Directional liquid wicking in regular arrays of triangular posts

Liu, Bang-Yan, Chen, Li-Jen, Seemann, Ralf and Brinkmann, Martin (2019) Directional liquid wicking in regular arrays of triangular posts. Langmuir, 35 (50). pp. 16476-16486. ISSN 0743-7463

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Official URL: https://doi.org/10.1021/acs.langmuir.9b03032

Abstract

Wicking of wetting liquids into micropatterns of posts with homogeneous triangular cross section is studied in experiments and by numerical energy minimizations. To test for directional wicking, we fabricated regular arrays of posts with various combinations of line fractions and aspect ratios using standard photolithography processes. In agreement with numerical energy minimizations of the liquid film morphology, we find spontaneous wicking in the experiments only for line fractions and aspect ratios where the homogeneous liquid film represents the state of lowest interfacial free energy and where no local energy minimum could be detected in our numerical energy minimizations. The numerical results further demonstrate that the stability of a certain morphology of the terminal meniscus controls the direction of wicking relative to the orientation of the triangular posts. The observed selectivity of spontaneous wicking with respect to the meniscus orientation can be exploited to build a microfluidic rectifier for partially wetting liquids.

Item Type: Article
Uncontrolled Keywords: wetting of micro-pattern, wicking, directional wetting
Subjects: F300 Physics
Department: Faculties > Engineering and Environment > Mathematics, Physics and Electrical Engineering
Depositing User: Ay Okpokam
Date Deposited: 22 Nov 2019 10:43
Last Modified: 08 Jan 2020 17:00
URI: http://nrl.northumbria.ac.uk/id/eprint/41587

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