Steering Colloids across Solute-releasing Hydrogel arrays

Hydrogels can gradually release solutes, a feature that has proven useful in the context of drug delivery applications. Utilizing microfluidic experiments and in-situ hydrogel fabrication as well as numerical simulations, we study the interplay between flow and localized solute gradients formed around hydrogel arrays. These gradients lead to the phoretic migration of colloids, and their filtration and removal. We discuss the implications of our observations for colloid transport in dissolving porous media and drug delivery to hidden targets.