The Institute of Physics (IOP) journal, Bioinspiration and BIomimetics, has published an open access article on camouflage inspired by zebrafish and squid. From the IOP’s May 2, 2012 news release
Researchers from the University of Bristol have created artificial muscles that can be transformed at the flick of a switch to mimic the remarkable camouflaging abilities of organisms such as squid and zebrafish.
They demonstrate two individual transforming mechanisms that they believe could be used in ‘smart clothing’ to trigger camouflaging tricks similar to those seen in nature.
The soft, stretchy, artificial muscles are based on specialist cells called chromatophores that are found in amphibians, fish, reptiles and cephalopods, and contain pigments of colours that are responsible for the animals’ remarkable colour-changing effects.
Here’s the video mentioned in the IOP’s May 2, 2012 news release,
The lead author Jonathan Rossiter provides a description of the work (which may help you better understand what you’re seeing on the video), from the May 2, 2012 news item,
Two types of artificial chromatophores were created in the 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. 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 which makes the squid look like it is changing colour.
The fast expansion of these muscles was mimicked using dielectric elastomers (DEs) – smart materials, usually made of a polymer, which are connected to an electric circuit and expand when a voltage is applied. They return to their original shape when they are short circuited.
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 the spilling of black ink. The natural dark spots on the surface of the zebrafish therefore appear to get bigger and the desired optical effect is achieved. The changes are usually driven by hormones.
The zebrafish cells were mimicked 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. 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,” continued Rossiter.
I wonder what these smart clothes/smart skin would feel like against your personal skin given that we are talking about ‘artificial muscles’. For example, how much movement would your clothing/smart skin have independent of you?
By independent, I mean that everything occurs externally. While we’re not ordinarily conscious of all our physical responses they are stimulated internally and part of a whole body response (even though we may notice only localized responses, e.g., a rash). In the research, there’s an external stimulus and an external response via smart clothes/smart skin.
This is just speculation as I imagine we’re several years away from any field testing of these smart clothes/smart skin, assuming that scientists are able to address all the technical hurdles between a laboratory breakthrough and developing applications.
Thanks to Nanowerk where I first came across this information (May 2, 2012 news item).