Tag Archives: camouflage

Are living bacteria providing camouflage for crustaceans?

When you have no place to hide, you can develop some unique methods to avoid detection according to an Oct. 27, 2016 news item on ScienceDaily,

Crustaceans that thrive in the vastness of the open ocean have no place to hide from their predators. Consequently, many creatures that live at depths where sunlight fades to darkness have developed transparent bodies to be less visible when spotted against the twilight by upward-looking predators. But they also face predators with bioluminescent searchlights that should cause the clear animals to flash brightly, just like shining a flashlight across a window pane.

Well, it turns out the midwater crustaceans have camouflage for that too.

An Oct. 27, 2016 Duke University news release on EurekAlert, which originated the news item, expands on the theme,

A new study from Duke University and the Smithsonian Institution has found that these midwater hyperiid amphipods are covered with anti-reflective coatings on their legs and bodies that can dampen the reflection of light by 250-fold in some cases and prevent it from bouncing back to a hungry lantern fish’s eye.

Weirder still, these coatings appear to be made of living bacteria.

When viewed under an electron microscope, the optical coating appears as a sheet of fairly uniform beads, smaller than the wavelength of light. “This coating of little spheres reduces reflections the same way putting a shag carpet on the walls of a recording studio would soften echoes,” said study leader Laura Bagge, a Ph.D. candidate at Duke working with biologist Sönke Johnsen.

The spheres range from 50 to 300 nanometers in diameter on different species of amphipod, but a sphere of 110 nm would be optimal, resulting in up to a 250-fold reduction in reflectance, Bagge calculated. “But every size of these bumps helps.”

Adding to the impression that the spheres might be bacteria, they are sometimes connected with a net of filaments like a biofilm. Each of the seven amphipod species Bagge looked at appears to have its own species of symbiotic optical bacteria. But that’s not a sure thing yet.

“They have all the features of bacteria, but to be 100 percent sure, we’re going to have to perform an in-depth sequencing project,” Bagge said. That project is already underway.

If the spheres are bacteria, they’re very small ones. But it’s not hard to imagine the natural selection — having your host spotted and eaten — that would drive the microbes to an optimal size, said research zoologist Karen Osborn of the Smithsonian National Museum of Natural History, who provided some of the species for this study.

If the optical coating is alive, the researchers will have to figure out how this symbiotic relationship got started in the first place.

Crustaceans molt to grow, shedding the old shell and perhaps its attendant anti-reflective bacteria. But Osborn thinks it would be pretty easy to re-seed the animal’s new shell. “In that whole process, they’re touching the old carapace.” There’s also a species of hyperiid, Phronima, that raises its young in a little floating nest hollowed out of the body of a salp. In that case, the kids could adopt mom’s anti-reflective bacteria pretty easily, Osborn said.

Another amphipod species, Cystisoma, also extrudes brush-like structures on the exoskeleton of its legs which are just the right size and shape to serve the same purpose as the antireflective spheres. At up to six inches in length, Cystisoma has a serious need for stealth.

“They’re remarkably transparent,” Osborn said. “Mostly you see them because you don’t see them. When you pull up a trawl bucket packed full of plankton, you see an empty spot – why is nothing there? You reach in and pull out a Cystisoma. It’s a firm cellophane bag, essentially.”

“We care about this for the basic biology,” Bagge said. But the discovery of living anti-reflective coatings may have technological applications as well. Reflection-reducing “nipple arrays” are being used in the design of glass windows and have also been found in the eyes of moths, apparently to help them see better at night.

Here’s a link to and a citation for the paper,

Nanostructures and Monolayers of Spheres Reduce Surface Reflections in Hyperiid Amphipods by Laura E. Bagge, Karen J. Osborn, Sönke Johnsen. Current Biology DOI: http://dx.doi.org/10.1016/j.cub.2016.09.033 Publication stage: In Press Corrected Proof

This paper is behind a paywall.

Oscar of Between: a commentary

Whether it’s a piece of visual art, a musical performance, a dance performance, a theatrical performance, or a work of literature, material which comes from the soul deserves a degree of vulnerability and a willingness to confront the self from its reviewer.

