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This Defense Intelligence Agency reference document, dated 7 January 2010 and prepared under the Acquisition Threat Support series, surveys biomaterials used in medicine. It covers biocompatibility, biosensor membranes, silicones, Teflon, biodegradable polymers, hydrogels, titanium, bioceramics, tissue constructs, cardiovascular stents, contact lenses, drug delivery and dialysis. It concludes that biomaterial performance underlies many medical devices, that the industry is slow to adopt new materials because of testing costs, and that innovation mainly involves new applications of established materials.
UNCLASSIFIEDJ;fFGII GFFl&IIL W&I ONla¥ TEFLON Biomedical materials must be inert to the complex chemistry of biological fluids so they neither suffer nor instigate change in tissue. TeflonTM admirably fulfills these requirements. Teflon is a trade name for polytetrafluoroethylene (PTFE}, a fluorocarbon-based polymer. It is made by free radical polymerization of tetrafluoroethylene and has a carbon backbone chain in which each carbon has two fluorine atoms attached to it. This polymer is hydrophobic (water hating), biologically inert, and nonbiodegradable and also has low friction characteristics and excellent "slipperiness." The chemical inertness (stability) of PTFE is related to the strength of the fluorine-carbon bond that makes it resistant to adhesion. Figure 8 shows the structure of this material. It is a long chain of repeating chemical units, as shown in the right of the figure. F F I I -fc-c~ F ~ Figui:e 8. Teflon Structure Goretex® is a medical form of Teflon (PTFE) that, when stretched and extruded, entraps air cells in its microstructure much like foam does and, thus, is relatively soft and repellant to most liquids: This material is known as e-PTFE (expanded PTFE). PTFE can be fabricated rn many forms, includrng pastes, tubes, strands, and sheets, whlle ePTFE can be ~oven into a porous, fabric-like mesh. When implanted in the body, this strong mesh allows tissue to grow into its pores, making it ideal for medical devices such as vascular grafts. 6 UNCLASSIFIED/1f P811 8FFICle ■ 1155 ON! Y
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Report, from the dia collection. The PDF is mirrored here; the original link is above. 32 pages are in the text index: search them above, or from the library's search.