Scientists
have created
a soft,
stretchy
artificial
muscle that
can blend
with its
environment
at the flick
of a switch,
mimicking
the
camouflage
abilities of
squid and
zebrafish.
In a new
study,
detailed in
the current
issue of the
journal
Bioinspiration
and
Biomimetics,
the team
showed how
the
achievement
might be
used to
weave "smart
clothing"
that can
make their
wearers seem
to
disappear, a
la the
Predator
aliens.
"We have
taken
inspiration
from
nature's
designs and
exploited
the same
methods to
turn our
artificial
muscles into
striking
visual
effects,"
said leader
Jonathan
Rossiter of
the
University
of Bristol
in the UK.
The
artificial
muscles are
based on
color-changing
cells known
as
chromatophores,
which are
found in
amphibians,
fish,
reptiles,
and
cephalopods
such as
squids.
A typical
color-changing
cell in a
squid has a
central sac
containing
granules of
pigment. The
sac is
surrounded
by a series
of muscles
and when the
cell is
ready to
change
color, the
brain sends
a signal to
the muscles
and they
contract.
The
contracting
muscles make
the central
sacs expand,
generating
the optical
effect which
makes the
squid look
like it is
changing
color.
The
researchers
mimicked the
fast
expansion of
these
muscles
using
dielectric
elastomers
(DEs), a
so-called
smart
material
that expands
when zapped
with an
electric
current.
In contrast,
the cells in
the
zebrafish
contain a
small
reservoir of
black-pigmented
fluid that,
when
activated,
travels to
the skin
surface and
spreads out,
much like
spilled ink.
The natural
dark spots
on the
surface of
the
zebrafish
therefore
appear to
get bigger,
changing the
creature’s
overall
appearance.
The team
mimicked the
zebrafish
chromatophores
using two
glass
microscope
slides
sandwiching
a silicone
layer. Two
pumps, made
from
flexible
DEs, were
positioned
on both
sides of the
slide and
were
connected to
the central
system with
silicone
tubes; one
pumping
opaque white
spirit, the
other a
mixture of
black ink
and water.
"Our
artificial
chromatophores
are both
scalable and
adaptable
and can be
made into an
artificial
compliant
skin which
can stretch
and deform,
yet still
operate
effectively,"
Rossiter
said.
"This means
they can be
used in many
environments
where
conventional
'hard'
technologies
would be
dangerous,
for example
at the
physical
interface
with humans,
such as
smart
clothing."
Scientists have
created a soft,
stretchy
artificial
muscle that can
blend with its
environment at
the flick of a
switch,
mimicking the
camouflage
abilities of
squid and
zebrafish.
