Design News for Mechanical and Design Engineers

How is the market for medical plastics changing?

The first uses of plastics in the medical field was disposables. Now we’re doing a lot in high-performance materials for reusable items like surgical instruments, which are repeatedly autoclaved and reused.

What’s making it possible for plastics to replace metal products?

One factor is the popularity of color-coded instruments. Anodized aluminum instruments have been color-coded, but after three or four high-pressure steam cleanings, they’re pretty much bare aluminum.

There are half a dozen plastics that hold up well to pressurized steam at 274F. We put pigment materials in the plastics, so the color can’t be washed off. We’re also putting carbon fiber reinforcements in the materials. That also gives you high stiffness.

In the materials that meet the needs of autoclaving and chemical resistance, we offer 48 colors. Color is used for identification. Instead of reading inscriptions that can be hard to see, surgeons can simply say 'give me the purple one.’ Colors can also differentiate one company’s products from another.

Colors are also used for trays and other products that are used in a host of medical applications. But in these applications, light weight is more important than color coding. White is still very popular for trays.

Now that plastics are in these applications, how are they evolving?

If you take an x-ray, metal instruments are easy to see, while plastics don’t show up well. In applications where people want to see the materials in x-rays, we put radiological pacifiers in the material. That’s very helpful in the instances where surgical instruments are left in the patient.

On the flip side, there are applications where the surgeon wants to see the bones, so plastic devices that let x-rays through are very beneficial. With plastics, you can put in different additives to fit very specific needs.

Are any new applications starting to see growth?

The thermoplastic resin suppliers are being pulled into more implantable applications as new technologies call for more metal replacement. The industry in general has been very conservative in approaching these opportunities due largely to liability issues. While Ensinger does not offer materials for permanent implant, we do have some materials that are suitable for temporary implant up to 30 days. We are able to do this by testing resin and shapes to the biocompatability requirements outlined in the ISO 10993 test matrix. We continually see new niche application requirements that we are supporting by offering new materials with reinforcing fillers such as carbon fibers, antimicrobial systems, alloys or radio pacifiers.