Surface tension driven flow for open microchannels with different turning angles

Chen, Yufeng; Tseng, Fan‐Gang; ChangChien, Shang-Yu; Chen, Ming-Hung; Yu, Ru-Ji; Chieng, Ching-Chang

doi:10.1007/s10404-007-0237-5

Cited by 27 publications

(21 citation statements)

References 27 publications

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“…Figure 5 shows the time evolution of the meniscus centerline velocity for PDMS microchannel with isopropyl alcohol. The velocity of the advancing liquid front at x-position is obtained by the derivative of the liquid front position (Chen et al 2008) with time at time = t. The centerline velocity decreases with time. This being a nonsteady process, the interface is in nonequilibrium state relaxing to a configuration of minimum free energy and hence, the velocity is observed to be a decreasing function of time (Barraza et al 2002).…”

Section: Flow Visualizationmentioning

confidence: 99%

Experimental and numerical investigation of capillary flow in SU8 and PDMS microchannels with integrated pillars

Saha

Mitra

Tweedie

et al. 2009

Microfluid Nanofluid

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Microfluidic channels with integrated pillars are fabricated on SU8 and PDMS substrates to understand the capillary flow. Microscope in conjunction with highspeed camera is used to capture the meniscus front movement through these channels for ethanol and isopropyl alcohol, respectively. In parallel, numerical simulations are conducted, using volume of fluid method, to predict the capillary flow through the microchannels with different pillar diameter to height ratio, ranging from 2.19 to 8.75 and pillar diameter to pitch ratio, ranging from 1.44 to 2.6. The pillar size (diameter, pitch and height) and the physical properties of the fluid (surface tension and viscosity) are found to have significant influence on the capillary phenomena in the microchannel. The meniscus displacement is non-uniform due to the presence of pillars and the nonuniformity in meniscus displacement is observed to increase with decrease in pitch to diameter ratio. The surface area to volume ratio is observed to play major roles in the velocity of the capillary meniscus of the devices. The filling speed is observed to change more dramatically under different pillar heights upto 120 lm and the change is slow with further increase in the pillar height. The details pertaining to the fluid distribution (meniscus front shapes) are obtained from the numerical results as well as from experiments. Numerical predictions for meniscus front shapes agree well with the experimental observations for both SU8 and PDMS microchannels. It is observed that the filling time obtained experimentally matches very well with the simulated filling time. The presence of pillars creates uniform meniscus front in the microchannel for both ethanol and isopropyl alcohol. Generalized plots in terms of dimensionless variables are also presented to predict the performance parameters for the design of these microfluidic devices. The flow is observed to have a very low Capillary number, which signifies the relative importance of surface tension to viscous effects in the present study.

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Section: Flow Visualizationmentioning

confidence: 99%

Experimental and numerical investigation of capillary flow in SU8 and PDMS microchannels with integrated pillars

Saha

Mitra

Tweedie

et al. 2009

Microfluid Nanofluid

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“…The mathematical model of the present work includes fluid modeling, solid structure modeling, and fluid-structure coupling, which will be described in following sections. Numerical simulations are performed using computer software CFD-ACE+ 2006 and successful simulations have been obtained using CFD-ACE+ for two-phase flows in microscale (for example, Weber and Shandas 2007;Chen et al 2007). …”

Section: Mathematical Modelmentioning

confidence: 99%

Numerical studies on micropart self-alignment using surface tension forces

Lin

Tseng

Kan

et al. 2008

Microfluid Nanofluid

Self Cite

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The Fluidic Self-Alignment Approach provides an alternative means for fast, economic, and precise handling of thousands of micro-scale parts. The present study aims to examine the important parameters which govern the mechanisms of the fluidic self-assembly process by numerical simulations. A simplified 2D model system consists of a solid plate, a micro-scale liquid slug and a micropart. The computational model is based on first principle conservation equations and is constructed by the coupling of two-phase modeling, solid structure modeling, and fluid-structure coupling. A matching experimental system is set up for the micropart of aspect ratio from 3:1 to 10:1 to validate the 2D computational simulations. Simulations reveal that a high degree of hydrophilicity between the lubricant and the solid surfaces is required for the self-assembly of microparts. A lower lubricant height, a higher surface tension coefficient and a higher viscosity enforce the re-alignment/restoration process also. Characterization of the flow field inside lubricant slug also indicates that the asymmetry of the vortices/stress distribution at both ends of the lubricant meniscus is resulted as the micropart in a back-and-forth restoration process.

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“…In the surface force model, the surface tension force was considered as a surface force (pressure) according to the Laplace equation [1,3,4,10,11], and then was introduced in the solution as a pressure boundary on the meltfront. While in the volume force model, the surface tension force was considered as a volume force [9,[12][13][14]. The basic concept of this model was the continuum surface force (CSF) model proposed by Brackbill in Ref.…”

Section: Introductionmentioning

confidence: 99%