Written by Betsy Warland, ‘Oscar of Between: A Memoir of Identity and Ideas’ seems as much a geography as it is a memoir.  Given that ‘in’ prefaces the word ‘between’ almost always the title ‘Oscar of Between’ draws attention to itself . The ‘of’  calls to mind naming conventions where geography (or place) play a role, Catherine of Russia, Henri IV of France, the Earl of Essex, and so on. Like Oscar, Catherine and her ilk also have a given name. In any event, the title seems to be notice that the author is staking a claim on her territory, a place called ‘between’. The allusion to geography doesn’t stop there, throughout the memoir there are  diary-like entries which include dates and places. The contrast between concrete locations such as Vancouver, Iowa, Berlin, etc. and the imaginary location ‘between’ is dislocating and there is more to come.

Oscar/Betsy maps a number of themes including but not limited to androgyny, camouflage, art and lies, war and violence, and recognition for one’s work.

Oscar brings to the forefront a disconcerting and delicately handled discussion about sexual identity where one is neither/nor. She is a lesbian who’s had a son but is frequently identified by others as a man (in part due to flat chest from a double mastectomy). What does it mean to be androgynous or perceived to be androgynous? There is no answer as this memoir is an exercise in geography, that is, exploration and naming followed by more exploration.

The war and camouflage themes make their appearances early on. Of course, war is part of the author’s name, Warland, and, as it turns out, a visit to one of the Imperial War Museum’s 2007 exhibitions in London inspires Oscar’s interest in camouflage and one of themes for this memoir.

While zoological and botanical camouflage occur in nature, Oscar’s focus is on military camouflage some of which has been designed by artists bringing thoughts of art and lies. (Before moving further with that, it bears noting camouflage, a form of deception, is about ‘seeing without being seen’, a description of sorts for the artistic process.)

Getting back to lies, early on in the book there’s a quote from the most famous literary Oscar in the English language, Oscar Wilde,

The final revelation is that lying, the telling of beautiful untrue things, is the proper aim of art. (p. 21)

A reference to her own then unfinished essay, “Narrative and the lie,” is made on the previous page and when taken in conjunction with the quote appearing shortly after the question arises is anything in this memoir true? What is the lie or where are the lies?

It’s possible there are some factual lies in this memoir but the little I do know about the author that was mentioned in this work was factually correct.

There is other ways for a writer to lie. In one’s pursuit of the ‘truth’ there are many inchoate revelations that can only be inadequately put into words and sentences. In short, by trying to pin down the inchoate with words, you’re left with a partial truth at best.

Further, efforts to get the complete truth on the page can render it incomprehensible. (As a technical writer I once wrote up a process precisely and in complete detail then asked someone else on the team to read it. After, the other technical writer looked me and said something like this, “I didn’t understand anything.” I went back and edited out most of the detail so the description was no longer as accurate or complete but hopefully more helpful to the users.) There are lies of omission and commission and sometimes writers lie both ways.

In keeping with the military camouflage motif, Oscar’s foray into war and violence makes unheralded and unexpected appearances throughout much of the narrative which ranges from spare poetic lines and imagery to a denser style of text seeming to reflect an interplay between silence and communication and between feelings and ideas.

Throughout the work there is an emphasis on observation and questioning over explanations and experiential descriptions. Certainly, that’s how Oscar treats the issue of recognition. There are no recriminations or rants about why an artist with Warland’s body of work is not included in certain conferences and, until relatively recently, has never been awarded a Canada Council grant.

Ironic that a writer who wishes to see rather than be seen wants recognition. (The desire to see without being seen is true of all writers  who must always hold some part of themselves in reserve so they may observe the action for future reference.)

There are contradictions and ironies throughout ‘Oscar of Between’ some of which results in a kind of wry humour. There is also a sense of a distanced compassion perhaps most strongly conveyed by the pauses or silences (the white space between the lines) in the sections with sparse text. It’s those things which don’t fit so well, the descriptions of societal violence which give this memoir it’s dynamism.

For a memoir concerned with lies, camouflage, war and violence, and more, it is strangely contemplative. I do recommend reading it but be prepared to go down some unexpected byways and for a haunting experience which may end when you have finished reading.

