A method of fabricating a microfluidic system having microfluidic channels on a surface of a hydrophilic substrate, the method including the steps of: hydrophobizing the substrate surface; locating a mask defining the substrate surface, the mask having open areas defining the periphery of the microfluidic channels; and applying an irradiation treatment to areas of the substrate surface exposed by the open areas of the mask, said exposed areas becoming hydrophilic to therefore form said microfluidic channels.