Enhancing Controlled Colloidal Migration Through Engineering Soluto-Inertial Synergy

The interactions and forces that are relevant at the colloidal scale are well understood. However, our ability to control colloidal behavior is limited by the fact that equilibrium interactions are typically restricted to the micron scale, and often much less. We demonstrate various strategies to circumvent this limitation, using millimeter scale, non-equilibrium suspension interactions enabled by soluto-inertial (SI) "beacons". These beacons establish and maintain long-lived, non-equilibrium solute fluxes in solution that drive colloidal particles to migrate via diffusiophoresis (DP). We explore the consequences of the SI phenomenon and demonstrate strategies that employ combinations of suitably engineered beacons that work harmoniously to enhance DP migration of particles. The synergy between multiple beacons increases the interaction range, imparts directionality, enhances migration velocity and prolongs equilibration. The versatility of the SI phenomena highlighted here suggests new possibilities for sorting and separating colloidal mixtures, targeted particle delivery, and enhancing the rate of suspension flocculation, especially in dilute suspensions where even commercial flocculants would take much longer to form colloidal aggregates.