Journal
LANGMUIR
Volume 34, Issue 4, Pages 1394-1399Publisher
AMER CHEMICAL SOC
DOI: 10.1021/acs.langmuir.7b03962
Keywords
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Funding
- LAAS-CNRS micro and nano technologies platform
- ANR PolyTransFlow [13-BS09-0015]
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We investigate the pressure-driven transport of particles 200 or 300 nm in diameter in shallow microfluidic channels similar to 1 mu m in height with a bottom wall characterized by a high roughness amplitude of similar to 100 nm. This study starts with the description of an assay to generate cracks in hydrophilic thin polymer films together with a structural characterization of these corrugations. Microfluidic chips of variable height are then assembled on top of these rough surfaces, and the transport of particles is assessed by measuring the velocity distribution function for a set of pressure drops. We specifically detect anomalous transport properties for rough surfaces. The maximum particle velocity at the centerline of the channel is comparable to that obtained with smooth surfaces, but the average particle velocity increases nonlinearly with the flow rate. We suggest that the change in the boundary condition at the rough wall is not sufficient to account for our data and that the occurrence of contacts between the particle and the surface transports the particle away from the wall and speeds up its motion. We finally draw perspectives for the separation by field-flow fractionation.
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