3D-Printed TPMS Membranes Could Make Artificial Lungs More Efficient

3D-Printed Membranes Could Make Artificial Lungs More Efficient

A team of researchers from Hannover Medical School, RWTH Aachen University, Technical University Darmstadt, and the University of Twente has developed a new approach to artificial lung membranes using 3D printing. Their work, published in Advanced Materials, suggests that triply periodic minimal surface (TPMS) architectures can move more oxygen through a smaller surface area than the hollow fiber membranes used in current oxygenators.

The study focused on replacing the bundles of tiny hollow fibers that make up conventional membrane oxygenators with a continuous TPMS lattice. The researchers modeled Schwarz Diamond unit cells with wall thicknesses between 10 and 400 micrometers, then ran computational fluid dynamics simulations to compare blood flow through the TPMS structure against a standard hollow fiber bundle.

The results were significant. The optimized TPMS design reduced stagnation regions by up to 56 percent and cut maximum blood velocity roughly in half, from 0.126 m/s to 0.062 m/s. More importantly, the best-performing configuration delivered an average oxygen transfer rate 87.8 percent higher than conventional hollow fiber membranes, while using about 44 percent less membrane surface area.

Less membrane surface area means less artificial material in contact with the patient's blood, which could reduce the risk of clotting and inflammation over time. That is a meaningful advantage for a device that sits inside the body or circulates blood through an external circuit.

The team also screened printable materials for the membrane itself. They tested MAP-PDMS, xPDMS, PorePro, and Sinterit's FlexaGrey TPU. xPDMS emerged as the strongest candidate: it can be printed directly using digital light processing into dense 100-micrometer walls, shows substantially higher oxygen permeability than the hollow fiber reference, and maintains endothelial cell viability above the 80 percent threshold required for blood-contacting applications.

To make the membrane compatible with living tissue, the researchers coated xPDMS with fibronectin and seeded it with primary human endothelial cells. The cells formed a continuous monolayer with proper cell junctions and deposited collagen IV, mimicking the natural lining of blood vessels. Gene expression analysis showed increased thrombomodulin, a sign that the cells were functioning as a healthy blood-contacting surface.

The work is still at the simulation and in-vitro stage. The researchers note that printing thin, defect-free membranes at scale, clearing enclosed channels after printing, and maintaining a stable endothelial lining under long-term blood flow remain open challenges. But if those hurdles can be cleared, TPMS-based oxygenators could improve outcomes for patients on extracorporeal life support and make lung replacement therapies more viable.