This paper reports the first use of cold plasma deposition of polymerizable monomers for the fast, cost-effective and easy fabrication of buried air microchannels. A new method named 'plasma polymerization on sacrificial layer' (PPSL) is presented. It consists in the direct polymerization of tetramethyldisiloxane (TMDS) on a photopatterned sacrificial layer. Channels are formed with only one lithographic mask and without any etching or bonding process. The use of polymerized TMDS allows rapid creation of capillarity-driven flow systems with the channel width ranging from 4 to 700 νm without pillars. Channels are characterized and successfully tested. Capillary forces draw water, as well as aqueous solution into the channel from the inlet reservoir to the outlet one, avoiding the need of microfluidic connectors with the surrounding environment. Filling of the capillaries is very fast. It reaches the initial velocity of 4.4 cm s-1 with the geometries and water used here. In addition, PPSL easily allows the building of transparent channel networks directly on processed electrochemical or electromagnetic components. An example of one such integrated fluidic microelectromechanical system (MEMS) is described.