PULM12: Numerical Investigation of 3D-Shaped Oxygenator Membrane Performance on the Example of an Implantable Artificial Lung

Abstract

Purpose of study: A novel approach for oxygenator design is using additively manufactured 3D membrane structures called triply periodic minimal surfaces (TPMS). Their advantages over current hollow fibre membranes (HFM) are arbitrary housing geometries and the possibility of local variation. In our study, we design a TPMS-oxygenator on the example of an individual lung implant for the right lung’s upper lobe. We evaluate its performance in-silico and investigate if local variation of membrane geometry can lead to optimized device perfusion and gas-transfer. Methods: The available space for implant design was derived from generic imaging data (cf. Fig1: a). A reduced order model (ROM) for computational fluid dynamics was developed to spatially resolve gas-transfer and flow. Afterwards, the model was validated on experimental data. One instance of an isotropic membrane and one with locally modified flow resistances were simulated evaluating gas-transfer rates and residual volume (Vres) using wash out simulations. Results: The validation of the ROM showed rRMSE values for gas-transfer and pressure loss all below 10%. The local variation of membrane geometry led to a significant improvement of implant perfusion and gas-transfer rates, reducing residual volume by 7.4% and increasing O2-transfer by 13% (cf. Fig1: b). Summary: 3D membrane technology can overcome limitations of HFM, which makes its use for individualized oxygenators conceivable. As shown in this numerical analysis, especially the possibility of local membrane variation leaves space for an effective device optimization. Still, absolute gas-transfer rates of TPMS-membranes lack behind HFM due to higher diffusion resistances. Future advancements in manufacturing technique with smaller membrane thicknesses and wall distances can lead to competitive TPMS-membranes.Figure 1. Implant design and numerical results