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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.
UNCLASSIFIED/,,s:,111: OS:PIII.. L U81! eruc; Biodegradable polymers have been used with computer-based rapid prototyping machines to form porous shapes where tissue cells can ingrow. The result after many weeks of submersion in tissue culture is that the polymer slowly degrades, leaving the cultured tissue in the shape of the predefined scaffold. Although this approach cannot grow complex organs, like a heart or kidney, that have many different tissues, it can be used to create simple structures of cell products-for example, of cartilage excreted by fibroblast cells. These structures do not create their own networks of blood vessels, a problem whose solution lies in the future. Figure 20 shows CSLA (Crosslinkable Star Lactide-co-Glycolide), a biodegradable polymer deposited into a honeycomb structure by a process not unlike ink-jet printing. The ink-jet pen is supplied with a hot liquid form of the CSLA polymer, which then hardens when it cools and is exposed to the air. Using a computer to rewrite successive layers on top of one another, a three-dimensional structure is built. Figure 20. Biodegradable Material CSLG Deposited in a Honeycomb Structure to Allow Infiltration by Living Cells While in a Submerged Cell Culture CARDIOVASCULAR BIOMATERIALS Biomaterials are often made into medical devices rather than being sold in raw form. Among the largest and most demanding of all biomaterial applications are devices that come into direct contact with blood. In general 1 various derivatives of Teflon and silicone are the most widely used for blood contact, while metals and ceramics are more often used in tissues. Cardiovascular (heart and blood vessel) applications are one of the most important categories of implant biomaterials. Biomaterials for cardiovascular applications are usually prepared using polymers, because polymers are available in a wide variety of compositions with adequate physical and mechanical properties and can easily be manufactured into products with the desired shape. In addition, some metals and ceramics are used in the blood stream. Figure 21 lists some of the common cardiovascular devices and how long they are in contact with blood. 15 UNCLASSIFIED/; (50B AFEICJOP 1!SE ON! ¥
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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.