Taming Taylor-Aris dispersion through chaotic advection

Biagioni, Valentina; Venditti, Claudia; Adrover, Alessandra; Giona, Massimiliano; Cerbelli, Stefano

doi:10.1016/j.chroma.2022.463110

Cited by 11 publications

(9 citation statements)

References 43 publications

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“…The optimal velocity lies around 100 μm s –1 (see the dashed line) due to the small molecular diffusion coefficient ( D m = 80 μm 2 s –1 ) of the studied molecule (FITC–Dextran 20 kDa). In a recent theoretical study of Cerbelli and co-workers, it was demonstrated that the region near the conventionally observed minimum of the van Deemter curve is in fact more complex in the vortex chromatography mode, displaying near the minimum two inflection points. The exact curve shape is very likely to depend on the vortex flow profile, which is most likely not identical for the conducted theoretical work as compared to the experimental work presented here.…”

Section: Resultsmentioning

confidence: 97%

“…Because of the limited options to further exploit the reduction of the characteristic dimensions of flow-through channels, a methodology to introduce a nongeometrical approach to increase lateral mass transport was recently pursued by our group . Also, the theoretical work of other groups , convincingly showed the favorable impact of lateral flow on dispersion under retained and unretained conditions. Very recently, a simulation study also predicted a large performance gain when enhancing lateral transport of particles (with an inherently small molecular diffusion coefficient) in the context of hydrodynamic chromatography, with an analysis time gain of a factor of 50, resulting from the induced lateral flow (particle mixture with dimensionless radii of 1:20, 1:40, and 1:80) .…”

Section: Introductionmentioning

confidence: 99%

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C-Term Reduction in 3 μm Open-Tubular High-Aspect-Ratio Channels in AC-EOF Vortex Chromatography Operation

et al. 2023

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The performance of liquid chromatography operation in open-tubular channels, the ideal chromatographic column format, is limited by slow mass transport between the mobile and stationary phase. We recently introduced a lateral mixing methodology (“vortex chromatography”) to reduce Taylor–Aris dispersion by employing (small) AC-EOF (alternating current electroosmotic flow) fields oriented perpendicular to the conventionally applied, axially oriented pressure gradient, resulting in the reduction of the C-term by a factor of 3, studied in 40 × 20 μm2 (aspect ratio (AR) = 2) channels under unretained conditions. In the present contribution, a further increased performance gain for channel dimensions relevant for chromatographic applications is demonstrated. The impact of the applied voltage and salt concentration is studied for 3 × 20 and 5 × 20 μm2 channels in ARs of up to 6.7, revealing a C-term reduction potential of a factor of up to 5 for large molecules (dextran) under unretained conditions. The decrease in κaris in a 5 μm channel (reduction of 80%) was larger than the decrease in a 3 μm channel (reduction of 44%).

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Section: Resultsmentioning

confidence: 97%

Section: Introductionmentioning

confidence: 99%

C-Term Reduction in 3 μm Open-Tubular High-Aspect-Ratio Channels in AC-EOF Vortex Chromatography Operation

et al. 2023

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“…Using an extended version of the classic Taylor–Aris theory, − an analytical expression could be derived for the plate height H in a binary capillary system with DB H = H 1 + H σ H 1 = 2 D mol u 0 + 1 210 10.72 + 35.47 k ″ + 26.49 k false″ 2 false( 1 + k ″ false) 2 u 0 d normalm 2 D normalm + 1 6 k false″ 2 false( 1 + k false″ false) 2 u 0 d normals 2 D normals H σ = σ 2 1…”

Section: Introductionmentioning

confidence: 99%

“…Using an extended version of the classic Taylor–Aris theory, − an analytical expression could be derived for the plate height H in a binary capillary system with DB wherein H 1 represents the dispersion in a single capillary and H σ represents the excess plate height created by the polydispersity effect under DB conditions. k ″ is the so-called zone-retention factor (time spent in porous walls versus time spent in the flowing zone), d m is the characteristic size (=hydrodynamic diameter) of the flow-through channels (m), D m is the diffusion coefficient in the mobile phase (m 2 /s), d s is the thickness of the stationary phase separating the flow-through channels (m), D s is the diffusion coefficient in the stationary phase (m 2 /s), and σ is the relative standard deviation of the flow-through channels.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic Validation of the Diffusional Bridging Effect Suppressing Dispersion in Multicapillary Flow Systems

Vankeerberghen

Parmentier²,

Desmet

2023

Anal. Chem.