Other reviews and commentaries

March 29, 2016 review by Julie R. Enszer for lambdaliterary.org

April 18, 2016 review by Julie R. Enzer for Gay Sonoma.com (not identical to her March 2016 review for Lambda)

April 20, 2016 review by Maree for Autostraddle.com

More Oscar from Betsy

Betsy Warland is hosting an Oscar’s Salon on her website where she invites other artists and writers to ruminate on ‘Oscar of Between’ (keep scrolling down to get to individual entries).

Full disclosure: I received a review copy of the memoir and was taken out to lunch.

Omnidirectional fish camouflage and polarizing light

I find this camouflage technique quite interesting due to some nice writing, from a Nov. 19, 2015 Florida Atlantic University (FAU) news release on EurekAlert,

The vast open ocean presents an especially challenging environment for its inhabitants since there is nowhere for them to hide. Yet, nature has found a remarkable way for fish to hide from their predators using camouflage techniques. In a study published in the current issue of Science, researchers from Harbor Branch Oceanographic Institute at Florida Atlantic University and collaborators show that fish scales have evolved to not only reflect light, but to also scramble polarization. They identified the tissue structure that fish evolved to do this, which could be an analog to develop new materials to help hide objects in the water.

HBOI researchers and colleagues collected more than 1,500 video-polarimetry measurements from live fish from distinct habitats under a variety of viewing conditions, and have revealed for the first time that fish have an ‘omnidirectional’ solution they use to camouflage themselves, demonstrating a new form of camouflage in nature — light polarization matching.

“We’ve known that open water fish have silvery scales for skin that reflect light from above so the reflected intensity is comparable to the background intensity when looking up, obliquely at the fish, as a predator would,” said Michael Twardowski, Ph.D., research professor at FAU’s HBOI and co-author of the study who collaborated with co-author James M. Sullivan, Ph.D., also a research professor at FAU’s HBOI. “This is one form of camouflage in the ocean.”

Typical light coloring on the ventral side (belly) and dark coloring on the dorsal (top) side of the fish also can help match intensity by differential absorption of light, in addition to reflection matching.

Light-scattering processes in the open ocean create spatially heterogeneous backgrounds. Polarization (the directional vibration of light waves) generates changes in the light environment that vary with the Sun’s position in the sky.

Polarization is a fundamental property of light, like color, but human eyes do not have the ability to sense it. Light travels in waves, and for natural sunlight, the direction of these waves is random around a central viewing axis. But when light reflects off a surface, waves parallel to that surface are dominant in the reflected beam. Many visual systems for fish have the ability to discriminate polarization, like built-in polarized sunglasses.

“Polarized sunglasses help you see better by blocking horizontal waves to reduce bright reflections,” said Twardowski. “The same principle helps fish discriminate objects better in water.”

Twardowski believes that even though light reflecting off silvery scales does a good job matching intensity of the background, if the scales acted as simple mirrors they would impart a polarization signature to the reflected light very different from the more random polarization of the background light field.

“This signature would be easily apparent to a predator with ability to discriminate polarization, resulting in poor camouflage,” he said. “Fish have evolved a solution to this potential vulnerability.”

To empirically determine whether open-ocean fish have evolved a cryptic reflectance strategy for their heterogeneous polarized environments, the researchers measured the contrasts of live open-ocean and coastal fish against the pelagic background in the Florida Keys and Curaçao. They used a single 360 degree camera around the horizontal plane of the targets and used both light microscopy and full-body video-polarimetry.

The American Association for the Advancement of Science (AAAS), publisher of Science magazine where the researchers’ study can be found issued a Nov. 19, 2015 news release on EurekAlert further describing the work,

