PDMS-based artificial lung membranes with enhanced permeation to overcome the bottleneck in CO2/O2 selectivity

Artificial lung membranes are the heart for extracorporeal oxygenation. Hereinto, the nonporous PDMS-based membranes have excellent biocompatibility, and also isolation ability to both blood and harmful matters. Nevertheless, their CO2/O2 selectivity, in the conventional cases using pure-oxygen sweeping stream, is not enough to accomplish sufficient CO2 removal in balance with O2 addition. In this work, the oxygenation mode using oxygen-enriched stream, faithfully based on the permeation mechanism, is established to overcome this bottleneck. To neutralize the negative impacts caused by lowering oxygen content and its partial pressure, PDMS-based composite membranes with ultra-thin selective layer to enhance mass transfer have been fabricated successfully. The experiments manifest that the selective layer, on the basic condition that the composite structure is stable enough to make surface modification and realistic utilization, is decreased to 376 nm on the porous substrates. O2 and CO2 permeation rates through the ultimate membrane samples have been enhanced to 502 GPU and 4117 GPU, respectively. In this instance, the essential oxygenation could be sustained with O2 partial pressure less than 446 mmHg in the sweeping stream. The minimum membrane area for a common treatment case is 0.05 square meters. Once the membrane area is increased to 0.18 square meters, the sterile air after purification could be directly used for oxygenation. In comparison to the oxygenation devices being used currently, membrane area can be saved by about 90 %, which is highly significant to reduce the injuring influence on blood cells. All in all, the artificial lung membranes with ultra-thin PDMS coating layer have promising future in realistic utilization.