Diffusiophoretic transport of colloids in periodic porous media

Colloids can move in the presence of solute gradients; this phenomenon is known as diffusiophoresis. Recent studies have demonstrated the utility of diffusiophoresis in manipulating and steering colloids using simple microfluidic geometries and in the absence of any background flows. Yet, it remains a question whether diffusiophoresis could play an important role in more complex environments such as in porous media, where background fluid flows are often present. Here, combining experimental observations and numerical simulations of microfluidic channels patterned with an ordered lattice of obstacles, we study the competition between phoretic and convective migration of colloids.