Direct 3D printing of thin-walled cardiovascular stents with negative Poisson's ratio (NPR) structure and functional metallic coating

Abstract

To realize sufficient radial supporting capacity, currently proposed 3D-printed polymer vascular stents often have thicknesses >400 μm, much thicker than the ASTM criteria of ∼25–177 μm, which would bring the potential risk of in-stent restenosis. Here, based on high-resolution projection micro-stereolithography (PμSL) 3D printing and metal thin film deposition, we proposed the design and manufacturing of thin-walled 3D-printed composite cardiovascular stents with sufficient radial supporting ability. Firstly, negative Poisson's ratio (NPR) microlattice structure was designed and printed as the scaffold for thin-walled vascular stent, and then sputtered with gold (Au) nano thin film through radio-frequency (RF) magnetron sputtering for radial strengthening. As a result, the composite stents realized up to ∼70% radial compressive strengthening accompanied by slightly increased toughness, and a 10%–20% stent thickness reduction. With thin film gold coating, the stent can also resist 35% radial compression deformation, and showing good cytocompatibility. Finally, composite stents with wall thickness as thin as ∼150 μm and sufficient radial support ability was successfully realized. This work provides a potential solution to overcome the dilemma that thin wall thickness and sufficient radial support capacity cannot be achieved at the same time, and inspires more medical device applications based on novel 3D-printed mechanical metamaterials.