A fluidic dispensing device includes a housing having an exterior wall and a chamber. The exterior wall has a first opening. The chamber has an interior space and has a port coupled in fluid communication with the first opening. A stir bar is located in the chamber. The stir bar has a rotational axis. A guide portion is located in the chamber. The guide portion includes a confining member having a guide opening that defines an interior radial confining surface that engages the stir bar, wherein the guide opening facilitates a radial movement of the stir bar in a direction substantially perpendicular to the rotational axis.