AAWSAP DIRD, Biomaterials, January 2010

This Defense Intelligence Reference Document, dated 7 January 2010, was prepared by the Defense Intelligence Agency's Defense Warning Office. It is one of a series of advanced technology reports produced in FY 2009 under the Advanced Aerospace Weapon System Applications program. The report reviews biomaterials used in medicine, including silicones, Teflon, biodegradable polymers, hydrogels, titanium, ceramics and tissue constructs, and applications such as stents, joints, contact lenses, drug delivery and dialysis. It concludes that most innovation lies in new ways to apply existing materials.

From the source:Release of 2026-09-18 Incident: 1/7/10, Las Vegas, Nevada. Released with redactions. This document is a Defense Intelligence Reference Document (DIRD), a technical reference format used by the Defense Intelligence Agency (DIA) to capture baseline knowledge on a specific topic for later analytic use. DIRDs are best understood as reference and synthesis products rather than as original research. It is one of 38 DIRDs produced under the Advanced Aerospace Weapon System Applications Program (AAWSAP) between 2009 and 2011. Because AAWSAP’s scope permitted a broad range of supporting topics, not every DIRD in the series directly concerns aerospace systems or future threat assessment. The following summary reflects the DIRD’s scope and framing at the time of writing and should not be read as implying current validation of the concepts discussed. This DIRD is a broad survey of biomaterials, including metals, polymers, ceramics, glasses, and composites designed to interact with living tissue, and argues that their value depends mainly on biocompatibility, reliability, and careful matching of material properties to specific medical uses. The report reviews major application areas including biosensors, implants, cardiovascular devices, contact lenses, drug delivery systems, tissue constructs, titanium devices, and dialysis membranes, emphasizing that no single biomaterial works best in every setting. Its overall conclusion is that biomaterials are already foundational to a large medical-device industry and save or improve millions of lives, but that progress tends to be slow because safety testing is stringent; as a result, most advances come from improved ways of applying established materials such as silicone, Teflon, biodegradable polymers, ceramics, and titanium in new devices and clinical settings rather than from radically new substances.

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Heart valves are another application
of biomaterials in which the materials
are in direct contact with blood. They
are typically constructed using a form
of stainless steel and woven Teflon (or
Dacron) as a suture ring to anchor the
device. Figure 24 shows one of these
devices.
STENT BIOMATERIALS
A stent is a metal mesh tube that
looks something like a Chinese finger
puzzle and is used to prop open a
clogged artery. These are delivered to
the heart in a catheter on the end of a
wire usually inserted into an artery in
the groin.
The stent is collapsed to a small
diameter and placed over a balloon
catheter. It is then surgically moved into the area of the blockage. When the balloon is
inflated, the stent expands, locks into place, and forms a scaffold that holds the artery
open. Figure 25 shows an artist's conception of this process.
The stent stays in the artery
permanently, holds it open, improves
blood flow to the heart muscle, and
relieves symptoms (usually chest
pain). With in a few weeks after the
stent was placed, the inside lining of
the artery (the endothelium) grows
over the metal surface of the stent.
Stents are often made from a form of
stainless steel that is ductile enough
to be expanded by a balloon and then
resist closure forces of the vessel wall
after the balloon is removed.
The insertion and use of the balloon to
expand the stent involves some Figure 25. Illustration of Stent Placement. The stent is
hazards that can be overcome if the used to expand the luminal opening of a clogged blood
stent is made from a self-expanding vessel.
metal called Nitinol™. With a nitinol
stent, the stent is placed into the body collapsed while it is held cold by a flow of
refrigerated saline through the catheter. When allowed to heat up to body temperature
by shutting off the cold water to the catheter, the stent expands and more reproducibly
applies a calibrated amount of pressure to the blood vessel walls .
Figure 24. Stainless Steel and Teflon Bjork Shiley
Heart Valve
Dilated balloon
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