Abstract: An exchanger for oxygenating blood includes a casing having walls and a cavity, sheet material with first and second ends covering distal edges of the walls, and a cover extending over the cavity to sandwich the first and second ends of the sheet material between the cover and the edges of the walls. The cover is melted into the sheet material and the distal edges of the walls. In another embodiment, a blood oxygenator includes a first compartment having a closed casing divided by a folded sheet of membrane material forming a first blood chamber and a first gas chamber. The casing has first and second manifolds in fluid communication with the first blood chamber. A second compartment is interconnected with the first compartment and has a closed casing divided by a folded sheet of membrane material forming a second blood chamber and a second gas chamber. The casing has third and fourth spaced apart manifolds in fluid communication with the second blood chamber.

Abstract: A method for manufacturing an exchanger includes the steps of folding sheet material in a series of pleats, placing the folded sheet material in a casing having an opening defined by walls with distal edges, covering the distal edges with end portions of the sheet material, and affixing a cover to the casing by simultaneously melting a portion of the cover and the sheet covered distal edges of the walls, and contacting the cover with the sheet material covering the distal edges of the walls. The method may also include melting a portion of the cover and/or the casing and placing the melted cover on the casing so that the melted portion contacts pleats of the sheet material, and permitting the melted material to cool and solidify and form a bond with the sheet material.