Multi objective design optimization of self-expandable nitinol braided stents

Abstract

Cardiovascular stents are indispensable medical devices used to treat vessel-related issues such as atherosclerotic plaque. In the past, stents were mainly made of materials like stainless steel or cobalt-chromium alloy. However, over the last two decades, research has focused on the use of Nitinol (NiTi) due to its superior properties such as super-elasticity, biocompatibility, and strength. The aim of this paper is to optimize the design of an open-ended braided stent, subjected to radial compression, with enhanced performance. The optimization process uses Multi-Objective Particle Swarm Optimization (MOPSO), which explores three design variables, namely wire diameter, number of coils, and braided angle, to determine the optimal shape that maximizes radial pressure stiffness and radial force exerted on the vessel walls while minimizing foreshortening. The analytical model developed is compared against literature findings, and the optimization results are implemented in a finite element analysis solver and compared with existing references. The results show that the optimized design using MOPSO enhances the stent’s average radial force and radial pressure stiffness by 28% and 40% respectively, while decreasing foreshortening by nearly 5%. The results demonstrate the feasibility of MOPSO for optimizing braided NiTi stents and the use of FEM for validating optimized designs.