Microfluidic cartridges or devices for serum separation and blood cross-match analysis are provided. The devices may include a serum separation subcircuit alone or in combination with a solute mixing subcircuit. The serum separation subcircuit promotes on-cartridge clotting of a blood sample and manipulates the flow of the separated serum sample for subsequent cross-match analysis with a second blood sample, for example. The solute mixing subcircuit includes at least two intake channels, one for a whole blood sample from, for example, a blood donor and the other for the separated serum sample from, for example, a transfusion recipient. The solute mixing subcircuit further includes a serpentine mixing channel conjoined to a downstream channel. Under vacuum generated by a conjoined finger pump, the two input streams fill the serpentine mixing and downstream channels due to capillary action, enabling visualization of an agglutination reaction.