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The efficiency of liquid chromatography separations could be strongly improved by changing the current packed bed columns by a bundle of parallel capillary tubes. In practice, however, the polydispersity effect, which emanates from the inevitable small differences in capillary diameter, completely ruins this potential. The concept of diffusional bridging, introducing a diffusive cross talk between adjacent capillaries, has recently been proposed to resolve this. The present contribution provides the first experimental proof for this concept and quantitatively validates its underlying theory. This has been accomplished by measuring the dispersion of a fluorescent tracer in 8 different microfluidic channels with different degrees of polydispersity and diffusional bridging. The observed degree of dispersion reduction agrees very well with the theoretical predictions, hence opening the road to the use of this theory to design a new family of chromatographic beds, potentially offering unprecedented performance.

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“…In a microfluidic channel with oxide-insulated electrodes, the experimental investigation by Westerbeek et al showed that the ACET greatly reduces (by almost three times) the Taylor–Aris dispersion compared to the no-mixing condition. In addition, it has been shown that the three-dimensional (3D) chaotic streamlines produced by the coupling of pressure-driven and electroosmotic flow caused by the patterned electrodes can decrease axial dispersion . According to recent experimental work, the AC electroosmotic flow can minimize Taylor–Aris dispersion even further by generating vortices in open-tubular microfluidic channels while subjected to an axial pressure gradient .…”

Section: Introductionmentioning

confidence: 99%

AC Electrothermal Effect Promotes Enhanced Solute Mixing in a Wavy Microchannel

Mehta,

Mondal

2023

Langmuir

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For liquids used in biological applications, a smaller diffusion coefficient results in a longer mixing time. We discuss, in this endeavor, the promising potential of the AC electrothermal (ACET) effect toward modulating enhanced mixing of electrolytic liquids with higher convective strength in a novel wavy micromixer. To this end, we develop a modeling framework and numerically solve the pertinent transport equations in a three-dimensional (3D) configuration numerically. By benchmarking the developed modeling framework with the experimental results available in this paradigm, we aptly demonstrate the maximum temperature rise, flow topology, species concentration field, and mixing efficiency in the proposed configuration for a set of parameters pertinent to this analysis. We find that the maximum temperature increase in the wavy micromixer, owing to the electrothermal effect, is less than 10 K even for the higher strength of the applied voltage, implying nondegradation of biological substances within the liquid sample. We report that the formation of significant lateral flow closer to the electrodes leads to a highly three-dimensional ACET flow field, which has a significant impact on the mixing efficiency for the range of diffusive Peclet numbers considered. We also report that the wave amplitude of the mixer, when intervening with the diffusive Peclet number, strongly impacts the mixing efficiency. As witnessed in this endeavor, for the smaller diffusive Peclet number, the mixing efficiency increases with amplitude, while the effect becomes the opposite for the higher Peclet number. The results of this study seem to provide an adequate basis for the design of a novel micromixer intended for enhanced solute mixing in realistic microfluidic applications.

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Taming Taylor-Aris dispersion through chaotic advection

Cited by 11 publications

References 43 publications

C-Term Reduction in 3 μm Open-Tubular High-Aspect-Ratio Channels in AC-EOF Vortex Chromatography Operation

C-Term Reduction in 3 μm Open-Tubular High-Aspect-Ratio Channels in AC-EOF Vortex Chromatography Operation

Microfluidic Validation of the Diffusional Bridging Effect Suppressing Dispersion in Multicapillary Flow Systems

AC Electrothermal Effect Promotes Enhanced Solute Mixing in a Wavy Microchannel

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