Effect of surfactant on emulsification in microchannels

Kovalchuk, N. M.; Roumpea, Evangelia; Nowak, Emilia; Chinaud, Maxime; Angeli, Panagiota; Simmons, Mark

doi:10.1016/j.ces.2017.10.026

Cited by 71 publications

(53 citation statements)

References 52 publications

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“…Therefore, a comprehensive study of other surfactants with different CMC values and in a range of concentrations is required to make more general conclusions on the effect of surfactant on the film thickness. It can be suggested from the discussion above that if an increase in the film thickness is due to depletion of surfactant from the leading edge of displacing liquid then using slower equilibrating surfactants, such as Triton X‐100 or hexadecytrimethylammonium bromide (CTAB) should result in further decrease of film thickness, whereas increase in concentration of SDS or other quickly equilibrated surfactant (e.g., dodecyltrimethylammonum bromide)will eventually increase the film thickness back to the value expected for the capillary number based on surface tension of surfactant solution.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Residual film thickness following immiscible fluid displacement in noncircular microchannels at large capillary number

Kovalchuk

Simmons

2018

AIChE Journal

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An experimental study of the displacement of one immiscible fluid by another was performed in microchannels with circular, square and near‐semicircular cross‐sections, with hydraulic diameters from 100 to 200 μm. Experiments were performed over a range of capillary number, Ca, from 0.02 < Ca < 80, with viscosity ratios between the two fluids ranging from 20 to 100. The liquid film left on the channel wall following the advance of the displacing fluid was obtained from visual measurements and a method for the estimation of mean film thickness was shown to be in good agreement with existing correlations. The addition of a surfactant (Sodium Dodecyl Sulfate, SDS) dissolved in the displacing fluid led to a reduction in the thickness of the residual film. © 2018 The Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 64: 3456–3466, 2018

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Section: Resultsmentioning

confidence: 99%

“…The dynamic surface tension values are used to estimate the dynamic interfacial tension between the displaced fluid and the displacing fluid with SDS added, following the strategy below, which was proposed recently

\frac{γ_{0} - γ_{s}}{σ_{0} - σ_{s}} = \frac{γ_{0} - γ_{s t}}{σ_{0} - σ_{s t}}

…”

Section: Methodsmentioning

confidence: 99%

Residual film thickness following immiscible fluid displacement in noncircular microchannels at large capillary number

Kovalchuk

Simmons

2018

AIChE Journal

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“…According to the Web of Science, the number of articles published on flow-focusing microfluidics over the last 2 years was four and ten times larger than for T-junction and co-flow designs, respectively. Flow focusing can be achieved in various ways: by interaction of the flows of dispersed and continuous phases in a cross-junction (hydrodynamic focusing) (Cubaud and Mason 2008;Carrier et al 2015;Chen et al 2015), by passing coflowing dispersed and continuous phases through an orifice (geometrical focusing) (Anna et al 2003;Garstecki et al 2005;Lee et al 2009), by combination of hydrodynamic and geometrical focusing (Ward et al 2010;Kovalchuk et al 2018b) or by optical focusing (de Saint Vincent and Delville 2016).…”

Section: Introductionmentioning

confidence: 99%

“…Flow-focusing devices produce drops in four different regimes which are denoted as squeezing, dripping, jetting and tip streaming (Anna and Mayer 2006;Cubaud and Mason 2008;Lee et al 2009;Kovalchuk et al 2018b). The squeezing regime usually results in the formation of plugs with a length larger than the channel width whilst smaller drops are formed in the dripping regime.…”

Section: Introductionmentioning

confidence: 99%

Drop formation in microfluidic cross-junction: jetting to dripping to jetting transition

Kovalchuk

Sagisaka

Steponavicius

et al. 2019

Microfluid Nanofluid

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The regimes of drop generation were studied in a Dolomite microfluidic device which combined both hydrodynamic and geometrical flow focusing over a broad range of flow rates. A series of aqueous dispersed phases were used with a viscosity ratio between continuous and dispersed phases of close to unity. Surfactants were added to alter the interfacial tension. It was shown that the transition from dripping to jetting is well described by the capillary numbers of both the dispersed and continuous phases. Only the jetting regime was observed if the capillary number of the dispersed phase was above a critical value, whereas at smaller values of this parameter a jetting → dripping → jetting transition was observed by increasing the capillary number of the continuous phase. The analysis performed has shown that the conditions for a dripping to jetting transition at moderate and large values of the capillary number of the continuous phase can be predicted theoretically by comparison of the characteristic time scales for drop pinch-off and jet growth, whereas the transition at small values cannot. It is suggested that this transition is geometry mediated and is a result of the interplay of jet confinement in the focusing part and a decrease of confinement following entry into the main channel. The flow fields inside the jet of the dispersed phase were qualitatively different for small and large values of the capillary number of the continuous phase revealing the relative contribution of the dispersed phase flow in jet formation. The volume of the drops formed in the jetting regime increased as a power law function of the flow rate ratio of the dispersed to continuous phase, independent of the interfacial tension.

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“…This bubble formation problem was not observed when D-PBS(-) was used. This is related to the innate characteristic of a surfactant-containing solution that forms a thin plug deposit in a microchannel as a trailing film under low pressure [44]. As for the percentage of microwells containing single trapped bead, a decreasing trend with increasing sheet thickness (30 µm: 31%, 60 µm: 29% and 90 µm: 22%) was observed as shown in Figure 4b.…”

Section: Neutrophil Isolation Capabilitymentioning

confidence: 77%

Single Cell Analysis of Neutrophils NETs by Microscopic LSPR Imaging System

et al. 2019

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A simple microengraving cell monitoring method for neutrophil extracellular traps (NETs) released from single neutrophils has been realized using a polydimethylsiloxane (PDMS) microwell array (MWA) sheet on a plasmon chip platform. An imbalance between NETs formation and the succeeding degradation (NETosis) are considered associated with autoimmune disease and its pathogenesis. Thus, an alternative platform that can conduct monitoring of this activity on single cell level at minimum cost but with great sensitivity is greatly desired. The developed MWA plasmon chips allow single cell isolation of neutrophils from 150 µL suspension (6.0 × 105 cells/mL) with an efficiency of 36.3%; 105 microwells with single cell condition. To demonstrate the utility of the chip, trapped cells were incubated between 2 to 4 h after introducing with 100 nM phorbol 12-myristate 13-acetate (PMA) before measurement. Under observation using a hyperspectral imaging system that allows high-throughput screening, the neutrophils stimulated by PMA solution show a significant release of fibrils and NETs after 4 h, with observed maximum areas between 314–758 µm2. An average absorption peak wavelength shows a redshift of Δλ = 1.5 nm as neutrophils release NETs.

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Effect of surfactant on emulsification in microchannels

Cited by 71 publications

References 52 publications

Residual film thickness following immiscible fluid displacement in noncircular microchannels at large capillary number

Residual film thickness following immiscible fluid displacement in noncircular microchannels at large capillary number

Drop formation in microfluidic cross-junction: jetting to dripping to jetting transition

Single Cell Analysis of Neutrophils NETs by Microscopic LSPR Imaging System

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