US Patent 7252856 Blood gas syringe having improved blood barrier

A process for fabricating a water-swellable porous plastic plug is provided, the process including the steps of: providing a porous substrate having a plurality of passageways therethrough, disposing into the passageways a hydrophilic polymer, irradiating the substrate to induce cross-linking of the hydrophilic polymer, such that the polymer forms a hydrogel coating on the walls of the passageways.