3D printed auxetic stents with re-entrant and chiral topologies

Abstract

The mechanical performance of the medical stent is crucial and of key significance to the dependability and reliability of the stent-plaque-artery system. In this study, an auxetic stent, namely, re-entrant chiral auxetic (RCA) is proposed. Two types of stent (RCA-X and RCA-Y) are proposed. The RCA stents are designed through a periodic distribution of two dimensional (2D) RCA cells along both the circumferential and axial directions. A set of polyimide specimens were 3d printed using Multi-Jet Fusion (MJF) process. The compressive properties of the 3d printed stents were experimentally examined, while the tensile properties were numerically investigated. Results showed that the RCA-X stent revealed a remarkable radial expansion (i.e. auxetic features) of approximately 50% while the RCA-Y stent showed radial expansion of 16.7% . Despite the auxetic features of the compressed stents, asymmetric deformation patterns were resulted in the case of the RCA-X while uniform patterns were resulted in the case of the RCA-Y. The FE models were further employed to examined the effects of number of unit cells along the circumferential direction on the auxetic features. The auxetic features of the developed stents could be controlled by adjusting the geometric parameters of the RCA’s cell and number of cells along the circumferential direction. The promising properties of the RCA stents might sheds the light on the design auxetic stents for practical clinical applications.

Design and analysis of three-dimensional chiral metamaterials for enhanced torsional compliance

“…The concept of chiral metamaterials was then extended to three-dimensional (3D) periodic microarchitectures, exhibiting compression-twist behavior through rigid cubical nodules and deformable ribs [19]. These 3D chiral metamaterials were further developed to enable 3D auxetic [20][21][22], twisting [23], and multistability behaviors [24]. Combining 3D chiral and anti-chiral structures resulted in various deformation mechanisms, including uniform spatial rotation, compression-shearing, and compression-shrink deformations [25].…”

Compressive properties of a modified re-entrant chiral auxetic structure (MRCA) under uniaxial quasi-static loading

“…Auxetic structures are a unique class that reveals negative values of Poisson's ratio (NPR) as results of their counterintuitive deformation behavior. Under uniaxial stretching or compression, auxetic cellular structures reveal lateral expansion or contraction, respectively [10][11][12][13][14][15]. Compared to the traditional materials/structures, it was stated that the auxetic feature (i.e.…”