Fluidic Metamaterials for Controlled Transport of Active Colloids

In metamaterials, one can design novel properties by tuning the links between constituent elements. Here, we leverage hydrodynamic interactions as designed links to engineer a fluidic metamaterial for non-equilibrium colloidal control. Our system consists of an active particle in a viscous fluid confined in a periodic array of posts. Controlled hydrodynamic and electrostatic interactions of the particle with posts give rise to interesting transport modes, reminiscent of those in Floquet-Bloch systems. We present a wide range of non-equilibrium transport states for various lattice structures and external field parameters. Using Brownian dynamics, we examine the robustness of transport states to thermal fluctuations and design defects. This novel system gives insight into design of new materials for smart transport of colloidal particles.