Cylindrical structure for medical application
Wu, Ya Dong.
Date of Issue2010
School of Mechanical and Aerospace Engineering
Robotics Research Centre
In order to solve the major problems of current stents, such as stent migration and stent restenosis, two new types of stent have been proposed in this project, namely origami stent graft and self-expanding braided Nitinol stent. The designs, fabrication processes and properties of new stents have been investigated for the medical application. The origami stent graft, unlike the conventional stent grafts. It does not consist of a wire mesh stent and a covering membrane, which are common in the conventional stent grafts. The new origami stent graft is made from a Nitinol (titanium and nickel alloy) sheet with 0.1mm thickness. During the fabrication process, every unit pattern was formed by pressing. After that, a patterned cylinder was shaped from a single Nitinol sheet. Lastly, heat treatment was performed, so that the deployment of stent graft was achieved by shape memory effect at the body temperature. Prototypes of the stent graft with the same size as standard esophageal had been produced successfully. The braided stent, is designed based on the existing braiding technology. The geometry of braided stent has been calculated to prove the design feasibility. Furthermore, two different designs were introduced in this part with their prototypes. In the first design, braided stent was composited by weaving a number of Nitinol strips. In the second design, several pieces of Nitinol strips were braided inside the expanding braided sleeving as an actuator. Prototypes of the braided stent based on these two designs had been produced by the author. At the end of the project, both designs can provide flexible self-expanding characteristics, and effectively eliminate the problem of stent restenosis.
Final Year Project (FYP)
Nanyang Technological University