<p>Preterm neonates are susceptible to respiratory distress syndrome (RDS) due to their underdeveloped lungs and require mechanical ventilation. Microfluidic blood oxygenators (MBOs) are a suitable alternative due to their small priming volume and their potential to reduce iatrogenic effects of ventilation. Current MBOs use lithographic fabrication that limits their manufacturability due to scalability and integration issues. Additive-manufacturing has been recently explored to overcome fabrication challenges, but has its own limitations in realizing scalable thin-membrane devices with high degree of channel patency. This work presents a new hybrid additive-manufacturing strategy for artificial lungs, by combining extrusion printing of sacrificial isomalt scaffolds with spin-coating of thin polydimethylsiloxane membranes. It eliminates the use of synthetic polymers or toxic solvents, yielding complete channel patency and biocompatibility. Using this scalable process, oxygenators with 11 alternating blood/gas layers separated by thin (121 µm) membranes were manufactured, achieving complete channel patency and a 0% rejection rate. In vitro evaluation showed reduced form-factor while achieving a high oxygen-transfer efficiency of 184 mL O₂ min⁻¹ m⁻². Furthermore, the performance metrics of the devices were evaluated against the clinical requirement, substantiating their ability to support a 1 kg neonate with RDS, achieving 1.73 mL O₂ min⁻¹ oxygen uptake at 30 mL min⁻¹ blood flow rate, with 8.6 mL priming volume and offering pumpless operation.</p><p></p>