MADE FROM NATURE

puppypompAI and Robotics

Nov 14, 2013 (3 years and 9 months ago)

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MADE FROM NATURE
FEATURES
The field of biomimetics
- man-made products in-
spired by nature - is now
starting to come into its
own. Here are some of the
new products that have
been inspired by nature.
Some are practical, some
are bizarre. They range
from glass substitutes
based on the honeycomb
to a fashion fabric that
looks and feels like human
skin.
ALL IMAGES CREDIT: PASCAL GOETGHELUCK/SCIENCE PHOTO LIBRARY
T
he shark and the
butterfly, even the
lowly pine cone, are
inspiring scientists and
engineers to create new
materials ranging from
paint that changes colour
to clothing that adapts to
changes in temperature.
This field of science is
known as ‘biomimetics’.
The concept isn’t new –
Velcro, which is based on
the way tiny hooks found
on burrs stick to clothing
and animal fur – was pat-
ented back in the 1950s.
But biomimetics is now
starting to come into its
own. Here are some of the
new products that have
been inspired by nature.
Some are practical, some
are bizarre. They range
from glass substitutes
based on the honeycomb
to a fashion fabric that
looks and feels like human
skin.
The leaf of the lotus plant
has an amazing ability
to repel water. Droplets
glide off the surface with
ease. It took the power of
the electron microscope
to reveal that the effect –
known as ‘hydrophobia’
– is caused by tiny bumps
that cover the leaf’s
surface. These bumps
increase the contact angle
of the water droplet to
the surface – the droplet
is forced to form a sphere
which then rolls off the
surface.
This ‘lotus leaf effect’ has
now been incorporated
into fabric. It too has a
surface covered in millions
of tiny bumps, and water
simply runs off it.
The lotus leaf effect has an
additional benefit: surface
dirt also finds it difficult
to cling to the bumpy
surface, so can be simply
washed off by rainwater.
So new paints have been
developed that are both
water-repellent and self-
cleaning.
Natural microscopic
structures exhibit another
fascinating property – they
can be incredibly sticky.
Geckos can walk upside-
down, apparently defy-
ing gravity. After years of
study, researchers found
that the ability to stick to
walls and ceilings was due
to a network of tiny hairs
on the creatures’ feet.
These structures create a
tremendous adhesive ef-
fect, which has now been
used to create … Gecko
Tape. Yes, it’s artificial
Gecko foot material that’s
made up of nearly 30,000
microscopic gripping
elements every square
centimetre. Gecko Tape
is elastic, sticks to any
surface, even if it’s wet or
slippery, and doesn’t leave
any marks.
Shark skin is another
natural material that has
been intensively studied.
The tiny, diamond-shaped
microstructures – known as
‘denticles’ – that give shark
skin its rough surface also
allow the creatures to speed
through the water, hence
swimsuits made from artificial
shark skin. But what wasn’t
known until recently is that
shark skin is also a natural
antibiotic. Its rough, denticle-
studded surface deters bacte-
ria from establishing colonies
and spreading. This effect had
been reproduced in an artifi-
cial film patterned with mil-
lions of artificial denticles. As
well as coating medical instru-
ments, the developers plan
to use it to cover toilet doors
and handles, thus preventing
the transmission of bacteria by
touch.
Perhaps the most efficient of
nature’s designs is the honey-
comb. Its array of thin-walled
hexagonal cells makes a
lightweight yet robust struc-
ture. The most recent artificial
honeycomb is made from
plastic and is used as a ‘filling’
for composite glass panels
that are tough but lightweight.
The plastic honeycombs are
designed so that sunlight is
‘gathered’ along the tubes, so
they act as natural light inten-
sifiers. And they also minimise
heat loss, just like a beehive.
Another area of practical
biomimetics, where new
materials inspired by nature
are coming into everyday
life, is iridescence, or colours
that change depending on
the angle of the viewer. But-
terfly wings, peacock tails and
mother of pearl are all exam-
ples of natural iridescence.
The electron microscope
reveals that iridescence is
caused by tiny microstructures
that reflect light in different
ways, rather than the con-
ventional pigments in paint.
These microstructures have
now been reproduced to give
paints, plastics and fabrics the
ability to change colour when
viewed from different angles.
The uses are legion: from cars
to clothing, a new world of
constantly changing colours.
Similarly, dichroic glass, an
artificial version of iridescent
mother of pearl, is now being
used in windows, skylights –
even eyeglasses and fabrics.
Even the humble pine cone
has given researchers a new
material. It’s called C_Change,
and it’s a fabric that is sen-
sitive to climate – just like
the female pine cone. When
temperatures are warm and
humidity low, the female
pine cone senses that condi-
tions are optimal and opens
her scales for seed dispersal.
Conversely, when it’s cold and
humid, she closes her scales.
C_Change is a material that
operates in a similar fashion. It
incorporates a polymer whose
structure closes when it’s cold
or when the wearer is inactive,
thus trapping heat. But when
the wearer is sweating and the
body temperature is high – for
example, while running – the
structure opens to release
heat and moisture. It’s being
used to make clothing that ac-
tually responds to the wearer
and the weather conditions
around them.
It’s like something from a sci-
ence fiction movie: a self-heal-
ing resin that can be moulded
into any shape. If cut, the two
pieces will magically self-
heal when pressed together,
without glue or heating. And
if you stretch it, it will revert
back to its original shape,
even if reconnected hours
later. This memory material
is made from polymer chains
found in vegetable oil. These
have ‘reversible’ links between
their molecules: when pushed
together, the polymer chains
reconnect naturally. In many
respects it ‘heals’ itself much
like living tissue.
Probably the most bizarre of
the new materials inspired
by nature is … skin. Called
‘Skinbag’, it’s a latex material
designed to mimic the look
and feel of human skin. The
fashion industry is already
producing handbags from
the material. Sooner or later,
someone’s going to make a
whole body suit from it, thus
walking around in … a real
second skin.
ENDS 890 WDS © SCIENCE
PHOTO LIBRARY 2012
ALL IMAGES CREDIT: PASCAL GOETGHELUCK/SCIENCE PHOTO LIBRARY