A method for fabricating a microfluidic device where first and second substantially flat platens are provided. Multiple substantially planar, substantially metal-free, adhesiveless polymer device layers, including at least one stencil layer defining a microfluidic channel penetrating through the entire thickness of the stencil such that the channel is bounded laterally by a stencil layer, and bounded from above and below by surrounding device layers to define an upper channel surface and a lower channel surface are provided. The device layers are stacked between the first platen and the second platen and controllably heated according to a heating profile adapted to form a substantially sealed adhesiveless microfluidic device wherein each upper channel surface remains distinct from its corresponding lower channel surface. The resulting microfluidic device has high inter-layer bond strength while preserving the integrity of the channel(s) defined in the stencil layer(s).
