3D printing of silk powder by Binder Jetting technique

This study describes for the first time the development of a silk powder-based 3D printing formulation that is compatible with Binder Jetting, a commercial additive manufacturing (AM) technique. The dynamic and bulk properties of the precursor powder were measured, including particle sizing, shape, flow energy, and compressibility, and the relationships between these properties, particle flow and printability were investigated. We used two different types of silk powder, super fine silk powder (SFSP) with an average particle size of 5 µm and fine silk powder (FSP), average particle size of 20 µm, and found that FSP provided good flow, spreadability and printability with polyvinyl alcohol (PVA) used as the solid binder. An optimized SP/PVA powder formulation was developed and successfully printed into intricate structures with a resolution as high as 200 µm. The printed green samples were analysed thoroughly to determine the printing performance, resolution, porosity, and mechanical strength. The compressive modulus of the printed SP/PVA parts reached 3 MPa, which was comparable to that of some ceramic printed parts. An effective infusing and immersion post-crosslinking method was developed and found to enhance the water stability of the printed constructs, making the printed parts suitable for potential load-bearing biomedical applications.