Numerical Evaluation of a Zero Poisson's Ratio Structure in µ-3D-Printed Self-Expanding Nitinol Stents

Stenting is a minimally invasive treatment used in managing peripheral artery disease (PAD). However, clinical challenges persist, including in-stent thrombosis and restenosis, primarily driven by axial foreshortening or elongation and suboptimal balance between radial stiffness and flexibility inherent to conventional stent designs. This study proposes an innovative arrow-shaped geometry exhibiting zero Poisson's ratio (ZPR) behaviour for 3D-printed self-expanding Nitinol stents. The complete stent deployment process was modelled using finite element analysis (FEA), including radial crimping and subsequent expansion to enable systematic parametric investigation while accounting for µ-3D printing constraints. Response surface methodology (RSM) rigorously evaluated mechanical performance, defining peak stress, chronic outward force (COF), radial resistive force (RRF), and foreshortening (FS) as constraint and objective functions within the optimisation framework. The optimised ZPR stent achieved favourable performance: extremely low foreshortening (|FS| ≤ 0.12%), representing outstanding axial stability compared with previously reported self-expanding stents, and a well-balanced radial response with ~50% higher radial strength than positive Poisson's ratio (PPR) structures, while 16.67% lower than negative Poisson's ratio (NPR) counterparts. These results highlight the ZPR stent's capability to minimise axial deformation while maintaining adequate radial support, highlighting substantial potential for precise, stable deployment in PAD applications.