High Throughput Omnidirectional Printing of Tubular Microstructures from Elastomeric Polymers

This study introduces a high-throughput coaxial “omnidirectional printing” approach for fabricating perfusable elastomeric microtubes with microscale lumen and thin walls suitable for tissue engineering and organ-on-a-chip use. Using a coaxial needle mounted to a bioprinter, the authors extruded a photopolymerizable citrate-based elastomer prepolymer (outer phase; PICO or POMaC) around a thermoresponsive Pluronic F127 fugitive core (inner phase), printed the tube paths into a Pluronic support bath (or onto patterned substrates), UV-crosslinked the elastomer, and then removed the Pluronic by cooling and perfusion to yield hollow tubes. By applying a designed experiment (DOE) across key process parameters (e.g., flow rate, inner:outer flow ratio, needle height, print speed, UV energy), the team tuned tube inner diameter (~350–550 µm) and wall thickness (~40–60 µm) and adjusted mechanical behavior to approximate native rat femoral vessel explants. The platform enabled rapid manufacturing of complex biomimetic geometries (e.g., cochlea-like spirals and glomerulus-like stochastic networks) and scalable integration into a 96-well plate organ-on-a-chip format with gravity-driven perfusion. To add controlled permeability, femtosecond laser ablation was used to drill microholes (~10–20 µm) through tube walls, significantly increasing small-molecule transport. Finally, endothelial cells (HUVECs and human glomerular microvascular endothelial cells) were successfully seeded to line tube lumens, supporting the use of these structures as perfusable vascular-like scaffolds for engineered tissues and high-throughput OoC devices.