Medical Design Briefs: 2021 Technology Leaders - 6

TECHNOLOGY LEADERS Electrical Connectors/Wires/Cables
Exploring Medical Applications of
Ultra-Fine Nitinol Wire
A
s the name alludes to, nitinol is a
nickel-titanium alloy known for
its shape memory and super -
elastic characteristics. Shape
memory refers to nitinol's ability to
undergo deformation at one temperature,
then recover its original, under
formed shape upon heating above its
transformation temperature.
Super elasticity occurs at a narrow temperature
range just above its transformation
temperature; in this case, no heating
is necessary to cause the underformed
shape to recover. The material exhibits
enormous elasticity, some 10-30 times
that of ordinary metal. It was initially discovered
in 1968 in a search for mining
materials. Still, it took decades for nitinol
to become useful in the marketplace due
to the difficulties encountered in its processing
and manufacturing.
In fact, nitinol's many uses have mostly
all been realized since the mid-1990s
when its usefulness in a broad range of
applications derived from it being a
shape memory alloys and its' superelastic
properties. It is now widely used for
many medical components, including
reinforcement braiding and coiling for
catheter tubing and shafts, braided and
formed stents, formed retrieval baskets,
and many other applications. The shape
memory makes it an excellent candidate
for many in-body applications such as
catheter reinforcement and braided
stents. Nitinol is also used for these medical
devices because it is biocompatible,
meaning it is compatible with the hu -
man body and will, therefore, not be
harmful to human tissue.
Other materials that are not biocompatible
can result in issues such as blood
clotting when used for similar applications.
Nitinol is generally produced in
large cast ingots and can be subsequently
processed all the way down to ultrafine
wires that are only a fraction of the
size of a human hair. The final stages of
the entire process are called wire drawing
and require precision control in order
to maintain physical and mechanical
properties.
6
Nitinol is now widely used for many medical components, including formed stents. (Credit: Ulbrich)
The shape memory makes it an excellent candidate for many in-body applications such as catheter reinforcement.
(Credit: Ulbrich)
Ultra-fine wire is very small diameter
(thickness) wire that is held to incredibly
tight tolerances. Fine wire products are
engineered with cutting-edge online
gauging to deliver outstanding dimensional
precision and reliability. Nitinol is
produced at Ulbrich in fine and flat wire
forms with micro-scale diameter and
widths and is then meticulously wound to
guarantee tolerance consistency and
ensure downstream performance. Nitinol
wire in this form is a great choice for medical
devices that may be introduced into
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the body to perform surgical procedures
or treat diseases, and their mechanical
properties play a significant role in the
selection of metal for their manufacture.
Applications for Nitinol Wire
Medical device manufacturers should
also decide whether braid-enforced or
coiled-enforced catheters are the best
choice for their application. Many
OEMs are now choosing to use nitinol
for coiled catheters in especially sensitive
surgeries or other applications
Medical Design Briefs 2021 Technology Leaders

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Medical Design Briefs: 2021 Technology Leaders

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