Development of a novel direct powder screw extruder for 3D scaffold printing of PCL-based composites

Polycaprolactone (PCL) has emerged as a prominent biomaterial for fabricating scaffolds in tissue engineering applications via 3D printing. However, the common commercial form of PCL is typically observed in powder or pellets, which may not be conducive for deployment in traditional 3D fused deposition modeling (FDM) printers that utilize filaments. Moreover, most additive biomaterials that are mixed with PCL commonly exist in a powdered form. Consequently, the primary drawback of the conventional FDM printing method arises from the requirement to convert into a filament form. This research addresses the abovementioned constraint by developing and optimizing a novel design of a direct powder mini-screw extruder (DPSE) through numerical modeling analysis. The cost-effective DPSE printer head enables the printing of not only pure PCL but also PCL-based composite scaffolds by utilizing a combination of PCL powder and other biomaterials such as thermoplastic polymers, hydrogels, or ceramics. Microscopy, scanning electron microscopy (SEM), and attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectroscopy are employed to characterize the morphology, surface roughness, and chemical composition of the porous scaffolds. Furthermore, other characteristics of the 3D PCL-based composite scaffolds, including wettability, mechanical properties, and cell attachment, are also investigated. The experimental study investigates the influence of printing parameters on the printed line width for each PCL-based composite. Through these investigations, this work demonstrates the high potential of the novel DPSE printer head in fabricating high-quality PCL-based composite scaffolds with minimal wastage and prolonged printability.