On the effect of design and fabrication parameters on mechanical performance of 3D printed PLA scaffolds

Tissue engineering is responsible for developing biological substitutes that restore, maintain or improve tissue function. A solution to achieve this is to implant scaffolds on the affected tissue. These support structures will be responsible for cell protection, oxygenation and nutrition, while supporting mechanical loads during the regeneration process. They should also be biodegradable in order to be gradually replaced by healthy tissue. From the available scaffolds manufacturing techniques, fused filament fabrication has been used recently. This technique does not use organic solvents and has the ability to produce complex geometries. In this paper the influence of manufacturing parameters was assessed. Different temperatures, extrusion speeds, filament offset distances and layer thicknesses were tested and their effect analyzed regarding scaffold morphology and mechanical properties. By decreasing the filament offset distance, three different scaffolds porosities were obtained, increasing the mechanical properties. Combining higher printing temperatures with slow extrusion speeds and low layer thickness, a maximum yield stress of 28 ​MPa and apparent compressive modulus of 942 ​MPa were obtained. With these preferred parameters, two different manufacturing schemes and geometries were tested. While using a double layer printing scheme one obtains an average of 70% increase in mechanical properties, using a staggered configuration can decrease mechanical properties up to 84%.