Improving mechanical properties of porous calcium phosphate scaffolds by constructing elongated gyroid structures using digital light processing

Abstract

The present study reports the manufacturing of a novel type of porous calcium phosphate scaffolds with elongated gyroid structures using digital light processing (DLP), in order to offer significantly enhanced mechanical properties. In particular, solid camphor was employed as the diluent, in order to offer sufficiently low viscosity at high solid loading for conventional layer-by-layer DLP process. Four types of porous CaP scaffolds with different percent elongation (%EL = 0, 20, 40, and 60) were manufactured, and their porous structures and mechanical properties were characterized. All porous CaP scaffolds showed that CaP walls were elongated along the z-direction, while the degree of pore elongation increased with an increase in the designed %EL. Owing to the use of controlled processing parameters, such as layer thickness and exposure time for layer-by-layer photocuring process, and carefully designed debinding process, the photocured layers could be completely bonded together with high densification after sintering at 1,200 degrees C for 3 h. Such elongation of a gyroid structure offered significantly enhanced mechanical properties compressive strengths of 4.33 +/- 0.26 MPa and 11.51 +/- 1.75 MPa were obtained for the porous CaP scaffold with the %EL of 0 and 60, respectively.