Fine outer blood filter bag encloses coarser bag - within transparent casing of peripherally welded plastic foils

摘要

Two rectangular transparent plastic foils (1,2) are welded round their common periphery to form a flat casing wtih an inner cavity (4) and terminating in studs holding short blood inlet and outlet tubes (5,10). Within the casing are a pair of filter bags. The inner bag (6) directly receiving incoming blood has a coarse filter mesh, e.g. 200 microns, and the outer bag enclosing the first bag, a finer mesh e.g. 40 microns. The bags are peripherally welded together, while the casing foil welds sealingly enclose the blood feed tubes (5,10). ADVANTAGE - Inexpensively made filter has low capacity, needing min. amt. of blood for wetting before filtrations starts.