Fig. 1: Fabrication process flow of multilayer polymer micro-structures.

a (Left) Reversible sealing of dead-end channels embedded in a PDMS mold by a PDMS membrane. Typical dimensions are h = 10–50 µm, e = 10–50 µm, and w = 50–1000 µm. (Right) Transverse view evidencing the solvent pervaporation flux through the PDMS membrane when the channel is filled by a dilute ink (blue). b (Left) schematic 3D view of the pervaporation-induced flow for a single channel (blue arrow). (Right) corresponding schematic pervaporation-induced growth of a material (red). c (Left) removal of the PDMS stamp from the membrane. (Right) the resulting micro-materials are rigid enough to be handled manually, as shown by the SEM image of a simple PVA-CNT beam in which we made a knot (width 150 µm, thickness h = 30 µm). d Alignment of a second structured PDMS mold with the material still embedded in the first block (red). Filling of the channel using a photo-curable polymer (black) makes it possible to fabricate a second layer after UV polymerization (MIMIC process). e (Left) SEM transverse view of an NOA81/PVA-CNT composite bilayer, the total thickness of the structure is H = 115 µm. (Right) Perspective SEM view of the same micro-structure, the width of the main channel is 150 µm