The invention relates to a microfluidic device comprising a first plate forming the substrate and including at least one perforation and, on either side of said first plate, at several locations, a material for defining passage portions consisting, in at least one of said locations, of an activatable material varying in volume on activation, said material being disposed at said locations in an arrangement that, during a first phase and upon activation of at least one location consisting of said activatable material, transforms it from a first configuration to a second configuration, modifying a three-dimensional network corresponding, in the second configuration and depending on the selected location(s) that are activated in said first phase, to different liquid paths including passage portions in offset planes parallel to the plane of the first plate, at least on either side of said first plate, and between which at least one of said perforations is located.