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A soft revolution in healthcare: specialty foams are being applied to medical designs to create a new wave of products that benefit both patients and healthcare providers. Here's a look at how these materials are being produced and why they are so important. (Design ideas: manufacturing processes).

The partnering of medical science and industry is creating some remarkable healthcare products. In fact, the results could be called mind boggling. That's how Michael Curti describes them. Curti is the president of Crest Foam Industries Inc., which manufactures reticulated polyurethane foams, as well as other specialty foams, used in such products as blood oxygenators for open heart surgery and new generation batteries for medical implants.

"These efforts help save and extend lives, eliminate or reduce pain, and benefit patients and healthcare providers in many ways," says Curti. "Advances in medical product technology have been mind boggling over the past few decades, perhaps culminating - at least today - in one of the most profound and exotic medical products to be employed on a practical basis - the implantable, self-contained, battery-powered artificial heart."

New Uses For Existing Foams

Medical breakthroughs are often the result of new materials entering the market. But they can also come from new uses for existing materials. One such material that is finding widespread use in the healthcare industry is reticulated polyurethane foam.

"Reticulated polyurethane foam is a unique and versatile material that can be fabricated, or combined with other materials, into almost any configuration," explains Curti. "Using conventional processing and production techniques, it is manufactured in large pieces called buns about the size of three or four mattresses on top of each other. Its properties and characteristics can be changed radically to broaden its scope of application possibilities."

When polyurethane foam is made, a thin membrane of polyurethane material encapsulates the foam cells, preventing the passage of gases or liquids through the foam. Special thermal techniques bring about a proprietary reticulation process that reconfigures it by removing the membrane, resulting in a completely open pore reticulated foam with a skeletal structure that allows fluids to pass through easily.

"The unique characteristics of reticulated polyurethane foam offer many special advantages particularly for filtration, absorption, wicking, wiping, and padding applications associated with medical devices and equipment," says Curti. "Applications for these materials range from the prosaic to the profound, and many new products for the healthcare market are now being produced."

From Heart-Lung Machines To Batteries

For example, reticulated foam can be coated with a surfactant that breaks down the bubbles caused in blood by oxygenation. "During open heart surgery, a heart-lung machine takes over the functions of these vital organs. The blood is circulated through the machine, which oxygenates and cleans it, and returns it to the body. During the oxygenation process, the blood is frothed, then channeled through the center of a reticulated foam `pocket,' and forced out through the foam cells," says Curti. "The surfactant coating on the foam cell structure coalesces the froth back into a liquid."

A new generation of batteries for medical devices is also relying on specialty reticulated foam. The application involves plating nickel onto foam and then annealing the part to vaporize the sacrificial foam substrate and making the nickel ductile. "This results in an anode or cathode plate which exhibits substantially increased surface area with which to hold a charge, adding reserve capacity and longevity to nickel batteries," says Curti.

Reticulated foams are known for their strength, consistent quality, and resistance to most chemicals. They typically contain void volumes of up to 98 percent and surface areas up to 2,000 square feet per cubic foot. Curti says they provide unprecedented application versatility, controlled permeability, design flexibility, and a pleasing aesthetic appearance.

More Medical Industry Examples

Following are some of the unique applications Curti listed as being met today by reticulated polyurethane foam and other specialty polyurethane foam materials.

* Reticulated foam filters with very fine pores are being used in medical nebulizers, ventilators, air compressors, and oxygen concentrators as a moisture evaporative medium as well as a filter. Some units use compressed reticulated foam felt, which further reduces the pore size for finer filtration.

* EKG pads generally contain a conductive gel under the electrode attachment. The gel allows the electrode to make electrical contact with the patient's skin. Fine pore reticulated foam is impregnated with the gel to keep it in place.

* Trays lined with reticulated polyurethane foam prevent surgical instruments from banging into each other. In addition, the hydrophilic material absorbs liquids from the instruments.

* Reticulated felted (compressed) foam is used in blood filters for analysis and research applications. The felted foam comes in varying degrees of density. Higher densities filter out smaller particles.

* Reticulated foam also prevents surgical instruments from contacting each other when in a steam autoclave for sterilization. Each instrument is placed in its own reticulated foam bag, which allows the steam to penetrate and do its job.

* Fine cell reticulated foam is used to fashion artificial legs. The foam is contoured to the shape of a leg and hollowed out. The prosthesis device is then inserted, and the foam is covered with a washable flesh colored film or stocking.

* Specialty polyurethane foam that is not reticulated is being used in athletic ankle wraps. It is very fine pore foam supplied in 0.75-mm thick rolls. Its elastic properties allow it to be stretched when wrapping an ankle or joint.

* Both reticulated and non-reticulated foams are used as hand scrub sponges by surgeons. The sponges can be impregnated with a steroid soap or used separately with soap.

* Slings and braces are lined with soft, fine pore reticulated foam to increase comfort. The foam has cushioning properties and breathability. It also can be washed repeatedly.

More information about reticulated polyurethane foams and specialty foams for medical applications is available by contacting Crest Foam Industries Inc., 100 Carol Place, Moonachie, NJ 07074, calling (201) 807-0809, writing in 60 on our reader service card, or replying online at
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Author:Arrigo, Lisa
Publication:Product Design & Development
Article Type:Brief Article
Geographic Code:1USA
Date:Nov 1, 2001
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