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Medical device manufacturers are increasingly required to demonstrate that their products are safe and effective when subjected to complex loading conditions in the human body such as when the device may experience combinations of bending, twisting and compression. Physical test methods are difficult to implement in such cases, can only consider a finite number of [...] You can download my presentation at the 2007 Cleveland Clinic Stent Summit on carotid artery stent fractures from an engineers perspective which discusses combined loading conditions, fatigue, material limits and other factors.
Direct strain measurements in AAA stent using phase shifted moire interferometry. You can download a poster I presented at the MPMD fall 2007 conference illustrating our method for characterizing Nitinol material behavior for the design and validation of medical implants. You can download the brochure for this special symposium that brings together state-of-the-art developments in clinical imaging techniques, computer modeling, medical device testing and materials characterization with a focus on medical implants, their design and the Experimental Mechanics underlying device interaction with the human body. Phase shifted moiré interferometry is used to measure full-field strain during uniaxial tension and four point bend loading of nitinol test samples. Differences between global and full field measurements reveal the effects of localized transformation behavior. Results for two heat treatments of commercially available superelastic Nitinol are presented for tests conducted under controlled temperature conditions. [...] An overview of the typical in-vitro test methods used to characterize the performance of Nitinol stents is presented. Characterization requires a consistent definition and understanding of radial force as well as a consideration of the sensitivity of the various methods to friction, fixture compliance, material uncertainty and other experimental factors. These sensitivities are demonstrated using [...] You can download a presentation of emerging transcatheter devices and technologies that I put together from the engineering design perspective that includes AAA solutions, fenestrated grafts, embolic protection devices, vena cava filters, stents, closure devices coronary sinus devices and percutaneous heart valves and repair technologies. There is no excerpt because this is a protected post. A series of phase shifted moiré interferograms showing a NiTi dogbone experiencing increased tensile loading. The two images on the right exhibit clear Luders bands. You can download our brief paper describing our use of moire interferometry to measure properties of superelastic Nitinol for the reliability assessment of medical devices. The 6F LifeStent NT is an implantable self-expanding nickel titanium alloy (Nitinol) stent. The stent is manufactured from small diameter Nitinol tubing and is loaded into a delivery catheter for placement/deployment into a vessel. The stent is based on a helical design which offers a wide range of performance advantages when compared to stents with circumferential [...] |
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