Toward 3D printed microfluidic artificial lungs for respiratory support

Microfluidic artificial lungs (mu ALs) are a new class of membrane oxygenators. Compared to traditional hollow-fiber oxygenators, mu ALs closely mimic the alveolar microenvironment due to their size-scale and promise improved gas exchange efficiency, hemocompatibility, biomimetic blood flow networks, and physiologically relevant blood vessel pressures and shear stresses. Clinical translation of mu ALs has been stalled by restrictive microfabrication techniques that limit potential artificial lung geometries, overall device size, and throughput. To address these limitations, a high-resolution Asiga MAX X27 UV digital light processing (DLP) 3D printer and custom photopolymerizable polydimethylsiloxane (PDMS) resin were used to rapidly manufacture small-scale mu ALs via vat photopolymerization (VPP). Devices were designed in SOLIDWORKS with 500 blood channels and 252 gas channels, where gas and blood flow channels were oriented orthogonally and separated by membranes on the top and bottom, permitting two-sided gas exchange. Successful devices were post-processed to remove uncured resin from microchannels and assembled with external tubing in preparation for gas exchange performance testing with ovine whole blood. 3D printed channel dimensions were 172 mu m-tall x 320 mu m-wide, with 62 mu m-thick membranes and 124 mu m-wide support columns. Measured outlet blood oxygen saturation (SO2) agreed with theoretical models and rated flow of the device was 1 mL min-1. Blood side pressure drop was 1.58 mmHg at rated flow. This work presents the highest density of 3D printed microchannels in a single device, one of the highest CO2 transfer efficiencies of any artificial lung to date, and a promising approach to translate mu ALs one step closer to the clinic. Development and testing of a small-scale 3D printed microfluidic artificial lung (mu AL) fabricated via UV light based vat photopolymerization and a custom polydimethylsiloxane photopolymer resin.