Combinatorial processing including stirring is described, including defining multiple regions of a substrate, processing the multiple regions of the substrate in a combinatorial manner, introducing a fluid into a first aperture at a first end of a body to dispense the fluid out of a second aperture at a second end of the body and into one of the multiple regions, and agitating the fluid using an impeller at a second end of the body to facilitate interaction of the fluid with a surface of the substrate.