Silicon nitride membranes for filtration and separation

Semi-Permeable silicon nitride membranes have been developed using a Bosch etch process followed by a reactive ion etch process. These membranes were observed to allow air but not water to pass through them into surface micromachined, silicon nitride microfluidic channels. Membranes with this property have potential use in microfluidic systems as gas bubble traps and vents, filters to remove particles and gas partitioning membranes. Membrane permeation was measured as 1.6 X 10-8 mol/m2Pa s of helium for inline membranes at the entrance and exit of the silicon nitride microfluidic channels.

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