Abstract: The formation of a barrier layer within individual channels or cavities of a microfluidic device is described. The barrier layer is effected through a gas phase deposition process, desirably implemented in a plasma environment using a gas plasma reactor. Judicious selection of a precursor compound used within the gas plasma reactor can provide for generation of a layer on the individual surfaces. Desirably the surface or barrier layer is generated through the chemical adsorption of a metalloid oxide such as a silicon oxide layer on the surface of the individual channels or cavities.