… The study’s insights could pave the way to improvements in materials like polarization-sensitive satellites. Underwater, light vibrates in way that “polarizes” it. While humans cannot detect this vibrational state of light without technology, it is becoming increasingly evident that many species of fish can; lab-based studies hint that some fish have even adapted ways to use polarization to their advantage, including developing platelets within their skin that reflect and manipulate polarized light so the fish are camouflaged. To gain more insights into this form of camouflage, Parrish Brady and colleagues measured the polarization abilities of live fish as they swam in the open ocean. Using a specialized underwater camera (…), the researchers took numerous polarization measurements of several open water and coastal species of fish throughout the day as the sun changed position in the sky, causing subsequent changes in the polarization of light underwater. They found that open water fish from the Carangidae fish family, such as lookdowns and bigeye scad, exhibited significantly lower polarization contrast with their backgrounds (making them harder to spot) than carangid species that normally inhabit reefs. Furthermore, the researchers found that this reflective camouflage was optimal at angles from which predators most often spot fish, such as from directly below the fish and at angles perpendicular to their length. By looking at the platelets of open water fish under the microscope, the team found that the platelets align well on vertical axes, allowing fish to reflect the predictable downward direction of light in the open ocean. Yet the platelets are angled in way that diffuses light along the horizontal axis, the researchers say. They suggest that these different axes work together to reflect a wide range of depolarized light, offering better camouflage abilities to their hosts.

The AAAS has made available a video combining recordings from the researchers and animation to illustrate the research,

Be sure you can hear the audio as this won’t make much sense otherwise.

Here’s a link to and a citation for the paper,

Open-ocean fish reveal an omnidirectional solution to camouflage in polarized environments by Parrish C. Brady, Alexander A. Gilerson, George W. Kattawar, James M. Sullivan, Michael S. Twardowski, Heidi M. Dierssen, Meng Gao, Kort Travis, Robert Ian Etheredge, Alberto Tonizzo, Amir Ibrahim, Carlos Carrizo, Yalong Gu, Brandon J. Russell, Kathryn Mislinski, Shulei Zha1, Molly E. Cummings. Science 20 November 2015: Vol. 350 no. 6263 pp. 965-969 DOI: 10.1126/science.aad5284

This paper is behind a paywall.

India’s S. R. Vadera and Narendra Kumar (Defence Laboratory, Jodhpur) review stealth and camouflage technology

Much of the military nanotechnology information I stumble across is from the US, Canada, and/or Europe and while S. R. Vadera and Narendra Kumar (of India’s Defence Laboratory, Jodhpur [DLJ]) do offer some information about India’s military nanotechnology situation, they focus largely on the US, Canada, and Europe. Happily, their Jan. 30, 2014 Nanowerk Spotlight 6 pp. article titled, Nanotechnology and nanomaterials for camouflage and stealth applications offers a comprehensive review of the field,

This article briefly describes how nanomaterials and nanotechnology can be useful in the strategic area of camouflage and stealth technology. …

The word camouflage has its origin in the French word camoufler which means to disguise. In English dictionary, the word meaning was initially referred to concealment or disguise of military objects in order to prevent detection by the enemy. In earlier days, specifically before 20th century, the only sensor available to detect was human eye and so camouflage was confined to the visible light only. The rapid development of sensor technology outside the visible range has forced to use new definition and terminologies for camouflage.

Modern definition of camouflage may be given as “delay or deny detection of a military target by detectors operating over multispectral wavelength region of electromagnetic spectrum or non-electromagnetic radiation e.g., acoustic, magnetic, etc. Multispectral camouflage, low-observability, countermeasures, signature management, and stealth technology are some of the new terminologies used now instead of camouflage.

In modern warfare, stealth technology is applied mostly to aircrafts and combat weapons. Stealth technology can improve the survivability and performance of aircrafts and weapons to gain the upper hand. Stealth technology involves the minimization of acoustic, optical, infra-red, and electromagnetic signatures. Among them, the minimization of electromagnetic signature, particularly in microwave region, is the most important. It can be realized in several ways which include stealth shaping design, radar absorbing material (RAM), and radar absorbing structures (RAS)1.

Unexpectedly, there are multiple reference to Canadian stealth and camouflage technology all of them courtesy of one company, HyperStealth Biotechnology Corp. based in Maple Ridge, BC, Canada. mentioned in my Jan. 7, 2013 post about an invisibility cloak.

Getting back to the article, the authors have this to say about the international ‘stealth scene’,

Today virtually every nation and many non-state military organizations have access to advanced tactical sensors for target acquisition (radar and thermal imagers) and intelligence gathering surveillance systems (ground and air reconnaissance). Precision-guided munitions exist that can be delivered by artillery, missiles, and aircraft and that can operate in the IR [infra red] region of the electromagnetic spectrum. These advanced imaging sights and sensors allow enemies to acquire and engage targets through visual smoke, at night, and under adverse weather conditions.

