Adhesives for Medical Devices

There is diverse range of medical devices in use in today’s times varying from a Q-tip to huge diagnostic machines. And in the assembly of all these medical devices, adhesives are playing an increasing role as fastening agents over traditional systems.

Kinds of Adhesives used in Medical Devices

Adhesives that go into the medical device industry can be grouped under three categories such as pressure-sensitive, non-structural and structural adhesives with each category fulfilling specific needs of clients. A brief of each is given as follows:

Structural: The adhesives that provide maximum strength, structural adhesives comprise epoxies in single or double parts, urethanes or acrylics. They are normally used to fasten difficult to bond together substances including rubbers, plastics and metals or applications that need to bear heavy loads. No need is required for detailed surface preparation. The applications include bonding instruments used in surgical procedures, fastening plastic soles to the cast boot bottoms and many more which conventionally would have needed nails, rivets or screws to be used. The most important kind of adhesive used in this category comprises the Cyanoacrylate Adhesives which can be either light cured or moisture cured.

Non-structural: This category comprises of contact aerosol, hot melts and gasket and rubber adhesives besides others. There is no chemical curing involved in these; instead bonding takes place by physically attaching of the adhesive. These are used in applications that do not involve load bearing. For example, hot melt adhesives that fasten on cooling solvent and so on. A couple of examples where hot melt adhesives are used is to bond wood to fabric or metal or plastic to seat cushions of a wheelchair thus eliminating the need for riveting or stitching.

Pressure-sensitive: The viscoelastic attribute of the pressure-sensitive adhesive (PSA) gives it its functional strength. It is widely used for uneven surfaces as the viscous nature of the adhesive allows it flow into the crannies and nooks of the substrate augmenting the area of contact and also to create a mechanical bond. The bond strength can be controlled by choosing the right family of adhesive from among the acrylic, silicone, synthetic rubber, hydrogel and so on. This enables the user to obtain a large amount of flexibility. One of the main application of this adhesive is with respect to blood glucose evaluating strips wherein the varied layers are bonded and sealed together easily and speedily. Other applications include surgical drapes or dressings used as first aid for addressing cuts and bruises. One major difference of this adhesive from the other two is that it does not involve attachment of the two substrates at the same time. It can be spread on to one surface at time of manufacture and can be bonded to the other surface with great ease on application of pressure.

Superiority of Adhesives for Medical Devices

These adhesives form a strong bond without the need for drilling holes into the substrate. Enhanced durability and uniform distribution of stress over the bonded surface is guaranteed. Time saving, cost-effective, flexibility of design, clean production environment are just some of the many advantages offered by these adhesives over mechanical techniques of bonding in medical devices.