Complex behaviors of colloidal particles under a one-dimensional solute concentration gradient: Unravelling three-dimensional information from one-dimensional experiments

We investigate diffusiophoresis of polystyrene particles under a one-dimensional electrolyte concentration gradient. Even though the salt concentration field is set up in a relatively simple configuration, the response of particles to the solute distribution is governed by a variety of factors, such as the particle surface-electrolyte interaction and particle sizes, as well as the surface properties and shape of the microfluidic channel. We use a dead-end pore geometry to show, both experimentally and theoretically, different behaviors of charged particles that can emerge through a one-dimensional solute concentration gradient and the influence of pore dimensions, pH, and surface properties of particles and channel.