Additive manufacturing of nitinol stents for medical applications: current status and future prospects

Abstract

Additive manufacturing (or 3D printing) of Nitinol allows a tooling-free fabrication of complex device geometries with desired porosity, composition, density, near-net-shape, while requiring little post-processing. Nitinol is a metal alloy comprising of Nickel and Titanium with material properties ideal for implantable devices. It is highly sought after in the medical industry for its three key properties: (1) shape memory; (2) super elasticity; and (3) good biocompatibility. These properties of Nitinol result in the suitability of its usage in self-expanding medical stents, which are small tube-like surgical devices typically used by surgeons to unblock or widen clogged arteries to restore regular blood flow in minimally-invasive vascular surgeries. Additive manufacturing technologies such as Selective Laser Melting (SLM) have the capability to produce metallic parts with delicate geometric features, while at the same time enabling customization at lower labour cost as digitized CAD files are used for printing, in place of tooling and fixtures. In this talk, the research work conducted at the National University of Singapore Centre for Additive Manufacturing (AM.NUS) to develop complex Nitinol stents that meet medical device standards such as ASTM F2063-05 will be presented. The relationship between the 3D printing process (e.g. optimized parameters and post-processing via electropolishing) and Nitinol properties/microstructures have been investigated in this project. The results demonstrate a good feasibility of 3DPed Nitinol stents meeting regulatory requirements in future. The current challenges and future prospects on such 3DP medical devices will be described in details.

Jerry Fuh is a Professor at the Department of Mechanical Engineering, National University of Singapore (NUS) and the Founding Director and Advisor of NUS Centre for Additive Manufacturing (AM.NUS), Singapore. He is a Fellow of SME and ASME and a PE from California, USA. Dr. Fuh has devoted himself to the research of Additive Manufacturing (AM) processes or 3D Printing (3DP) since 1995. He and his colleagues have established the NUS’s AM/3DP research programme focusing on biomedical applications and set up an advanced 3DP laboratories through several major research & development grants with industrial collaborations. In 2005, he received the IES Prestigious Engineering Achievement Award for the work on “Development of Rapid Prototyping Technologies for Precision and Biomedical Engineering” from the Institute of Engineers, Singapore (IES) in recognition of outstanding engineering skills which have made notable contributions to progress engineering in Singapore. He has published over 350 technical papers in advanced manufacturing and design, and supervised over 80 graduate students with 58 are PhD students. He also serves in more than 11 refereed journals as Editor, Associate Editor or Editorial Board Members related to design, manufacturing and AM/3DP.