Medical Design Briefs - August 2021 - 8

Advanced Extrusion Techniques
* Multilumen extrusion for catheters,
electric medical devices, analytical
equipment, fluid transfer, drug delivery,
and medical instrumentation.
* Geometric transitioning extrusion
applied to custom applications with
precision tolerances.
* Geometric transitioning single lumen
for custom-end assemblies, such as
accommodation of connectors, fittings,
and peristaltic pumps.
* Drug-eluting silicone extrusions that
help prevent infection.
* Foam extrusion that provide additional
cushion space.
Multilumen extrusion is suitable for catheters, electric medical devices, analytical equipment, fluid
transfer, drug delivery, and medical instrumentation. (Credit: Trelleborg Healthcare & Medical)
variety of materials. These include plastics,
such as fluorinated ethylene propylene
(FEP), nylon, PVC, polyetheretherketone
(PEEK), polytetrafluoroethylene
(PTFE), and thermoplastic elastomers
(TPE), as well as elastomers, in particular,
silicone.
Silicone is a key material for tubing in
medical devices, making it attractive for
healthcare applications, especially for
im plants. The unique characteristics of
high consistency rubber (HCR) silicones
offer an uncured, " green " strength that
allows for a variety of custom processing
techniques. Additionally, silicone is nonreactive
with other elements, odorless,
tasteless, and nontoxic, and it has good
tensile strength.
Tubing Technologies
Recent innovations and
techniques in medical tubing
manufacturing are allowing medical
device manufacturers to meet patients'
needs more effectively. Tubing technologies
include the following:
* High-precision, microextrusion, and
thin-walled tubing for minimally invasive
surgical devices.
* Platinum-cured silicone for use in im -
plants.
* Multicomponent extrusion featuring
radiopaque stripes for visibility in an
x-ray or fluoroscope.
* Reinforced and kink-resistant tubing
used to keep fluid paths open.
* Extruded ribbon and film used in
diaphragms to support seals in devices
such as pacemaker generator housings.
* Jacketed wires and cables used to
power implantable heart pumps.
* Twisted extrusions for applications in
which implanted power or sensing
cables require strain relief from
repeated flexing and bending, as with
pacemaker leads.
* Custom profiles used to seal housing
assemblies and repair heart valves.
* Bump tubing applied to plastics and
Silicone is a
key material
for tubing
in medical
devices, making
it attractive
for healthcare
applications,
especially for implants.
(Credit: Trelleborg
Healthcare & Medical)
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Cov
elastomers, including silicone.
* Bonded or overmolded stops
typically added to peristaltic
pumps for infusion,
internal feeding, laboratory
equipment, di -
ag nostic equipment,
and fluid transfer.
* Formed extrusions used to
fit tortuous anatomy or spiral
shapes that might be
used to soften contact within
the bladder.
Applications and Advancements
Different processing options have led
to groundbreaking ways of producing
tubing. When customers partner with
medical device component manufactures
that utilize the latest capabilities
and technologies, they can create solutions
that optimize the performance and
usability of medical devices.
For example, in cardiac catheterization,
wider, thinner tubes make the procedure
less invasive. Inserting a narrow
micro-extruded catheter into a large
blood vessel that leads to the heart
enables doctors to examine how well the
heart is working.
These more advanced new tubing
technologies can potentially meet medical
device manufacturers' goals in areas
such as miniaturization, wearability, and
patient care. Multilumen extrusion
allows for intricate design, more complex
shapes, and better texture in the
finished tubing. Filaments and rigid
monofilaments within the walls of the
product add reinforcement that provides
the tubing with better kink- and
crush-resistance.
The most accomplished tubing manufacturers
are now pushing the limits of
tubing size in terms of miniaturization,
individual lumen, overall cross section,
and wall thickness. Tubing with controlled
texture can eliminate the risk
and cost of additional coating processing
in some cases. Silicone is inherently
sticky, and inducing a texture on extruded
silicone can address the unwanted
tackiness of the material.
HCR silicone's strength in its unvulcanized
state allows for highly complex
geometries in continuous extrusion
processes. For example, GeoTrans™, a
Trelleborg Healthcare & Medical pro -
cess, enables tool components to be
moved during extrusion to substantially
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Medical Design Briefs - August 2021

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