Small - Nanotechnology—with its ability to write pages
of information on the point of a pin—has NASA scientists
thinking small. Really small. (5/10/01)
Elsewhere on the web
looks to nanotechnology, robotics - gyre.com
future for soldiers - BBC
Fibers Reflect All Comers - Chemical & Engineering News
Today’s soldiers are armed with so many high-tech gadgets that they’re
advertised as “an army of one.”
Now, as this ScienCentral news video reports, it looks like one of those high-tech
devices may be the uniform itself.
On the battlefield or on patrol, soldiers risk being separated from their
own troops. They need a way to distinguish their side from the enemy. So scientists
at the Massachusetts Institute of Technology’s (MIT) Institute
for Soldier Nanotechnologies (in partnership with the U.S. Army) set out
to create a fabric that carried an optical bar code, visible only to someone
wearing special goggles.
assistant professor of materials science at MIT, specializes in inventing
new materials. In 1998, he and his colleagues created what he calls a "perfect
mirror," capable of reflecting any and all light that strikes it,
from any direction. This mirror doesn't look like a mirror at all. Unlike
conventional mirrors, it is a flat metallic gray. Seen through infrared goggles,
however, it is extraordinarily reflective, giving off a portion of the light
spectrum that is invisible to our unaided eyes. Fink wanted to create a fiber
made of these powerful mirrors, but in order to do so the mirrors would have
to be reduced in size to the width of a human hair. This is the realm of nanotechnology.
Nanotechnologists are scientists who manipulate structures at microscopic levels,
in order to obtain new
and extraordinary properties. Some nanotechnologists start at nanoscale,
or the atomic level. (A nanometer is hundreds of times less than the width
of a human hair.) Others work to reduce large materials to nanoscale. To fashion
his perfect mirror into mirror fiber, Fink needed a special process that would
shrink the layers enormously, without destroying their arrangement and retain
their high reflectivity.
The mirrors are made of glass and plastic. Both have very different optical
properties: light travels more quickly through the plastic. But these two
materials react in the same way to heat—they flow together when heated
to a particular temperature.
One of Fink’s students, Shandon Hart, and his co-workers at MIT's Department
of Materials Science, constructed a cylinder made of thick, alternating
layers of the two materials. They fed the cylinder into a tall, narrow lab
furnace, called a draw tower. In the heat, the cylinder thins out drastically
and stretches into a long, slim fiber. Inside it, the layers remain intact
while shrinking in thickness. Along the way they become strongly
reflective. The entire process is controlled by a laser-thickness measuring
device, which allows the user to set the final layer thickness at will.
Next, Fink and his students will transform the mirror fiber into thread that
can be woven into fabric. The U.S. Army is interested in weaving Fink's thread
into uniforms to produce a special colored signature. Visible only to our
soldiers, it would help them recognize each other, even
through smoke, fog, or darkness.