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Microfluidic free interface diffusion: Measurement of diffusion coefficients and evidence of interfacial-driven transport phenomena.
- Source :
-
Physics of Fluids . May2022, Vol. 34 Issue 5, p1-11. 11p. - Publication Year :
- 2022
-
Abstract
- We have developed a microfluidic tool to measure the diffusion coefficient D of solutes in an aqueous solution by following the temporal relaxation of an initially steep concentration gradient in a microchannel. Our chip exploits multilayer soft lithography and the opening of a pneumatic microvalve to trigger the interdiffusion of pure water and the solution initially separated in the channel by the valve, the so-called free interface diffusion technique. Another microvalve at a distance from the diffusion zone closes the channel and thus suppresses convection. Using this chip, we have measured diffusion coefficients of solutes in water with a broad size range, from small molecules to polymers and colloids, with values in the range D ∈ [ 10 − 13 – 10 − 9 ] m2/s. The same experiments but with added colloidal tracers also revealed diffusio-phoresis and diffusio-osmosis phenomena due to the presence of the solute concentration gradient. We nevertheless show that these interfacial-driven transport phenomena do not affect the measurements of the solute diffusion coefficients in the explored concentration range. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 10706631
- Volume :
- 34
- Issue :
- 5
- Database :
- Academic Search Index
- Journal :
- Physics of Fluids
- Publication Type :
- Academic Journal
- Accession number :
- 157217228
- Full Text :
- https://doi.org/10.1063/5.0092280