Fastening & Assembly Solutions & Technology July 2012

FAST JULY 2012
ADHESIVES IN MEDICAL DEVICES
High performance
bonding and sealing for
medical devices
Medical devices demand the highest level of quality and reliability. FAST discusses the adhesive
materials used in their manufacture which must be biologically inert, corrosion and temperature
resistant and have the durability and strength to perform flawlessly under a variety of conditions
Choosing the best assembly method
can be an exacting design task. This
is especially true when joining dissimilar
materials and when bonding certain plastics.
Frequently, materials with the best
engineering properties for sterile medical
applications are the most difficult to join.
For these difficult-to-bond substrates and
for many other medical devices, adhesives
provide the optimum – indeed often
the only – assembly method.
In selecting an adhesive it is important
to look at the entire assembly process,
including the preparation of substrates
and the dispensing and curing of the adhesive.
The process must be controllable
and consistent to comply with the myriad
of regulations governing the manufacturing
process.
Often the limitations of the process
considerations placed on the adhesive’s
properties will narrow the choice significantly.
But the correct choice enables
Either UV or cyanoacrylate adhesives are used
on balloon catheters as the adhesive is under a
high peel load when the balloon is inflated
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medical device manufacturers to speed
product development and manufacturing
cycles, typically for disposable-, sterileand
non-sterile reusable devices.
Single, multiple and non-sterile
In order to meet the ISO 10993 regulatory
requirements for bio-compatibility,
all elements of disposable devices,
including adhesives, must resist the sterilisation
process used by the device manufacturer.
Typical applications include:
fluid and drug delivery sets, catheters,
infusion products, syringes, hypodermics,
injectors and cardiovascular & cardiopulmonary
surgical devices.
Sterile reusable devices may be used a
number of times and are re-sterilised each
time. Examples of these products include
surgical instruments, endoscopes, laparoscopes
and arthroscopes. The introduction
of polymers able to withstand repeated
exposure to autoclaving temperature has
greatly expanded the number of different
sterile reusable devices now available.
The stainless steel cannula is
bonded to the polycarbonate hub
using a UV acrylic
There are many medical products however
where bio-compatibility is not an
issue. These products include orthopaedic
and rehabilitation equipment such as
wheel chairs, braces, hearing aids and
prosthetic devices as well as imaging,
monitoring and measuring equipment.
Non-sterile reusable devices can be bonded
with standard adhesives, not specifically
designed for medical device manufacture.
Chemical bonding
Mechanical fastening, insert moulding,
thermal bonding and solvent welding –
they all have merits but also many shortcomings
that can be addressed by adhesive
bonding. The ability to join different
material, such as thermoplastic, thermoset
plastic, elastomer and metal, is a very
important advantage of adhesive bonding.
When compared to other methods adhesives
offer design advantages, speedy
assembly, increased production efficiency
and in many cases increased production