Self-deployable origami stent grafts as a biomedical application of Ni-rich TiNi shape memory alloy foil

This paper describes the design, manufacturing and properties of a new type of stent graft, the origami stent graft. Unlike conventional stent grafts which consist of a wire mesh stent and a covering membrane, the new origami stent graft is made from a single foldable foil with hill and valley folds. The Ni-rich titanium/nickel (TiNi) shape memory alloy (SMA) foil made by the newly developed ultrafine laminates method was used in order to produce the stent graft. The pattern of folds on the foil was produced by negative photochemical etching. The deployment of the stent graft is achieved either by SMA effect at the body temperature or by making use of property of superelasticity. A number of prototypes of the stent graft, which are the same size as standard oesophageal and aortal stent grafts, have been produced successfully. It was demonstrated that the stent graft deploy as expected.