The marching velocity of the capillary meniscus in a microchannel

Yang, Lung‐Jieh; Yao, Tze-Jung; Tai, Yu‐Chong

doi:10.1088/0960-1317/14/2/008

Cited by 131 publications

(109 citation statements)

References 8 publications

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“…Other filling kinetics studies of channels with rectangular cross-section were performed with much larger channels. Yang et al reported the marching velocity of capillary menisci in 500-nm-deep silicon nitride channels [18]. Hibara et al reported filling kinetics in 300-nm-deep channels fabricated in fused silica [16].…”

Section: Washburn Kinetics In Channels With Different Depthmentioning

confidence: 99%

Filling kinetics of liquids in nanochannels as narrow as 27 nm by capillary force

Han

Mondin

Hegelbach

et al. 2006

Journal of Colloid and Interface Science

107

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We report the filling kinetics of different liquids in nanofabricated capillaries with rectangular cross-section by capillary force. Three sets of channels with different geometry were employed for the experiments. The smallest dimension of the channel cross-section was respectively 27, 50, and 73 nm. Ethanol, isopropanol, water and binary mixtures of ethanol and water spontaneously filled nanochannels with inner walls exposing silanol groups. For all the liquids the position of the moving liquid meniscus was observed to be proportional to the square root of time, which is in accordance with the classical Washburn kinetics. The velocity of the meniscus decreased both with the dimension of the channel and the ratio between the surface tension and the viscosity. In the case of water, air-bubbles were spontaneously trapped as channels were filled. For a binary mixture of 40% ethanol and water, no trapping of air was observed anymore. The filling rate was higher than expected, which also corresponds to the dynamic contact angle for the mixture being lower than that of pure ethanol. Nanochannels and porous materials share many physicochemical properties, e.g., the comparable pores size and extremely high surface to volume ratio. These similarities suggest that our nanochannels could be used as an idealized model to study mass transport mechanisms in systems where surface phenomena dominate.

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Section: Washburn Kinetics In Channels With Different Depthmentioning

confidence: 99%

Filling kinetics of liquids in nanochannels as narrow as 27 nm by capillary force

Han

Mondin

Hegelbach

et al. 2006

Journal of Colloid and Interface Science

107

View full text Add to dashboard Cite

show abstract

“…Capillary flows at micro-and nano-scale have been of great interest in recent years for their importance in microfluidic devices. Yang et al [11] showed that at 10 lm scale the measured height-time curve exhibited the Lucas-Washburn behavior. Tas et al [12] demonstrated experimentally that at 100 nm scale the capillary flows also followed the conclusion of Lucas-Washburn if the electro-viscous effect was expelled.…”

Section: Introductionmentioning

confidence: 99%

Capillary Filling Flows inside Patterned‐Surface Microchannels

Huang

Liu

2006

Chem Eng & Technol

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Capillary flows inside microchannels with patterned-surfaces are investigated theoretically and numerically. The surface energy method is used to derive an equivalent contact angle (ECA) model for small capillary number flows. The SIMPLE algorithm using a volume of fluid (VOF) method is adopted to investigate the flows in those microchannels. The flow characteristics such as the liquid front shapes and the evolution of the liquid lengths are obtained. The numerical results reveal that capillary flows in a patterned-surface microchannel still follow the traditional capillary theories. The ECA model is confirmed by the numerical results. It indicates that the capillary flows inside the patterned-surface microchannels can be estimated by means of the homogeneous-surface microchannels with the equivalent contact angle. The ECA model provides a good criterion for the total wettability of a patterned-surface microchannel, as well.

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“…In contrast, a study of a model for decane molecules in a carbon nanotube [14,15] yielded a simple linear behavior H(t) ∝ t over a wide range of times, leading to the conclusion that filling of nanotubes by fluids does not obey the Lucas-Washburn equation. Experiments so far are inconclusive on this issue, since the existing work [16,17] deals only with pores that are at least 1 µm wide. Moreover, in narrow nanotubes an eventual slip at the hydrodynamic boundaries might afTypeset by REVT E X fect the balance of forces by reducing the viscous drag at the tube wall.…”

mentioning

confidence: 99%

Capillary Rise in Nanopores: Molecular Dynamics Evidence for the Lucas-Washburn Equation

2007

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When a capillary is inserted into a liquid, the liquid will rapidly flow into it. This phenomenon, well studied and understood on the macroscale, is investigated by Molecular Dynamics simulations for coarse-grained models of nanotubes. Both a simple Lennard-Jones fluid and a model for a polymer melt are considered. In both cases after a transient period (of a few nanoseconds) the meniscus rises according to a √ time-law. For the polymer melt, however, we find that the capillary flow exhibits a slip length δ, comparable in size with the nanotube radius R. We show that a consistent description of the imbibition process in nanotubes is only possible upon modification of the Lucas-Washburn law which takes explicitly into account the slip length δ. We also demonstrate that the velocity field of the rising fluid close to the interface is not a simple diffusive spreading.

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The marching velocity of the capillary meniscus in a microchannel

Cited by 131 publications

References 8 publications

Filling kinetics of liquids in nanochannels as narrow as 27 nm by capillary force

Filling kinetics of liquids in nanochannels as narrow as 27 nm by capillary force

Capillary Filling Flows inside Patterned‐Surface Microchannels

Capillary Rise in Nanopores: Molecular Dynamics Evidence for the Lucas-Washburn Equation

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