Medical

Plastic devices of all types have become vital in the medical industry. Products range from disposables (medical supplies, drug delivery devices, ointments, etc.) to non-disposables and packages to containers to body parts. Packaged drugs include premeasured single-dose disposable units. The diversified properties and behaviors of plastics have developed into an important market for plastics.

Plastic applications are very diversified ranging from band-aids to parts of the heart. Many examples exist in addition to those being reviewed.

1.Abiomed (Danvers, MA) is the manufacturer of the self-contained artificial heart. Of the six patients who received the grapefruit-sized plastic and titanium heart, three remain alive (2003).

2. Developments have found certain plastics existing in the environment of living tissues.

3.The heart valve that is often used in surgery to correct heart deficiencies was a contribution to medicine. In order for it to be successful it required ingenuity in design that would function as a replacement for the mitral valve and to perform as well as the one replaced long enough to justify the risk involved in the operation. It also included using a bioplastic material that would function in the highly complex environment of the human circulatory system without being degraded and without causing harm to the circulatory system.

4. Many developments occur in the area of implants that include the use of plastics. Examples include pacemaker, surgical prosthesis devices to replace limbs, use of plastic tubing to support damaged blood vessels, and work with the portable artificial kidney.

5.There are applications based on the membrane qualities of plastics. They can control such things as the chemical constituents that pass from one part of a system to another, the electrical surface potential in a system, the surface catalytic effect on a system, and in some cases the reaction to specific influences such as toxins or strong radiation.

6. Polyelectrolytes plastics are chemically active. They have been used to make artificial mechanical power muscle materials. They create motion by the lengthening and shortening of fibers made from the chemically active plastic by changing the composition of the surrounding liquid medium, either directly or by the use of electrolytic chemical action. It is no a competitor to thermal energy sources, but it is potentially valuable in detector equipment that would be sensitive to the changing composition of a water stream or other environmental flow situation.

7. There is the application of extruded high- and low-pressure plastic balloons used in angioplasty catheters. Use of these balloons has extended into many applications such as other catheters (dilatation, heat transfer, laser, cryogenic, etc.), photodynamic therapy devices, drug delivery devices, etc.

8. Plastics in bioscience have potential to be used for mechanical implants in living systems (includes animals and plants) where they can serve as repair parts or as modifications of the system.

9. Kidney applications involve more than the mechanical characteristics of potential plastic use. The kidney machine consists of large areas of a semi-permeable membrane, a cellulosic material in some machines, where the kidney toxins are removed from the body fluids by dialysis based on the semi-permeable characteristics of the plastic membrane. Different plastics are being study for use in this area, but the basic unit is a device to circulate the body fluid through the dialysis device to separate toxic substances from the blood. The mechanical aspects of the problem are minor but do involve supports for the large amount of membrane required.

10. Surgical implants are essentially plastic repair parts for worn out parts of the body. It is possible to conceive of major replacements of an entire organ such as a kidney or a heart by combining the plastic skills with tissue regeneration efforts that may extend life. This is used to time the heart action. Extensively used are plastic corrugated, fiber (silicone or TP polyester) braided aortas.

11. Different customized developments exist and are being used. An example is a porous (foam type) ultrahigh-molecular-weight polyethylene (UHMWPE) that is an FDA-compliant material. Its porosity and pore size can be adjusted per the end-users' requirements. The porosity is uniform in all diree (X, Y, Z) axes, which is vital to constant liquid flow in filtration and separation. It is already used in a wide range of medical and laboratory filtration and separation applications by providing customizing processing where chemical purity of the material is maintained (no additives are used). UHMWPE is a chemically resistant, long-chain polymer of ethylene with an extremely high molecular weight of 3.1 million amu or above. Because of its high molccular weight, the polymer maintains abrasion resistance and strength even when it is made porous for filtration or separation applications. The porous form, which can be pleated, is easily handled in manufacturing. It can be precision skived into films as thin as 0.002 in. (skiving consists of shaving off a thin film layer from a large block of solid plasdc, usually a round billet).

Doctors with long, intensive training as basic scientists make them uniquely suitable as product designers. They become involved in designing new products that in turn could require the plastic industry in developing new/modified plastics. With all this action in developing medical products and devices the FDA usually requires approval that takes time.

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