Wicking through a confined micropillar array
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This study considers the spreading of a Newtonian and perfectly wetting liquid in a square array of cylindric micropillars confined between two plates. We show experimentally that the dynamics of the contact line follows a Washburn-like law which depends on the characteristics of the micropillar array (height, diameter and pitch). The presence of pillars can either enhance or slow down the motion of the contact line. A theoretical model based on capillary and viscous forces has been developed in order to rationalize our observations. Finally, the impact of pillars on the volumic flow rate of liquid which is pumped in the microchannel is inspected.
KeywordsMicrochannel wicking Micropillar array Liquid impregnation
This research has been funded by the Inter-university Attraction Poles Programme (IAP 7/38 MicroMAST) initiated by the Belgian Science Policy Office. SD thanks the FNRS for financial support. We acknowledge Mathilde Reyssat, Tristan Gilet and Pierre Colinet for fruitful discussions and valuable comments. We are grateful to Stéphanie Van Loo for precious advices concerning the realization of the PDMS microchannels.