Putnam, CT (April, 2004) - Today, value and size are intertwined. Like never before, our society demands higher performance AND smaller packaging. This is the central premise driving the industry of minimally invasive surgery.
Catheter based devices are now available to reach inside the smallest of areas of the body and treat diseases with greater safety and less trauma to patients. These devices utilize the latest technologies to construct engineering marvels of design, function, manufacturability and reliability.
Since catheter devices are based on tubes, design enhancements are finite. The challenge of creating the next generation products will rest predominantly on advanced materials to provide greater and more versatile performance in smaller sections.
Melt compounded nanocomposites, using thermoplastics and Montmorrilonite clay, show promise of helping engineers meet tomorrows medical design challenges. These materials offer a balance of properties not previously attained with other resin systems or materials. Material development, regulatory validation, and scale-up to commercialization are uniquely challenging steps for nanocomposites in the medical industry.
Nanocomposites based on thermoplastics and nano-clays have demonstrated unique properties of high stiffness, high strength, translucency, extrude ability in thin walls (down to 0.5 m) excellent surface smoothness and high elongation. The most common thermoplastics used are Nylon 12, Poly-ether-block amide (Pebax), and polyurethane with nano-clay loadings varying from less than 1% to more than 25%. Properties are enhanced by adding exfoliating agents, stabilizers and processing aids. Nanocomposites have been formulated to provide radiopacity, lubricity, UV stabilization and color.
Materials for medical devices have special requirements since the FDA lists catheters as class 2 or class 3 devices. Certain validations are required prior to using any new materials. Substitution of nanocomposites for existing materials is impractical due to the time and money required for validation. As such, the focus for these materials is on new application developments.
Material validations may also include biocompatibility, sterilization capability, property characterization and process capability studies. Nanocomposites have already been proven suitable for short-term body fluid contact use. Further testing is still required to determine the suitability of nanocomposites in permanent implants.
Scale-up of these materials to commercialization has perhaps been most challenging. Several hurdles had to be overcome since the materials were out of scale with existing manufacturing and testing methods. New methods of handling the powders in a safe manner had to be developed. Feeding technology had to be optimized for required accuracy of loading levels. Small changes in filler loading had a significant effect on properties. The compounding process had to be defined and made robust utilizing DOE methods. Quality control tests had to be established and modified to achieve the required gauge R&R. The most important control variables were found to be: loading level, exfoliation, viscosity and flexural modulus.
The scale-up from development to production required a significant amount of additional engineering initially unforeseen. The appropriate selection of co-development partners was found to be the key driver of a successful nanocomposite implementation. Ideal partners visualize the benefits of nanocomposites, have senior management commitment, are open with information and can supplement development with financial and/or engineering resources.
According to Foster president Larry Acquarulo, "The primary focus during the next few years will be to develop several applications and scale-up the currently available compounds for production. A secondary emphasis will also be to further the development of cross linkable nanocomposites, POSS and other nano sized fillers."
Nanocomposites are available now and with a little extra engineering support and determination, advanced medical devices can benefit from the promise of this new technology.
Foster is a global market leader in design, development and delivery of specialty thermoplastic and fluoropolymer materials. The company provides material solutions to start-up through Fortune 500 companies world-wide from two facilities and three business units, including BioMedical Polymers, Applied Polymer Development, and Supply Chain Management. For more information, please call (860)729-0251.
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Contact:Dan Lazas
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