Transport Dynamics in Open Microfluidic Grooves

Baret, Jean‐Christophe; Decré, M.; Herminghaus, Stephan; Seemann, Ralf

doi:10.1021/la063584c

Cited by 61 publications

(61 citation statements)

References 29 publications

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“…W, the aspect ratio function  o ()1. It should be noted that alternative, but equivalent Fourier series solutions for the flow in an open rectangular exist, such as that in Baret et al (2007) and Yang et al (2011).…”

Section: Viscous Terms and Interpolation Formulaementioning

confidence: 99%

“…Strage et al, 2003), rectangular (e.g. Ichikawa et al, 2004;Jong et al, 2007;Zhu and Petkovic-Duran, 2010) and grooved/triangular (Yost and Holm, 1995;Romero and Yost, 2006;Baret et al, 2007). Moreover, the same approach has been taken for channels defined by hydrophilic paths on a hydrophobic substrate (Darhuber et al, 2001) and by the space between two parallel plates (Rosendahl et al, 2004) under the assumption of flow with low Reynolds number and liquid imbibing in a tube/slablike manner.…”

Section: Introductionmentioning

confidence: 99%

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Wetting considerations in capillary rise and imbibition in closed square tubes and open rectangular cross-section channels

Ouali

McHale

Javed

et al. 2013

Microfluid Nanofluid

149

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The spontaneous capillary-driven filling of microchannels is important for a wide range of applications. These channels are often rectangular in cross-section, can be closed or open, and horizontal or vertically orientated. In this work, we develop the theory for capillary imbibition and rise in channels of rectangular cross-section, taking into account rigidified and non-rigidified boundary conditions for the liquid-air interfaces and the effects of surface topography assuming Wenzel or Cassie-Baxter states. We provide simple interpolation formulae for the viscous friction associated with flow through rectangular cross-section channels as a function of aspect ratio. We derive a dimensionless cross-over time, T c , below which the exact numerical solution can be approximated by the Bousanquet solution and above which by the visco-gravitational solution. For capillary rise heights significantly below the equilibrium height, this cross-over time is T c  (3X e /2) 2/3 and has an associated dimensionless crossover rise height X c  (3X e /2) 1/3 , where X e =1/G is the dimensionless equilibrium rise height and G is a dimensionless form of the acceleration due to gravity. We also show from wetting considerations that for rectangular channels, fingers of a wetting liquid can be expected to imbibe in advance of the main meniscus along the corners of the channel walls. We test the theory via capillary rise experiments using polydimethylsiloxane oils of viscosity 96.0, 48.0, 19.2 and 4.8 mPa s within a range of closed square tubes and open rectangular cross-section channels with SU-8 walls. We show that the capillary rise heights can be fitted using the exact numerical solution and that these are similar to fits using the analytical visco-gravitational solution. The viscous friction contribution was found to be slightly higher than predicted by theory assuming a non-rigidified liquid-air boundary, but far below that for a rigidified boundary, which was recently reported for imbibition into horizontally mounted open microchannels. In these experiments we also observed fingers of liquid spreading along the internal edges of the channels in advance of the main body of liquid consistent with wetting expectations. We briefly discuss the implications of these observations for the design of microfluidic systems.

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Section: Viscous Terms and Interpolation Formulaementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Wetting considerations in capillary rise and imbibition in closed square tubes and open rectangular cross-section channels

Ouali

McHale

Javed

et al. 2013

Microfluid Nanofluid

149

View full text Add to dashboard Cite

show abstract

“…This electrowetting-on-dielectric effect with voltage control of the equilibrium contact angle has found application in droplet microfluidics 8,9 , liquid-lenses 10,11 and electronic paper 12 . It has also been used to induce morphological changes from a spherical cap droplet shape to a stripe droplet shape and to study dynamics of filaments wetting along open, rectangular microfluidic grooves 13,14 , and to increase maximum coating speeds by delaying air entrainment 15 .…”

mentioning

confidence: 99%

Voltage-induced spreading and superspreading of liquids

2013

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The ability to quickly spread a liquid across a surface and form a film is fundamental for a diverse range of technological processes, including printing, painting and spraying. Here we show that liquid dielectrophoresis or electrowetting can produce wetting on normally nonwetting surfaces, without needing modification of the surface topography or chemistry. Additionally, superspreading can be achieved without needing surfactants in the liquid. Here we use a modified Hoffman-de Gennes law to predict three distinct spreading regimes: exponential approach to an equilibrium shape, spreading to complete wetting obeying a Tanner's law-type relationship and superspreading towards a complete wetting film. We demonstrate quantitative experimental agreement with these predictions using dielectrophoresis-induced spreading of stripes of 1,2 propylene glycol. Our findings show how the rate of spreading of a partial wetting system can be controlled using uniform and non-uniform electric fields and how to induce more rapid superspreading using voltage control.

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“…According to the Wenzel model, the roughness of solid surfaces enhances their hydrophilic/ lipophilic properties 17 . On model B, which has deep microwrinkles, the oil droplet forms a spherical lens with a low contact angle due to the large surface area 18 . Another interesting phenomenon was the appearance of a wicking front.…”

Section: Shape and Physical Properties Of Arti Cial Skin Modelmentioning

confidence: 99%