To combat these new sensing and detection technologies, camouflage paint, paint additives, tarps, nets and foams have been developed for visual camouflage and thermal and radar signature suppression. …

One comment, thermal and radar signature suppression sounds like another way of saying ‘invisibility cloak’.

The authors also had something to say about the application of nanomaterials/nanotechnology,

Nanotechnology has significant influence over a set of many interrelated core skills of land forces like protection, engagement, detection, movements, communications and information collection together with interrelated warfare strategies. Additionally, nanotechnology also has its role in the development of sensor for warfare agents, tagging and tracking and destruction of CBRN [chemical, biological, radiological and nuclear] warfare agents, besides many other possible applications.

There’s a very interesting passage on ‘stealth coatings’ which includes this,

These new coatings can be attached to a wide range of surfaces and are the first step towards developing ‘shape shifting clothing’ capable of adapting to the environment around it. …

In another example, an Israeli company, Nanoflight has claimed to develop a new nano paint, which can make it near impossible to detect objects painted with the material. The company is continuing their efforts to extend the camouflage action of these paints in infrared region as well. BASF, Germany (uses polyisocynate dendrimer nanoparticles) and Isotronic Corporation, USA are among the very few agencies coming up with chemical agent resistant and innovative camouflage (CARC) coatings using nanomaterials. In India, paints developed by Defence Laboratory, Jodhpur (DLJ) using polymeric nanocomposites, nanometals and nanometal complexes are perhaps the first examples of multispectral camouflage paints tested in VIS-NIR and thermal infrared regions of the electromagnetic spectrum at system level. The nanocomposites developed by DLJ provide excellent scope for the tuning of reflectance properties both in visible and near infrared region6 of electromagnetic spectrum leading to their applications on military targets (Fig. 4).

For anyone interested in this topic, I recommend reading the article in its entirety.

One final note, I found this Wikipedia entry about the DLJ, (Note: A link has been removed)

Defence Laboratory (DLJ) is westernmost located, an strategically important laboratory of the Defence Research and Development Organisation (DRDO).

Its mission is development of Radio Communication Systems, Data links, Satellite Communication Systems, Millimeter Wave Communication systems. There are two divisions in laboratory

NRMA (Nuclear Radiation’s Management and Applications) Division
Camouflage Division

That’s all folks!

Chameleon materials

Harvard’s School of Engineering and Applied Sciences researchers discovered some unexpected properties when testing a new coating according to an Oct. 22, 2013 news item on Azonano,

Active camouflage has taken a step forward at the Harvard School of Engineering and Applied Sciences (SEAS), with a new coating that intrinsically conceals its own temperature to thermal cameras.

In a laboratory test, a team of applied physicists placed the device on a hot plate and watched it through an infrared camera as the temperature rose. Initially, it behaved as expected, giving off more infrared light as the sample was heated: at 60 degrees Celsius it appeared blue-green to the camera; by 70 degrees it was red and yellow. At 74 degrees it turned a deep red—and then something strange happened. The thermal radiation plummeted. At 80 degrees it looked blue, as if it could be 60 degrees, and at 85 it looked even colder. Moreover, the effect was reversible and repeatable, many times over.

The Oct. 21, 2013 Harvard University news release (also on EurekAlert), which originated the news item, discusses the potential for this discovery and describes the process of discovery in more detail (Note: A link has been removed),

Principal investigator Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at Harvard SEAS, predicts that with only small adjustments the coating could be used as a new type of thermal camouflage or as a kind of encrypted beacon to allow soldiers to covertly communicate their locations in the field.

The secret to the technology lies within a very thin film of vanadium oxide, an unusual material that undergoes dramatic electronic changes when it reaches a particular temperature. At room temperature, for example, pure vanadium oxide is electrically insulating, but at slightly higher temperatures it transitions to a metallic, electrically conductive state. During that transition, the optical properties change, too, which means special temperature-dependent effects—like infrared camouflage—can also be achieved.

