Design and functional testing of a novel balloon-expandable cardiovascular stent in CoCr alloy produced by selective laser melting

Abstract

Selective Laser Melting (SLM) is a promising technology for the manufacturing of patient-specific medical implants, due to the intrinsic potential in the realization of one of a kind parts with complex geometries. The present work analyses the production of balloon-expandable stents in cobalt-chromium alloy with a novel mesh which is realized using an industrial SLM system. The stent mesh optimized for the SLM process, was designed, produced, finished and functionally tested by balloon expansion. Electropolishing was used to clean the stent surface from sintered particles and to improve the surface finish. Roughness measurements were carried out on stents both in the as-built and the electropolished conditions, while mechanical properties were evaluated by tensile testing with dogbone specimens, produced with the same parameters of the stents and having comparable dimensions. Finally, the expansion behaviour of the CoCr stents, both in as-built and electropolished conditions, was assessed using a balloon catheter and measuring the diameter variation as a function of inflation pressure. The results confirm that SLM produced stents can be successfully balloon expanded without damaging their characteristic mesh.