Development of a Coaxial Melt Extrusion Printing process for specialised composite bioscaffold fabrication

The increased popularity of Additive Fabrication (AF) processing techniques in recent years has catalysed its application in a wide range of research disciplines. The use of Solid Freeform Fabrication (SFF) as a technique for the synthesis of functional biomaterial scaffolds for tissue engineering implants epitomises the level of specialisation, as well as the diversity in application, that is possible through the utilisation of an additive approach. While these scaffolds can provide ideal cellular interfaces and be impregnated with growth factors and electrically conducting nanomaterials, the processing itself provides only minimal flexibility with respect to the number of composite materials which can be implemented to reach these targets of function. In this work, a method for the Coaxial Melt Extrusion Printing (CMEP) of multifunctional, conductive and biocompatible co-fibres is presented. This allows for the coupling of two materials into an encapsulated core and shell configuration, and their subsequent extrusion into complex scaffold and path-oriented architectures. Selective Laser Melting was implemented to produce a high resolution stainless steel 316L coaxial extrusion nozzle, exhibiting diameters of 300μm/900μm for the inner and outer nozzles respectively. Following post processing, this component was employed as the cornerstone technology for the development of a computer numerically controlled coaxial extrusion printing system.