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Diffusiophoretic manipulation of particles in a drop deposited on a hydrogel

Diffusiophoretic manipulation of particles in a drop deposited on a hydrogel

We published an article in Soft Matter about the diffusiophoretic manipulation of particles in a drop deposited on a hydrogel.

In this paper, we report an experimental study on the manipulation of colloidal particles in a drop sitting on a hydrogel. The manipulation is achieved by diffusiophoresis, which describes a directed motion of particles induced by solute gradients. By letting the solute concentrations for the drop and the hydrogel be different, we control the motion of particles in a stable suspension, which is otherwise difficult to achieve. We show that diffusiophoresis can cause the particles to move either toward or away from the liquid-air interface depending on the direction of the solute gradient and the surface charge of the particles. We measure the particle adsorption experimentally and rationalize the results with a one-dimensional numerical model. We show that diffusiophoretic motion is significant at the lengthscale of a drop deposited on a hydrogel, which suggests a simple method for the deposition of particles on hydrogels.

Available on the editor’s website and on ArXiv.