Laser Additive Manufacturing of Anti-Tetrachiral Endovascular Stents with Negative Poisson’s Ratio and Favorable Cytocompatibility

Abstract

Laser additive manufacturing (LAM) of complex-shaped metallic components offers great potential for fabricating customized endovascular stents. In this study, anti-tetrachiral auxetic stents with negative Poisson ratios (NPR) were designed and fabricated via LAM. Poisson’s ratios of models with different diameters of circular node (DCN) were calculated using finite element analysis (FEA). The experimental method was conducted with the LAM-fabricated anti-tetrachiral stents to validate their NPR effect and the simulation results. The results show that, with the increase in DCN from 0.6 to 1.5 mm, the Poisson ratios of anti-tetrachiral stents varied from −1.03 to −1.12, which is in line with the simulation results. The interrelationship between structural parameters of anti-tetrachiral stents, their mechanical properties and biocompatibility was demonstrated. The anti-tetrachiral stents with a DCN of 0.9 mm showed the highest absolute value of negative Poisson’s ratio, combined with good cytocompatibility. The cytocompatibility tests indicate the envisaged cell viability and adhesion of the vascular endothelial cell on the LAM-fabricated anti-tetrachiral auxetic stents. The manufactured stents exhibit great superiority in the application of endovascular stent implantation due to their high flexibility for easy maneuverability during deployment and enough strength for arterial support.

Editorial for the Special Issue on Laser Additive Manufacturing: Design, Processes, Materials and Applications

“…This Special Issue article covers a wide range of forming materials, including steel [1,9] and other iron-based alloys [11], magnesium alloys [3], titanium alloys [6,12], copper alloys [7], aluminum alloys [13], composites (e.g., CF/PA12 [4], copper/titanium-coated diamond [14]) and, in particular, metallic multi-materials (e.g., NiTi/CuSn10 [2], copper/steel [7]) and 4D-printing materials (e.g., NiTi shape memory alloys [2,15], smart materials for soft interactive hydrogel [5]). et al [12] investigated types of Ti-6Al-4V (TC4) materials with different porosities fabricated via L-PBF using different printing parameters.…”

“…The design of laser additive manufacturing covered in this Special Issue includes the structural design (e.g., the negative Poisson's ratio endovascular stents [1], the multimaterial heterostructures [2]) and the material design (e.g., the in situ synthesis of a novel alloy [3] and composite modification [4]).…”

“…Chen et al [1] reported that anti-tetrachiral auxetic stents with negative Poisson's ratios (NPR) were designed and fabricated via LAM. The cytocompatibility tests indicate the envisaged cell viability and adhesion of the vascular endothelial cell on the LAMfabricated anti-tetrachiral auxetic stents.…”

Experimental validation of auxetic stent designs: three-point bending of 3D printed Titanium prototypes

“…Self-expanding stents derived from topologically optimized auxetic unit cells demonstrate adaptive stiffness, favorable flexibility and conformability to deter stent mal-apposition and inappropriate stent expansion ( 5 ). Conventional stent manufacturing methods are not suited to fabricate vascular stents derived from auxetic unit cells due to their intricate morphology ( 6 ). Additive Manufacturing (AM) techniques are perfectly suited to fabricate personalized stents with morphological complexity, with increasing research interest shown for the fabrication of AM vascular stents in the last decade ( 7 – 9 ).…”

“…Jiang et al ( 15 ) employed polyjet AM techniques with photocurable resins to generate stents comprising of auxetic tubular lattice unit cells. Chen et al ( 6 ) employed laser powder bed fusion (LPBF) AM technology to assemble stents comprised of anti-tetra-chiral auxetic unit cells with 316l stainless steel powder raw material. Xiao et al ( 16 ) applied high-resolution projection micro-stereolithography AM technique to generate stents with planar anti-chiral NPR unit cells, followed with gold nano thin film coating applied in post-processing steps to enhance radial strengthening.…”