Characterization of printable micro-fluidic channels for organ printing

Organ printing is a complex and challenging process in execution due to the lack of fundamental understanding of tissue and organ formation, and problems associated with giving the organ-conforming 3D shapes. One of the major challenges is the inclusion of blood vessel-like channels between layers to support cell viability in terms of nutrients and oxygen transport. Tissue scaffolds have been widely used in generation of replacement tissue by providing mechanical support and fluid nutrients, but complications with scaffold degradation and the corresponding adverse effects on extra cellular matrix still present major challenges. This paper introduces a new approach in tissue scaffolding for cellular assembly to minimize these problems. This research investigates the manufacturability of novel printable micro-fluidic channels, where the micro-fluidic channels support mechanical integrity as well as enable fluid transport in 3D. A pressure-Assisted solid freeform fabrication platform is developed with co-Axial needle dispenser unit to print hollow hydrogel filaments, which will later be used to support nutrients and oxygen transport through the printed cell assembly. The dispensing rheology is studied and the effect of material property on structural formation of hollow filaments is analyzed in this paper. Sample structures are printed through the computer-controlled system. In experiments with sodium alginate, 4% CaCI ₂-4% alginate solution combination results in the smallest core and filament diameter. In experiments with chitosan on the other hand, 3% chitosan-1% NaOH combination brings the smallest core and filament diameter.