The Nitinol Core is a fee-for-service laboratory providing early stage design and manufacturing of biomedical devices made from advanced materials such as nitinol, Elgiloy, CoCr, MP35N, and 316LSS. Nitinol is a relatively new alloy that is being incorporated into commercial and medical applications because of its extraordinary shape memory and superelastic properties. So why is there so much interest in nitinol?
- Biocompatibility, corrosion resistance
- Super-elasticity (pseudo-elasticity)
- Shape memory effect
- Kink resistance
- Constant restoration stresses
- Physiological compatibility
Nitinol Surgical Devices
Currently, nitinol is used in the following biomedical applications: cardiovascular stents, kink resistant guidewires, minimally invasive surgical tools, and self-locking orthopedic devices. Key aspects of the advances when using nitinol are smaller devices for minimally invasive surgical techniques. Other elements of nitinol used for stent applications include radial resistive force (RRF) and constant outward force (COF).
Recent Projects Include:
- Peripheral vascular stents
- Biodegradable polymer stents
- Heart valve support frames
- Ablation stents
- Aortic stent grafts
- Orthopedic attachments
- Sutureless clip
Dave Dudzinski, BS
The Nitinol Core houses the equipment needed to overcome the particular challenges that face nitinol product designers in all phases of commercialization. Utilizing the new equipment purchased, scientist and engineers pool their talent and resources in a comprehensive, proactive, and focused approach to nitinol design that should bring new products to market within the next few years. The collaborators in the Nitinol Commercialization Accelerator (NCA) project represent some of the nation’s best expertise in the areas relative to nitinol product innovation including Case Western Reserve, University of Toledo, NASA Glenn Research Center, Norman Noble and State of Ohio Wright Project Center.Heat Treatment
- Heat treatment
- Mandrel design
- Determining the proper heat treatment parameters to achieve shape and properties
Detect and set nitinol phase transformations
- Af optimization
- Fluidized bath heat treatment operating temperatures from +50 to 700°C, with accurate temperature stability ±0.2°C.
- No heat loss when immersing devices unlike ovens and furnaces where you have to open a door.
Techne Precision Calibration Bath
The Techne FB-08 employs the principle of fluidisation of a mass of finely divided particles to provide a safe, essentially isothermal environment with a high rate of heat transfer. To achieve a state of fluidisation, a gas stream is forced to pass vertically through the bed of fine powder; chromatographic alumina (a specially refined grade of aluminium oxide). At, and above, a certain critical value of flow rate the particles become separated from each other and the whole mass behaves like a liquid.
Athermal Lasercut designs
Lasercut designs from tube or flat sheet
- Tube diameters from 0.3mm up to 10mm
- Sheet dimensions 12”x 12”
- Minimal heat affected zone (HAZ)
- Straight cuts can be made in a single pass
- Ultra fine kerf <20 microns
- Wall thicknesses < 0.7mm
- 4 axis for intricate geometrie
- Lasercut designs from tube or flat sheet
- Laser programming for complex geometries
- Lasercut fixture design for repeatability from part
The system is suitable for cutting prototypes and stents out of thin-walled tubes with any geometry up to approx. 260 mm length. The tube is held via a pneumatically driven 3 jaw chucks. Programming is normally prepared off line in ‚unwrapped 2D geometry, which is then converted in the software to the cylindrical format.
Material Processing & Testing
Material properties stress-strain behavior
- Uniaxial tensile testing material
- Radial and compressive stent testing
- Grain structure
SEM Images of Nitinol Fracture
"Shape Memory" means that the alloy can "remember" its shape; after being deformed it returns to its original shape through the application of heat. Material is tested for radial stiffness, pinch compression.