United kingdom Daily news: British scientists create artificial 'muscles' that can copy squid's ability to instantly change colour

Rabu, 02 Mei 2012

British scientists create artificial 'muscles' that can copy squid's ability to instantly change colour

British scientists create artificial 'muscles' that can copy squid's ability to instantly change colour

Military experts are very interest in fabric that could camouflage vehicles or troops at the flick of a switch
Tests copy two types of marine optical effects Â Â

By Daily Mail Reporter
UPDATED: 12:41 EST, 2 May 2012

Researchers from the University of Bristol have created artificial muscles that transform at the flick of a switch to mimic the instant camouflaging abilities of sea creatures.

Two different types of camouflaging mechanisms - one employed by the squid, and the other by the zebrafish - are shown in the demonstration.

Scientists say that the artificial 'skin' could be used in smart clothing or fabrics that would be able to change colour similar to camouflaging tricks witnessed in nature.

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Squid's ink: Scientists at the University of Bristol created artificial muscles that mimic the sea creature's ability to change colour

Quick-change: When affected by an electrical current, the muscles contract - giving the optical illusion that the colour has expanded

The study is published today in IOP Publishing's journal Bioinspiration and Biomimetics, and is accompanied by a video showing the camouflaging in action (see below).

Lead author of the study, Jonathan Rossiter, said: 'We have taken inspiration from nature's designs and exploited the same methods to turn our artificial muscles into striking visual effects.'

The artificial muscles are based on specialist cells called chromatophores that are found in amphibians, fish, reptiles and cephalopods.

Injecting liquid: In the case of the zebrafish, black fluid is 'pumped' to and from the skin surface, creating the colour change

The Bristol team achieved the zebrafish effect by swandwiching a silicone layer through glass plates and pumping the liquid both in and out

The colour changes in these organisms can be triggered by changes in mood, temperature, stress or something visible in the environment - and can be used for camouflage, communication or attracting a mate.

Two types of artificial chromatophores were created in the Bristol study: the first based on a mechanism adopted by a squid; and the second based on a rather different mechanism adopted by zebrafish.

A typical colour-changing cell in a squid has a central sac containing granules of pigment.

Look who's interested? Not surprisingly, military experts are very keen on technology that would allow troops or vehicles to blend into the background

The sac is surrounded by a series of muscles and, when the cell is ready to change colour, the brain sends a signal to the muscles and they contract.

The contracting muscles make the central sacs expand, generating the optical effect that makes the squid look like it is changing colour.

To achieve this, dielectric elastomers (DEs) - smart materials made of a polymer - were connected to an electric circuit and expanded when a voltage was applied.

Now you see it... The Japetella heathi, a type of squid that can change from transparent in brightly lit conditions, to opaque red when in the dark

Abraca-zebra: The colour-changing techniques employed by the zebrafish are different - but just as effective - to those used by the squid

In the second test, scientists mimicked the cells in the zebrafish, which contain a small reservoir of black pigmented fluid.

When activated, the fluid travels to the skin surface and spreads out.

To achieve this, a layer of silicone was sandwiched between two glass microscope slides.

Two pumps, made from flexible DEs, were positioned on both sides of the slide; one pumping opaque white spirit, the other a mixture of black ink and water.

Mr Rossiter said: '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.

'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.

The race to produce a workable colour-changing material is potentially lucrative to the winner.

The U.S. Office of Naval Research recently awarded $6 million to a team of U.S. scientists to conduct the basic research required to make the squid-like camouflage.