Nitinolis a nearly equiatomic metal alloyof nickel and titanium with unique properties, including superelasticity or pseudoelasticity and shape memory.
Superelasticity means nitinolshows great elasticity under stress and can snap back to its shape when pressure is released.
Nitinol’ssuperelastic properties allow medical devices using it to compress to a lower profile when being placed in a patient using a catheter. Implants made of nitinol such as heart valves expand to their intended size and shape at the site of implantation and remain inside the patient, while nitinol therapy devices such as ablation catheters expand inside the body, treat targeted tissue, and then compress again for retrieval.
Shape memory means nitinol can remember its original shape and return to it when heated. This particular property has not yet been used for FDA-cleared devices inside patients.
“With an increasing trend to treat patients using minimally invasive procedures, nitinol has become a popular choice of material due to its ability to return to its original shape after being mechanically deformed or after heat is applied,” the FDA said in anitinol guidance document. “These properties are due to reversible transformations between the austenite and martensite phases, which may be temperature-induced (shape-memory) or stress-induced (pseudoelasticity). As a result, nitinol can withstand greater amounts of reversible deformations without plastic deformation than conventional metallic alloys, such as stainless steel, titanium, or cobalt-chrome alloys.”
Medical applications for nitinol include:
- Implantable cardiac devices such as replacement heart valves that can be placed using catheter delivery
- 牙科,尤其是在口腔正畸学的电线d brackets that connect the teeth. “Sure Smile” dental braces are an example of its application in orthodontics.
- Endodontics, mainly during root canals for cleaning and shaping root canals
- In colorectal surgery, the material is used in various devices for reconnecting the intestine after a pathology is removed.
- Stentsand stent retrievers, such as theJohnson & Johnson Embotrap device for removing blood clots(thrombectomy) in ischemic stroke patients
- Orthopedic implants
- Wires for marking and locating breast tumors
- Tubing for a range of medical applications
- Ablation catheter tips
- Mechanical actuation to fight muscle atrophy (in research at Harvard)
- Dissolvable devices (in research at MIT)
- Synchron’s catheter-placed Stentrode brain-control-interface implant
How did nitinol get its name?
The name “nitinol” comes from the metals nickel and tItanium plus “NOL” for Naval Ordnance Laboratory. That’s the U.S military explosives testing facility (now known as the Naval Surface Warfare Center) in White Oak, Maryland, where nitinol was developed. Fun fact: The former NOL facility in White Oak is now the FDA’s headquarters.
More nitinol know-how fromMedical Design & Outsourcing:
- Medical nitinol manufacturing: How this nickel-titanium alloy is made for medical devices
- Medical nitinol processing: How NiTi is turned into wire, tubes and sheets for devices
- How Medtronic uses nitinol to improve the structure and effectiveness of heart devices
- What’s next for nitinol tubing?
- Understanding nitinol implant design and manufacturing
Find more information about materials used for medical devices in ourMedical Device Handbook.
This post was originally published in 2016 and updated in 2023.
MithilaGsays
Hi, I was curious to understand what the author’s take is on the current value of the Nitinol market within the medical device industry. Additionally, how would they estimate the growth rate of nitinol based devices?
Many thanks and best regards,
Mithila