Transverse transport of solutes between co-flowing pressure-driven streams for microfluidic studies of diffusion/reaction processes
Abstract
We consider a situation commonly encountered in microfluidics: two streams of miscible liquids are brought at a junction to flow side by side within a microchannel, allowing solutes to diffuse from one stream to the other and possibly react. We focus on two model problems: (i) the transverse transport of a single solute from a stream into the adjacent one, (ii) the transport of the product of a diffusion-controlled chemical reaction between solutes originating from the two streams. Our description is made general through a non-dimensionalized formulation that incorporates both the parabolic Poiseuille velocity profile along the channel and thermal diffusion in the transverse direction. Numerical analysis over a wide range of the streamwise coordinate reveal different regimes. Close to the top and the bottom walls of the microchannel, the extent of the diffusive zone follows three distinct power law regimes as is increased, characterized respectively by the exponents 1/2, 1/3 and 1/2. Simple analytical arguments are proposed to account for these results.
Cite
@article{arxiv.cond-mat/0702023,
title = {Transverse transport of solutes between co-flowing pressure-driven streams for microfluidic studies of diffusion/reaction processes},
author = {Jean-Baptiste Salmon and Armand Ajdari},
journal= {arXiv preprint arXiv:cond-mat/0702023},
year = {2007}
}