Steering colloids using solute gradients and flow

Controlling the motion of colloids is important in a wide range of applications, from cell sorting to filtration and water purification. Recent studies have utilized the diffusiophoretic migration of colloids due to solute gradients to manipulate and guide them. However, solute gradients next to solid surfaces also drive diffusioosmotic flows, which are often ignored. Here, combining experimental observations and numerical simulations of flow through a T-junction, we show that the coupling between diffusiophoretic migration of colloids and diffusioosmotic flows next to the solid surfaces can lead to unexpected focusing patterns.