The present invention relates to a microchannel (7) formed at the interface of two layers of material (8, 9), at least one of the two materials being a substrate (9). A volume of the microchannel (7) contains a film (10) of polymer fixed by covalent bonding to the substrate layer, said film of polymer being formed from a hydrogel material susceptible to undergoing changes in volume under the action of an external stimulus. The hydrogel polymer is chosen from those which are sensitive to changes in temperature, light, electrical field or pH. The invention further relates to the method for producing the microchannel according to the invention.