Magnetically Steerable Auxetic Stents With Body‐Temperature Actuation via Nonplanar and Conformal 4D Printing

ABSTRACT

Vascular stents are essential for treating coronary artery disease. This study presents a magnetically steerable 4D‐printed auxetic stent manufactured using a sustainable nonplanar printing approach designed to reduce material waste and post‐processing with a tailored poly (carbonate urethane) (PCU) shape‐memory polymer. The conformal printing improves geometric fidelity and reduces material waste compared to planar 3D printing, which requires significant sacrificial supports (> 9×) for tubular designs. Two magnetic integration strategies were shown: localised magnetic collars printed at both ends of single‐material stents and a continuous inner magnetic PLA layer integrated with the auxetic structure. Shape‐memory characterization showed temperature‐dependent recovery for both designs: at 37°C the PCU‐collar configuration recovered ∼28%, whereas the dual‐material stent recovered ∼10%; at 44°C both reached ∼67%; and at 50°C recovered to ∼87% and ∼78%, respectively, with recovery time decreasing from ∼30 s (37°C) to ∼16 s (50°C). The dual‐material stent has higher compression and bending stiffness but lower recovery and durability with repeated cycling. Magnetic guidance demonstrated noncontact positioning and retrieval of stents, revealing a practical design trade‐off between magnetic controllability and shape‐memory performance and establishing a scalable method for low‐waste multifunctional polymeric stent manufacturing.