Pressure assisted multi-syringe single nozzle deposition system for the fabrication of heterogeneous scaffolds

This research focuses on the development of a layered based novel fabrication methodology for three-dimensional tissue scaffolds with heterogeneous structure of varying concentrations of drug molecules and/or multiple bio-materials. In this research, in addition to the function of scaffolds as supporting structures, the scaffolds are developed that are capable of releasing proteins and growth factors locally for improved angiogenesis and morphogenesis, and hence decreasing recovery time. A pressure assisted multi-syringe single nozzle deposition system has been developed for the fabrication that can overcome the limitations of conventional layered-based fabrication techniques. A custom designed nozzle has been fabricated to converge the flows from two syringes into a small mixing chamber. An automatic system for pressure control has been proposed to fabricate tissue scaffolds using hydrogel based bio-materials with enclosed drugs or proteins. The presented work also details the fluid model for pressure requirements and material volume flow for a biomaterial. Sodium alginic acid is selected as scaffold bio-material and cross-linked with calcium chloride solution for gelation. The designed system is able to fabricate 3D structures from hydrogels with varying concentration of drug microspheres depending on the design requirements. Scaffolds are successfully fabricated with different nozzles of diameter 100mum, 150mum and 200mum with varying porosities.;Keywords. Heterogeneous scaffold, tissue engineering, multi-syringe single nozzle deposition, automated pressure control system (APCS).