Evaluation of Superelastic Auxetic Structures For Medical Stents and Intrasaccular Devices

Tuesday, May 17, 2022: 4:30 PM
Sunset Ballroom (Westin Carlsbad Resort)
Ms. Duygu Dengiz , Kiel University, Kiel, Germany
Ms. Sabrina M. Curtis , Kiel University, Kiel, Germany
Mr. Lars Bumke , Kiel University, Kiel, Germany
Mr. Justin Jetter , Kiel University, Kiel, Germany
Prof. Eckhard Quandt , Kiel University, Kiel, Germany
Medical implants like stents and intrasaccular devices require structuring into complex shapes that can adapt to the natural bending curvatures of the vascular system. This study evaluates the use of super elastic auxetic structures for medical applications. Auxetic structures have a negative Poisson's ratio which allows them to have a high shape adaptation [1]. This is our motivation to use these structures for intrasaccular device designs which are a relatively new method to treat aneurysms.

Finite element modeling (FEM) resulted in five auxetic mechanical test structures that are evaluated for medical implants regarding tensile testing, deployment, and crimping behavior. Based on these results and further characterization by polarization microscopy, differential scanning calorimetry and X-ray diffraction the design of future auxetic medical devices was aided. These stents and intrasaccular implants will be fabricated in a process using photolithography, magnetron sputtering of super elastic TiNi thin-films, etching, and rapid thermal annealing [2]. Finally, 4D-MRI flow analysis characterizations to examine the blood flow behavior of auxetic stents deployed in 3D printed aneurysms models [3] are discussed.

[1] Rayneau-Kirkhope, D. Stiff auxetics: Hierarchy as a route to stiff, strong lattice based auxetic meta-materials. Sci Rep 8,(2018)

[2] Bechtold, C.; Lima de Miranda, R.; Quandt, E.: Capability of Sputtered Micro-patterned NiTi Thick Films, Shap. Mem. Superelasticity 1,(2015)

[3] Velvaluri, P., Pravdivtseva, M.S., Lima de Miranda, R., Hövener J. B., Jansen O., Quandt E. Design Characterization of Thin Film Flow Diverter Stents (FDS) Based on SMA’s: FEA, CFD and MRI Study. Shap. Mem. Superelasticity 5,(2019)

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