Fabrication of 3D printed swabs in University Hospital´s: point of care manufacturing, study of mechanical properties and biological compatibility

Herein, we describe the fabrication of 3D printed swabs by using stereolithography (SLA and DLP) 3D printing involving three university hospitals. SLA/DLP allows for the fabrication of complex structures with micrometer scale resolution. The fabricated models including specimens for mechanical testing were selected and fabricated using three different 3D printers and two different biocompatible materials. The discrepancies between the fabrication in different places as well as the factors involved in the fabrication (printing parameters, post-curing, and sterilization) have been thoroughly analyzed. Mechanical testing of normalized specimens confirmed the success in the delocalized fabrication following identical protocols with only slight variations, most probably due to the different equipment employed for the sterilization step. However significant variations were observed between the resulting printed parts depending on the material/technology employed. More precisely, those materials fabricated by DLP resulted in parts with lower elastic modulus while having similar elongation at break in comparison to those fabricated by SLA. Interestingly, both fabrication approaches enabled the production of materials that retain their properties after 14 days stored at different temperatures ranging from room temperature to -18ºC. Finally, cytotoxicity of swabs extracts has been evaluated using an endothelial cell line (C166-GFP) as an in vitro model using cell viability and metabolic activity as health indicators. According to our findings, the fabrication proposed produces cytocompatible swabs with high model fidelity that can be stored at least during 14 days without any loss of the mechanical properties.