Fabrication of microfluidic devices using photopatternable hybrid sol-gel coatings

UV-patternable organic-inorganic hybrid sol-gel coating was used to develop microchannel on silicon and glass wafers by photolithography processing. The sol-gel coating was formed with 3-methacryloxypropyltrimethoxysilane (MPTS) as photosensitive component and zirconium propoxide as property modifier. In order to enhance the UV light efficiency during photolithography processing for glass substrates, a thin copper layer with thickness of 100–200 nm was deposited on one side of the glass wafer. The closed microchannels were formed by bonding of two developed surface channels of compensating patterns by wafer bonding technology. The bonding material is the same as the channel body ensuring a uniform surface property for the microchannels. A thin layer of about 2 μm was applied on the developed channels by spin coating. The depth of the surface channels on each wafer is about 10–12 μm, and the height of the closed channels is therefore in the range of 22–24 μm. Different microfluidic devices such as chaotic micromixers and microsplitters were fabricated.