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Updated: Jun 19, 2026

The Diffusion of Passive Tracers in Laminar Shear Flow
Published on: May 1, 2018
Imbibition in porous membranes of complex shape: quasi-stationary flow in thin rectangular segments
Sergio Mendez1, Erin M Fenton, Gil R Gallegos
1Center for Biomedical Engineering, and Department of Chemical and Nuclear Engineering, University of New Mexico, Albuquerque, New Mexico 87131, USA.
Abstract:
The sustained liquid flow of a typical lateral flow assay can be mimicked by two-dimensional shaped, thin porous membranes, specifically rectangular membranes appended to circular sectors. In designing these fan-shaped devices, we have been aided by analytical equations and finite-element simulations. We show both mathematically and experimentally how a continuous increase in unwetted pore volume causes a deviation from traditional imbibition, and leads to quasi-stationary flow in the rectangular element. These results are both theoretically and practically important because they indicate how medical diagnostic test strips may be fabricated without incorporating an absorbent pad.
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