Applications - Silicones

Silicones for Medical Engineering

Silicones and other silicon compounds are widely used in medical engineering. They are suitable for external use and, because they are physiologically safe, for a range of short term implants. Some medical applications are illustrated in the following diagrams:




Silicone rubber is used as dental impression compound. It can make exact impressions of teeth because of its flowable-to-pasty consistency. It also serves as a modeling compound for making highly accurate false teeth (see also the experiment “Room temperature curing two-component silicone rubbers”).	The tube of this respirator is made of silicone rubber. It ensures good elasticity and resistance to external influences in the clinic.	A silicone coating on the inside of this leg bandage is very good at stopping it from slipping on the skin.




Moisture-sensitive substances are protected during storage by encapsulating them in silicone resins. The outer skin dissolves only on contact with gastric acid, and releases the active ingredient. Equally, suitably encapsulated active ingredients can be implanted in the body, where they release the drug to the body over a long time period.		In insulin pumps (above), the diaphragms and tubes consist of ELASTOSIL^® LR liquid silicone rubber whereas the inside of the bandage has been given a non-slip coating of silicone fabric (below center).

Aside from the applications illustrated, silicones are used in prostheses, artificial joints, tubes, catheters, and seals in medical appliances. They still have a smooth surface after repeated use, and their elasticity is hardly impaired even after multiple sterilizations.

Worldwide, there are over a million dialysis patients who have to be connected up to an artificial kidney, or dialyzer, three times weekly for several hours. Their blood is washed in the dialyzer. During this process, the blood and a carbonate-containing solution are circulated countercurrently at the dialyzer membrane. Molecules that should be eliminated by way of the urine are smaller than the blood protein molecules and diffuse through the membrane. As a rule, the dialyzer membrane consists of a polyester fabric onto which a silicone seal is injection-molded. ELASTOSIL^® LR 3003/60 has proved to be especially suitable for this purpose.

The tubes for the hydraulic section of dialyzers are also generally made of silicones.

By virtue of their unique thermoplastic processing properties and the absence of known harmful effects, the elastic GENIOMER^® product family offers many potential applications in innovative medical engineering – for example, for catheters.