Diffusiophoresis and diffusioosmosis in a junction device with a long microchannel: colloid dynamics and particle characterisation
Author(s)
Puijk, Christina
Chakra, Adnan
Vladisavljević, Goran T
Bolognesi, Guido
Type
Journal Article
Abstract
The dynamics of carboxyl-modified polystyrene colloidal particles of varying size and zeta potential were investigated in a microfluidic junction device where merging electrolyte streams generated a steady-state salt concentration gradient. The device featured a long microchannel downstream of the junction, enabling the particle dynamics to be analysed over a time scale comparable to the relaxation time of the salt gradient. In the bulk of the channel, particles migrate outwards through a diffusive-like process arising from the additive contributions of particle diffusiophoresis and wall diffusioosmosis. An analytical expression is derived for the effective diffusion coefficient, and a microfluidic approach is proposed to estimate particle diffusiophoretic mobility. Particles accumulated at the walls also displace sideways but the direction of their motion depends on the counter-acting effects of particle diffusiophoresis and wall diffusioosmosis. This motion is sub-diffusive at short distances from the junction, but either ceases or reverses further downstream. The intensity of the accumulation peaks exhibits a non-monotonic dependence on the distance from the junction and, after calibration, can serve for the microfluidic measurement of particle size or zeta potential, when one property is known a priori. The influence of electric double layer polarisation on diffusiophoretic mobility is also examined.
Date Issued
2026-01-01
Date Acceptance
2026-07-02
Citation
Flow, 2026, 6
ISSN
2633-4259
Publisher
Cambridge University Press
Journal / Book Title
Flow
Volume
6
Copyright Statement
© The Author(s), 2026. Published by Cambridge University Press This is an Open Access article, distributed under the terms of the Creative Commons Attribution licence (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted re-use, distribution and reproduction, provided the original article is properly cited.
License URL
Publication Status
Published
Article Number
E26
Date Publish Online
2026-09-01