Nitinol is a nearly equiatomic metal alloy of nickel and titanium with unique properties, including superelasticity (also called pseudoelasticity) and shape memory.
Superelasticity/pseudoelasticity means nitinol shows great elasticity under stress and can snap back to its original shape when pressure is released.
Nitinol’s superelastic 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. For example, some catheter-delivered implants are designed to expand to their pre-formed shape at body temperature for permanent placement.
A promising application of nitinol’s shape memory properties is under development by heart failure startup Adona Medical, which is working on a heart shunt device that can be adjusted for variable flow rates.
“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 a nitinol 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.”
Nitinol medical devices include:
- Implantable cardiac devices, such as the frames of replacement heart valves that can be placed using catheter delivery (Medtronic’s Harmony valve is one example) or Abbott’s implantable clips to repair leaky heart valves
- Stents and stent retrievers, such as the Johnson & Johnson Embotrap device for removing blood clots (thrombectomy) in ischemic stroke patients and self-expanding pediatric stents under development
- Cardiac ablation catheters such as those developed by Medtronic, Affera and Biosense Webster
- For renal denervation (RDN) systems that treat hypertension, such as Medtronic’s Symplicity Spyral radiofrequency catheter and the needles that deliver alcohol in Ablative Solutions’ Peregrine catheter
- Synchron‘s catheter-placed Stentrode brain-control-interface implant
- Peripheral intervention devices such as LimFlow’s first-of-its-kind system for avoiding amputations due to chronic limb-threatening ischemia
- Dentistry, especially in orthodontics for wires and 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, nitinol is used in various devices for reconnecting the intestine after a pathology is removed.
- Orthopedic implants
- Surgical robotics, such as this prototype for pediatric brain tumor procedures
- Wires for marking and locating breast tumors
- Tubing for a range of medical applications
- Dissolvable devices (in research at MIT)
- Mechanical actuation to fight muscle atrophy (in research at Harvard)
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 from Medical 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
- Nitinol machining and finishing for medical 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
Notable nitinol supply chain updates
- March 2024: Montagu to buy Johnson Matthey Medical Device Components for $700M
- January 2024: Confluent invests to expand ATI nitinol melting infrastructure
- October 2023: Resonetics closes $900M nitinol deal and rebrands Memry and Smart Materials
- December 2022: Johnson Matthey opens medical nitinol facility in Mexico
- August 2022: Confluent Medical expands Costa Rica manufacturing footprint for nitinol, complex catheter production
- February 2022: Confluent Medical Technologies closes majority investment from TPG Capital
- April 2021: Resonetics to expand manufacturing in Costa Rica
- January 2021: Confluent Medical inks nitinol supply deal
Find more information about materials used for medical devices in our Medical Device Handbook.
This post was originally published in 2016 and most recently updated in April 2024.
MithilaG says
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