Continuous digital light processing (cDLP): Highly accurate additive manufacturing of tissue engineered bone scaffolds: This paper highlights the main issues regarding the application of Continuous Digital Light Processing (cDLP) for the production of highly accurate PPF scaffolds with layers as thin as 60 μm for bone tissue engineering

Highly accurate rendering of the external and internal geometry of bone tissue engineering scaffolds affects fit at the defect site, loading of internal pore spaces with cells, bioreactor-delivered nutrient and growth factor circulation, and scaffold resorption. It may be necessary to render resorbable polymer scaffolds with 50 μm or better accuracy to achieve these goals. This level of accuracy is available using Continuous Digital Light Processing (cDLP) which utilizes a DLP® (Texas Instruments, Dallas, TX) chip. One such additive manufacturing device is the envisionTEC (Ferndale, MI) Perfactory®. To use cDLP we integrate a photo-crosslinkable polymer, a photo-initiator, and a biocompatible dye. The dye attenuates light, thereby limiting the depth of polymerization. In this study we fabricated scaffolds using the well-studied resorbable polymer, poly(propylene fumarate) (PPF), titanium dioxide (TiO ₂) as a dye, Irgacure® 819 (BASF [Ciba], Florham Park, NJ) as an initiator, and diethyl fumarate as a solvent to control viscosity.