the valve module comprising first, second and third chamiel segments in the channel network, the second and third channel segments intersecting the first channel segment at an inlet end and an outlet end of the first chamiel segment, the inlet and outlet ends of the first channel segment forming inlet and outlet sides of the valve module, respectively, and a flow controller that directs flow of fluid through the first, second and third channel segments to selectively stop flow into and out of the inlet and outlet sides of the valve module when the valve module is in a closed configuration, and allowing flow into and out of the inlet and outlet sides of the valve module when the valve module is in an open configuration; first andand third channel segments in the channel network, the second and third channel segments intersecting the first channel segment at an inlet end and an outlet end of the first chamiel segment, the inlet and outlet ends of the first channel segment forming inlet and outlet sides of the valve module; and first and second pipettor elements fluidly connected to the first channel network, wherein the first pipettor element is fluidly connected to the first channel network on an inlet side of the valve module, and the second pipettor element is fluidly coupled to the first channel network on an outlet side of the valve module.

36. The microfluidic device of claim 35, further comprising one or more pressure sources operably coupled to the second and third channel segments