Additive manufacturing of superelastic NiTi braided metamaterials: an innovative strategy for engineering minimally invasive vascular medical devices

Additive manufacturing of superelastic Nitinol (NiTi) braided metamaterials is demonstrated in this study, enabling the creation of a wide variety of concepts for personalized vascular medical devices. Engineering contributions include the algorithmic design of lattices and woven structures, which can be adjusted to anatomical surfaces and whose mechanical properties can be controlled by design, enabling functional gradients of stiffness and transitions between lattices and wovens, as well as the creation of fully-connected braided structures achieved in a single printing step. Additionally, the optimized laser powder bed fusion (LPBF) of NiTi powders, combined with a set of post-processing techniques, including chemical etching and electropolishing, enables the manufacture of algorithmic designs and further contributes to achieving the superelasticity required for the crimpability, manipulation and usability of minimally invasive transcatheter devices (MITDs). Several types of MITDs prototypes, including stents, transcatheter aortic valve replacements, customized shape clot retrievers for thrombectomy, tapered flow diverters, braided bifurcations, and fenestrated stents, among other possibilities, may be manufactured with this new approach as illustrated by means of proof-of-concept prototypes. These advances and designs are expected to contribute to personalized approaches for cardiovascular and neurological surgery, once the analyzed key challenges are overcome, as also discussed.