A comparative study of the structural-mechanical and porosity characteristics of multi-structure vascular scaffolds

TL;DR

This study compares how different manufacturing methods affect the structure and mechanical properties of vascular scaffolds made from stainless steel.

Contribution

The study systematically compares three manufacturing processes to reveal how they influence scaffold structure and mechanical performance.

Findings

Stamped scaffolds (S3) showed the highest radial support force and tensile strength compared to knitted and woven scaffolds.

Pore size and metal coverage were found to be decoupled across different manufacturing processes.

Woven scaffolds (S2) exhibited intermediate mechanical properties that varied with mesh count.

Abstract

The geometry of vascular scaffolds is a critical determinant of their clinical performance. However, the decoupled control over structural parameters (e.g., pore size, pore shape, and metal coverage) by different manufacturing processes (e.g., knitting, weaving, and stamping) and their systematic effects on mechanical properties remain unclear. This study aims to systematically compare multi-structured scaffolds fabricated by three distinct processes within a unified testing framework, revealing the intrinsic “process-structure-property” relationship. We designed and fabricated three series, totaling eight types, of tubular scaffolds from 316 L stainless steel: the S1 series (weft-knitted integrally formed), the S2 series (woven and rolled, with four mesh gradients: 30, 60, 90, and 120 mesh), and the S3 series (stamped and rolled, with three stamping-stretching ratios). Image analysis was employed to quantitatively characterize the pore area, pore shape (aspect ratio, circularity), and metal coverage of all scaffolds. Subsequently, their axial compression, axial tension, and radial support properties were systematically evaluated using an electronic universal testing machine. The results demonstrate that the different manufacturing processes successfully created a scaffold library with highly diverse structural parameters. he pore area spanned a wide range (from 0.22 mm² to 5.10 mm²). The S3 series (stamped structures) exhibited significantly anisotropic rhombic pores (aspect ratio 1.47–1.69), whereas the S1/S2 series featured near-isotropic elliptical/square pores (aspect ratio < 1.1). A core finding was the lack of a direct correlation between pore size and metal coverage across the series, confirming that structural parameters can be decoupled through different processes. Mechanical testing revealed that the S3 series exhibited the highest radial support force (peak force > 130 N), axial tensile strength (peak force up to 2447.75 N), and Apparent Compressive Stiffness (up to 135.36 N/mm). Conversely, the S1 (weft-knitted structure) showed the lowest stiffness and highest compliance (Apparent Compressive Stiffness 1.91 N/mm). The mechanical properties of the S2 (woven structures) were intermediate and varied systematically with increasing mesh count.

Figures