Wicking through a confined micropillar array

TL;DR

This paper investigates how a wetting liquid spreads through a confined micropillar array, revealing that pillar characteristics influence the contact line dynamics and flow rate, supported by experiments and a theoretical model.

Contribution

It introduces a theoretical model explaining contact line dynamics in micropillar arrays and experimentally demonstrates how pillar properties affect spreading behavior.

Findings

Contact line follows a Washburn-like law influenced by pillar geometry.

Pillars can either accelerate or decelerate liquid spreading.

Pillars impact the volumic flow rate in microchannels.

Abstract

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 enhanced 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.