Embedded Fused Filament Fabrication of Thermoplastics for Biomedical Applications

Utilizing material extrusion three-dimensional printing methods, particularly fused filament fabrication (FFF), allows for the creation of complex architectures. Nevertheless, FFF-fabricated structures often suffer from inadequate mechanical properties and elevated surface roughness. In this study, we developed an embedded FFF (e-FFF) approach to produce thermoplastic products with enhanced mechanical characteristics and improved surface quality. This approach was achieved through the development of a thermostable yield-stress fluid made from fumed silica particles and sunflower oil. By tuning the rheological properties of the support bath, thermoplastic filaments were effectively supported in a molten state throughout printing. Biocompatible and biodegradable polycaprolactone (PCL) was selected as the exemplary thermoplastic polymer in this work. Filaments, single-layer sheets, and tensile test samples were printed to fine-tune the printing parameters, assess surface morphology, and certify mechanical properties of structures printed by e-FFF. To demonstrate the potential biomedical applications of the approach, an orbital implant model was designed by numerical simulation for evaluating the mechanical integrity. Then, the orbital implant was printed and measured to confirm the effectiveness of the proposed e-FFF approach. Lastly, cells were successfully incubated on the PCL implant, which was affixed to a mock orbital fracture to confirm that patient-specific orbital implants could be fabricated.