Williams, I;
Lee, S;
Apriceno, A;
Sear, RP;
Battaglia, G;
(2020)
Diffusioosmotic and convective flows induced by a nonelectrolyte concentration gradient.
Proceedings of the National Academy of Sciences (PNAS)
10.1073/pnas.2009072117.
Preview |
Text
2009072117.full.pdf - Published Version Download (1MB) | Preview |
Abstract
Glucose is an important energy source in our bodies, and its consumption results in gradients over length scales ranging from the subcellular to entire organs. Concentration gradients can drive material transport through both diffusioosmosis and convection. Convection arises because concentration gradients are mass density gradients. Diffusioosmosis is fluid flow induced by the interaction between a solute and a solid surface. A concentration gradient parallel to a surface creates an osmotic pressure gradient near the surface, resulting in flow. Diffusioosmosis is well understood for electrolyte solutes, but is more poorly characterized for nonelectrolytes such as glucose. We measure fluid flow in glucose gradients formed in a millimeter-long thin channel and find that increasing the gradient causes a crossover from diffusioosmosis-dominated to convection-dominated flow. We cannot explain this with established theories of these phenomena which predict that both scale linearly. In our system, the convection speed is linear in the gradient, but the diffusioosmotic speed has a much weaker concentration dependence and is large even for dilute solutions. We develop existing models and show that a strong surface–solute interaction, a heterogeneous surface, and accounting for a concentration-dependent solution viscosity can explain our data. This demonstrates how sensitive nonelectrolyte diffusioosmosis is to surface and solution properties and to surface–solute interactions. A comprehensive understanding of this sensitivity is required to understand transport in biological systems on length scales from micrometers to millimeters where surfaces are invariably complex and heterogeneous.
| Type: | Article |
|---|---|
| Title: | Diffusioosmotic and convective flows induced by a nonelectrolyte concentration gradient |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1073/pnas.2009072117 |
| Publisher version: | https://doi.org/10.1073/pnas.2009072117 |
| Language: | English |
| Additional information: | This open access article is distributed under Creative Commons Attribution-NonCommercial-NoDerivatives License 4.0 (CC BY-NC-ND). |
| Keywords: | Diffusioosmosis, convection, microfluidics |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > Dept of Chemistry |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10111409 |
Archive Staff Only
 |
View Item |
