Stick-slip motion and controlled filling speed by the geometric design of soft micro-channels

Johanna Andersson; Anette Larsson; Anna Ström

doi:10.1016/j.jcis.2018.03.070

Stick-slip motion and controlled filling speed by the geometric design of soft micro-channels

J Colloid Interface Sci. 2018 Aug 15:524:139-147. doi: 10.1016/j.jcis.2018.03.070. Epub 2018 Mar 22.

Authors

Johanna Andersson¹, Anette Larsson¹, Anna Ström²

Affiliations

¹ Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, Sweden; SuMo Biomaterials, VINN Excellence Centre, Chalmers University of Technology, Gothenburg, Sweden.
² Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg, Sweden; SuMo Biomaterials, VINN Excellence Centre, Chalmers University of Technology, Gothenburg, Sweden. Electronic address: anna.strom@chalmers.se.

PMID: 29649622
DOI: 10.1016/j.jcis.2018.03.070

Abstract

Hypothesis: Liquid can move by capillary action through interconnected porous materials, as in fabric or paper towels. Today mass transport is controlled by chemical modification. It is, however, possible to direct mass transport by geometrical modifications. It is here proposed that it is possible to tailor capillary flow speed in a model system of micro-channels by the angle, size and position of attached side channels.

Experiments: A flexible, rapid, and cost-effective method is used to produce micro-channels in gels. It involves 3D-printed moulds in which gels are cast. Open channels of micrometre size with several side channels on either one or two sides are produced with tilting angles of 10-170°. On a horizontal plane the meniscus of water driven by surface tension is tracked in the main channel.

Findings: The presence of side channels on one side slowed down the speed of the meniscus in the main channel least. Channels having side channels on both sides with tilting angles of up to 30° indicated tremendously slower flow, and the liquid exhibited a stick-slip motion. Broader side channels decreased the speed more than thinner ones, as suggested by the hypothesis. Inertial forces are suggested to be important in branched channel systems studied here.

Keywords: Capillary action; Foam structures; Lucas–Washburn equation; Pinning meniscus.