfluidic labeling of cultured mammalian cells in 3D-printed PEG-DA-258 microdevices is demonstrated, indicating the potential of PEG-DA-based fabrication of cell-based assays, drug discovery, and organ-on-chip platforms.