Structure-dependent gas transfer performance of 3D-membranes for artificial membrane lungs

State of the art artificial membrane lungs incorporate hollow fiber membranes. The creeping blood flow in hollow fiber bundles forms a boundary layer that represents a diffusive resistance to gas transfer. Advances in additive manufacturing allow for the fabrication of novel membrane designs that overcome this limitation. The goal of this study is fabrication and subsequent experimental evaluation of blood gas transfer of novel membrane designs based on triply periodic minimal surface (TPMS) geometries in comparison to the predominantly present hollow fiber geometry. A fabrication process was established based on a casting process with a dissolvable 3D-printed mold. Modules were manufactured containing different membrane designs: three TPMS designs, namely Schwarz-P (SWP), Schwarz-D (SWD), Schoen-G (SGY), and a hollow fiber shaped design (HFM) as reference. Each membrane consists of silicone and has a wall thickness of 800 μm. To assure comparable results, the design of the module considers matching inlet conditions, smallest membrane distance and the same gas exchange area. Gas transfer was tested in vitro under standardized conditions in accordance with ISO 7199 for blood gas exchangers. The oxygen transfer rate for TPMS geometries is at least by 26% and up to 69.8% higher than the state of the art hollow fiber design within a flow range of 20–100 mL/min.