Experimental Characterization and Finite Element Modeling of the Effects of 3D Bioplotting Process Parameters on Structural and Tensile Properties of Polycaprolactone (PCL) Scaffolds

In this study we characterized the process-structure interactions in melt extrusion-based 3D bioplotting of polycaprolactone (PCL) and developed predictive models to enable the efficient design and processing of scaffolds for tissue engineering applications. First, the effects of pneumatic extrusion pressure (0.3, 0.4, 0.5, 0.6 N/mm(2)), nozzle speed (0.1, 0.4, 1.0, 1.4 mm/s), strand lay orientation (0 degrees, 45 degrees, 90 degrees, 135 degrees), and strand length (10, 20, 30 mm) on the strand width were investigated and a regression model was developed to map strand width to the two significant parameters (extrusion pressure and nozzle speed;p< 0.05). Then, proliferation of NIH/3T3 fibroblast cells in scaffolds with two different stand widths fabricated with different combinations of the two significant parameters was assessed over 7 days, which showed that the strand width had a significant effect on proliferation (p< 0.05). The effect of strand lay orientation (0 degrees and 90 degrees) on tensile properties of non-porous PCL specimens was determined and was found to be significantly higher for specimens with 0 degrees lay orientation (p< 0.05). Finally, these data were used to develop and experimentally validate a finite element model for a porous PCL specimen with 1:1 ratio of inter-strand spacing to strand width.