Maximizing diffusiophoretic extraction from confined geometries using time-varying solute strategies

This work explores the impact of solute concentration at the boundary of a domain on the gradient-induced motion of colloidal particles. This phenomenon, known as diffusiophoresis, has the potential to improve efficiency of particle motion through confined geometry by orders of magnitude over that of simple Brownian motion. For example, previous research has found that near-discontinuous solute concentration at the boundary of a pore can lead to significantly enhanced efficiency of motion. We expand upon that finding, using both simulations and experiments, to understand more complex boundary conditions. In particular, we test singular and pulsing near-discontinuities in the solute gradient, and compare the resulting efficiencies of their induced motion. We conclude that these modified conditions can further strengthen the diffusiophoretic motion, and therefore the efficiency of injection and withdrawal processes. This could lead to great enhancements of such processes as oil recovery or targeted drug delivery.