Perfusion manifold assembly

A first drop 23 protruding from a first fluid port on a first mating surface 10 may be brought into contact with a second fluid droplet 22 protruding from a second fluid port in a microfluidic device 16. Upon contact, fluid may flow from a fluid source, through the first fluid port, and then into the second fluid port of the microfluidic device. A region surrounding the first fluid port may resist wetting and be hydrophobic. Surfaces may comprise hydrophilic regions, or geometric features such as a ridge, mount, gasket or depression to retain or confine droplets. The drop-to-drop connection or coupling may reduce the chance of bubbles becoming trapped during connection of ports of substrates. A perfusion manifold assembly may allow perfusion of a microfluidic device, such as an organ on a chip microfluidic device, comprising cells that mimic cells in an organ of the body; using valves.