# Enhancing radial strength and expansion uniformity of iron-based vascular scaffolds: a numerical and experimental investigation on topological optimization

## TL;DR

This study improves the performance of iron-based vascular scaffolds by optimizing their design to ensure uniform expansion and reduce mechanical failure risks.

## Contribution

A dual-factor topological optimization strategy is introduced to enhance expansion homogeneity in iron-based scaffolds.

## Key findings

- Optimized scaffolds showed 19.2% reduction in maximum principal strain and 19.0% in equivalent plastic strain.
- Radial strength of optimized scaffolds reached 260.07±4.68 kPa, comparable to CoCr alloy stents.
- Improved expansion homogeneity reduces coating cracking and corrosion risks.

## Abstract

Thin-walled iron-based bioresorbable scaffolds have garnered significant research interest due to their exceptional mechanical properties and favorable biocompatibility. However, current thin-walled iron-based bioresorbable scaffold designs exhibit non-uniform expansion, leading to coating cracking, malapposition, postoperative in-stent restenosis (ISR), and localized pitting corrosion that compromises mechanical integrity.

This study proposed a dual-factor optimization strategy prioritizing expansion homogeneity through finite element analysis and experimental validation. We systematically modulated the strut width and thickness, as well as the crown radial width in nitrided iron scaffolds, evaluating their mechanical and expansion performance.

It showed that the optimized (OPT) scaffold maintained comparable radial recoil and foreshortening to the original design while demonstrating significant reductions in maximum principal strain (19.2%) and equivalent plastic strain of expand (19.0%).

In vitro expansion experiments confirmed substantially improved expansion homogeneity, while its radial strength (260.07±4.68 kPa) exceeded that of magnesium/polymer scaffolds, achieving parity with CoCr alloy stents. Enhanced expansion homogeneity mitigates coating fracture risks while maintaining clinically sufficient support.