Steel reinforced composite silicone membranes and its integration tomicrofluidic oxygenators for high performance gas exchange

摘要

Respiratory distress syndrome (RDS) is one of the main causes of fatality in newborn infants, particularly in neonates with low birth-weight. Commercial extracorporeal oxygenators have been used for low-birth-weight neonates in neonatal intensive care units. However, these oxygenators require high blood volumes to prime. In the last decade, microfluidics oxygenators using enriched oxygen have been developed for this purpose. Some of these oxygenators use thin polydimethylsiloxane (PDMS) membranes to facilitate gas exchange between the blood flowing in the microchannels and the ambient air outside. However, PDMS is elastic and the thin membranes exhibit significant deformation and delamination under pressure which alters the architecture of the devices causing poor oxygenation or device failure. Therefore, an alternate membrane with high stability, low deformation under pressure, and high gas exchange was desired. In this paper, we present a novel composite membrane consisting of an ultra-thin stainless-steel mesh embedded in PDMS, designed specifically for a microfluidic single oxygenator unit (SOU). In comparison to homogeneous PDMS membranes, this composite membrane demonstrated high stability, low deformation under pressure, and high gas exchange. In addition, a new design for oxygenator with sloping profile and tapered inlet configuration has been introduced to achieve the same gas exchange at lower pressure drops. SOUs were tested by bovine blood toevaluate gas exchange properties. Among all tested SOUs, the flat design SOU withcomposite membrane has the highest oxygen exchange of 40.32 ml/min m². Thesuperior performance of the new device with composite membrane was demonstrated byconstructing a lung assist device (LAD) with a low priming volume of 10 ml. The LAD wasachieved by the oxygen uptake of 0.48–0.90 ml/min and the CO2 release of1.05–2.27 ml/min at blood flow rates ranging between 8 and 48 ml/min. This LAD was shownto increase the oxygen saturation level by 25% at the low pressure drop of 29 mm Hg.Finally, a piglet was used to test the gas exchange capacity of the LAD invivo. The animal experiment results were in accordance within-vitro results, which shows that the LAD is capable of providingsufficient gas exchange at a blood flow rate of ∼24 ml/min.