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Figure 7. Symphony stent, nitinol wire welded to form a closed-cell structure.
Figure 19. AVE S7 stent: balloon expandable open-cell sequential ring design with periodic peak-to-peak non-flex connections.
Figure 17. NIR stent: a closed-cell structure featuring ‘V’ flex-hinges.
Figure 18. SMART stent: self-expanding open-cell sequential ring design with periodic peak-to-peak non-flex connections.
Figure 21. BeStent: balloon expandable open-cell sequential ring design, with midstrut-to-midstrut connections and integral gold markers.
The Superelasticity of NiTinol appears to be much more physiologic compared to e.g. stainless steel.
Medical Applications http://translate.google.com/translate?hl=en&sl=de&u=http://www.memory-metalle.de/&prev=/search%3Fq%3Dnitinol%26hl%3Den%26Ir%3D
Fort Wayne Metals • Nitinol Wire Applications • Our Nitinol wire is used for many different medical and industrial applications. The table below gives some typical engineering applications for each of our standard Nitinol medical grades: • GradeApplication • NiTi#1Guidewires, stents, stylets, forming mandrels, stone retrieval baskets, orthodontic files, etc. • NiTi#2Ideal for applications that require a high loading and unloading plateau stresses at room temperature, cell phone antennae, eyeglass frames. • NiTi#4Provides the best cycling performances at 37°C at body temperature.
Nitinol uses Hall-Garcia Cardiology Associates
Nitinol • Hall-Garcia Cardiology Associates
Elastic Springback and Constancy of Stress • Nitinol’s springback or elasticity is about 10 times greater than stainless steel. • Nitinol can be designed to apply constant force or stress over a variety of shapes. A good example of this is orthodontic archwires.
Biocompatibility Nitinol is also MRI compatible because it is non-ferromagnetic with a lower susceptibility than stainless steel. • Nitinol is compatible with the human body even though nickel is toxic. Nitinol is an intermetallic compound in metallurgical sense and the bonding force of nickel and titanium is much stronger than stainless steel. • When nitinol oxidizes, which is not easy for it to do, due to the protective coatings, it forms TiO2 on the outside with no nickel on the surface. This makes it safe for contact with the human body. • Nitinol is also more stable and less corrosive that stainless steel. • Flexibility and kink resistance allows the alloy to be bent and deformed far beyond the abilities of stainless steel. Today small nitinol tubes and wires travel all throughout the body.
Elastic deployment allows complex instruments to pass through small tubes (cannulas) and into the human body, where they deploy and return to their programmed undeformed shape. Superelastic nitinol medical instruments can be deployed with the shape memory technique which works well with human bodies. After cooling the nitinol to its martensite phase it can deployed once the Af Temperature is reached, and the Af Temperature is set to about 98 degrees F. Stents are inserted to keep vessels open in the body, and they will grow larger as the vessel grows because of their flex ability and elasticity. Elastic and Thermal Deployment