Microfluidic devices and systems incorporating cover layers

A microfluidic device, comprising:

• a body structure comprising at least a first microscale channel network disposed therein, the body structure having a plurality of ports disposed in the body structure, each port being in fluid communication with one or more channels in the first channel network;
• and
• a cover layer comprising a plurality of apertures disposed through the cover layer, the cover layer being mated with the body structure whereby each of the apertures is aligned with at least one of the plurality of ports;
• wherein each of the body structure and the cover layer separately comprises at least a first surface, the plurality of ports being disposed in the first surface of the body structure, and the plurality of apertures being disposed in the first surface of the cover layer, the first surface of the cover layer being mated to the first surface of the body structure such that the apertures align with and are in fluid communication with the ports;
• and
• wherein the first surface of the body structure and the first surface of the cover layer are planar.