Biomedical Engineering Reference
In-Depth Information
not through study of silkworms and spiders. As
with composites, the language of fiber spinning
developed a lexicon with which to discuss natu-
ral fiber spinning:
spinneret
,
extensional flow,
, and
liquid crystalline phases
were not terms used by
the early entomologists to describe their
observations.
Those comments notwithstanding, what is
currently happening is that biology is informing
engineering practice, in particular with respect
to sustainability, as well as novel structures.
Again, take the gecko, for example. The mystery
of the ability of the gecko to traverse smooth
surfaces at virtually any angle has been resolved
as a consequence of the nanoscaled hair-like
structures on its feet. Contemporaneously,
humans have learned how to make nanofibers,
so we now have gecko-like material
[18]
.
It is important to note that, without the
required maturity of fiber science, this develop-
ment would not have been possible and that the
development of nanofibers was not in response
to discovering gecko feet. It was instead the curi-
osity of physical scientists and engineers, striv-
ing to make ever-smaller fibers for their own
sake. As my good friend Julian Vincent would
say, however, “Physics deals with nature at such
an adaptable level that physicists think of their
own science as underpinning everything else …
but it is worth considering that there are so many
mechanisms waiting to be discovered in biology
that perhaps the study of living organisms is the
basic science, and physics is just a special case”
[19]
. I may choose to say physics has the source
of its power as a reductionist science, whereas
biology is proud to explore complexity.
textiles, and so I conclude this chapter with a dis-
cussion of biomimetics in the fiber area of textiles.
Readers interested in a more broad treatment
of textiles in biomimesis are commended to the
above reference. However, I will intersperse a few
points of textile interest here.
10.3.3.1 Apparel
One of the emerging new methods of coloration
of textile materials is through the interference
phenomenon that is the basis for coloration of
butterfly wings. In general, the butterfly wing
consists of two or more layers of small scales
resident on a membrane, which allow diffrac-
tion to occur. See the accompanying chapter on
structural colors.
Researchers in the Advanced Fiber-Based
Materials (AFBM) Center of Economic Excel-
lence at Clemson University demonstrated some
fibers that mimic the coloration process used by
the natural world, from butterfly wings to beetle
backs. Those materials display color by the
interference of white light reflected from several
layers within each fiber, resulting in a fiber that
changes color with viewing angle, without the
use of dyes
[21]
. This is a different approach to
some of the work done by commercial fiber
manufacturer Teijin, which produced a fiber
called Morphotex
®
that mimics the microstruc-
ture of
Morpho
butterfly wings to produce struc-
tural color. The fiber, made of either polyester or
nylon, has more than 60 laminated layers of
nanometer dimension
[18]
.
In addition to the fashion aspect, protective
equipment is an important area of textiles and
apparel. One such application is reviewed in
Section
10.3.3.4
in the discussion of byssus thread
sheathing. It is relevant to note here that recent
applications of shear thickening fluids, although
perhaps not directly biomimetic, have gained
some traction. In this instance, incorporation of
a viscous material with a viscosity that increases
with shear rate has been shown to improve bal-
listic protection. An armor composite material
10.3.3 The Marriage: Bioinspiration with
Fibrous (Textile) Materials Engineering
I have reviewed a broad set of the work on
biomimetics in textiles
per se
in a recent topic chap-
ter
[20]
. My current area of interest encompasses
the study of biomimetic fibers more than general
