Quality And Properties
The quality controls in place in the medical device
industry are stringent for reasons of patient
safety. The whole industry relies on timely
communication between suppliers and manufacturers.
Most manufacturers require around a 2-year lead time
for a change of polymer.
Monitoring shelf-life of polymers is important for
performance. Tests for material performance include
gel permeation chromatography (GPC) for molecular
weight, capillary for viscosity, melt flow index for
ease of flow, differential scanning calorimetry
(DSC) for thermal transitions and qualitative
analysis, and Fourier Transform Infrared
Spectrometry (FTIR) for contamination and
Many factors can affect materials including
transport and storage conditions.
The specialist knowledge-base for this industry is
now focused in three locations in USA, Europe and
Asia, all of which are ISO13485 certified.
Sterilization procedures are designed to kill
pathogens such as bacteria and fungi, however there
can still be problems with chemical and particulate
contaminants on medical devices, which are not
removed by these methods.
Sterilization affects materials in different ways
depending on the technique, from ethylene oxide and
gamma irradiation to autoclave. The rewards are
seeing a device operational and improving the
quality of life for patients.
Approvals include good manufacturing practice and
control of materials supplies to ensure consistent
Material specification includes mechanical,
chemical, biocompatibility, electrical and thermal
properties, as well as Processibility. It is
expensive to take a new device to market because of
the cost of design and tests to obtain performance
data, as well as FDA approval.
Key performance measures include substrate adhesion,
durability and mechanical properties, thickness and
swelling in body fluids, particle and leachable
release, biocompatibility and degradation of
Blood contact polymers should not: absorb protein,
release additives into the bloodstream, carry
infection, cause clots or cancer, or provoke an
immune response or irritation.
In the past the material did not contain stabilizers
or processing aids. Now a few antioxidants have been
Current healthcare trends include minimally invasive
surgery: device developments include a
silicone-access port for multiple instruments; micro
endoscopes; and remote handgrips that simulate real
Coatings are used on medical devices for protection
and to improve biocompatibility. Coatings are
applied by dip coating, spray coating, brush, roll
Silicones are used in applications varying from
catheters to surgical instruments. Silver ions are
incorporated, which are toxic to the bacteria, by
destabilizing the cell membrane, deactivating
sulphur-containing proteins and blocking
The melt filtration of polymers is used for
catheters and balloons. This can remove more than
80% of gels and other contaminants while retaining
polymers’ inherent mechanical properties.
More advanced medical devices to perform minimally
invasive surgeries with greater precision, the
demands on polymer components and materials continue
to escalate. This is particularly evident in
vascular stent delivery and related devices.
Today’s vascular devices require catheter shafts
that are smaller in diameter with thinner walls to
reach new areas of the body with complex surgical
Thin wall polymer balloons are attached to the end
of these shafts and used to expand vascular pathways
and to deliver stents for permanent support.
Manufacturing these thin wall polymer shafts and
balloons requires advanced melt extrusion techniques
which are dependent on polymers with substantially
greater consistency and quality.
Melt filtration process improves the quality of
vascular catheters and balloon products, which will
improve clinical performance and reduce the risk of
Specifically formulated for precision catheter
components, the custom polymers feature superior
color accuracy and surface quality as compared to
traditional generic color concentrates.
New radiopaque fillers offer superior quality that
translates to improved performance at the extrusion
step of the supply chain. It allows improved yields
and thinner wall thicknesses, thereby pushing the
limits of product design.
Radiopaque fillers are added to polymers to make
catheters and other medical devices visible under
fluoroscopy or X-ray imaging. The filler affects the
degree of contrast and the sharpness of the image to
the extent that it influences the attenuation of
X-rays passing through the body and the device.