The insulator-metal transition has been recognized in vanadium oxide since 1959. However, it is a difficult material to work with: in bulk crystals, the stress of the transition often causes cracks to develop and can shatter the sample. Recent advances in materials synthesis and characterization—especially those by coauthor Shriram Ramanathan, Associate Professor of Materials Science at Harvard SEAS—have allowed the creation of extremely pure samples of thin-film vanadium oxide, enabling a burst of new science and engineering to take off in just the last few years.

“Thanks to these very stable samples that we’re getting from Prof. Ramanathan’s lab, we now know that if we introduce small changes to the material, we can dramatically change the optical phenomena we observe,” explains lead author Mikhail Kats, a graduate student in Capasso’s group at Harvard SEAS. “By introducing impurities or defects in a controlled way via processes known as doping, modifying, or straining the material, it is possible to create a wide range of interesting, important, and predictable behaviors.”

By doping vanadium oxide with tungsten, for example, the transition temperature can be brought down to room temperature, and the range of temperatures over which the strange thermal radiation effect occurs can be widened. Tailoring the material properties like this, with specific outcomes in mind, may enable engineering to advance in new directions.

The researchers say a vehicle coated in vanadium oxide tiles could potentially mimic its environment like a chameleon, appearing invisible to an infrared camera with only very slight adjustments to the tiles’ actual temperature—a far more efficient system than the approaches in use today.

Tuned differently, the material could become a component of a secret beacon, displaying a particular thermal signature on cue to an infrared surveillance camera. Capasso’s team suggests that the material could be engineered to operate at specific wavelengths, enabling simultaneous use by many individually identifiable soldiers.

And, because thermal radiation carries heat, the researchers believe a similar effect could be employed to deliberately speed up or slow down the cooling of structures ranging from houses to satellites.

The Harvard team’s most significant contribution is the discovery that nanoscale structures that appear naturally in the transition region of vanadium oxide can be used to provide a special level of tunability, which can be used to suppress thermal radiation as the temperature rises. The researchers refer to such a spontaneously structured material as a “natural, disordered metamaterial.”

“To artificially create such a useful three-dimensional structure within a material is extremely difficult,” says Capasso. “Here, nature is giving us what we want for free. By taking these natural metamaterials and manipulating them to have all the properties we want, we are opening up a new area of research, a completely new direction of work. We can engineer new devices from the bottom up.”

Here’s an image, from the scientists, illustrating the material’s thermal camouflage (or chameleon) properties,

A new coating intrinsically conceals its own temperature to thermal cameras. (Image courtesy of Mikhail Kats.)

A new coating intrinsically conceals its own temperature to thermal cameras. (Image courtesy of Mikhail Kats.)

Here’s a link to and a citation for the research paper,

Vanadium Dioxide as a Natural Disordered Metamaterial: Perfect Thermal Emission and Large Broadband Negative Differential Thermal Emittance by Mikhail A. Kats, Romain Blanchard, Shuyan Zhang, Patrice Genevet, Changhyun Ko, Shriram Ramanathan, and Federico Capasso. Phys. Rev. X » Volume 3 » Issue 4  or Phys. Rev. X 3, 041004 (2013) DOI:10.1103/PhysRevX.3.041004

This paper is published in an open access journal according to the Harvard news release,

About Physical Review X

Launched in August 2011, PRX (http://prx.aps.org) is an open-access, peer-reviewed publication of the American Physical Society (www.aps.org), a non-profit membership organization working to advance and diffuse the knowledge of physics through its outstanding research journals, scientific meetings, and education, outreach, advocacy and international activities. APS represents 50,000 members, including physicists in academia, national laboratories and industry in the United States and throughout the world.

Watch out Roomba! Camouflaging soft robots are on the move

Roomba, one of the better known consumer-class robots, is a hard-bodied robot used for vacuum-cleaning (or, hoovering as the Brits say). These days scientists are working on soft-bodied robots modeled on an octopus or a starfish or a squid. A team at Harvard University has added a camouflaging feature to its soft robot.

The Aug. 16, 2012 news release on EurekAlert provides some detail about the inspiration (in a field generally known as biomimicry or biomimetics),

A team of researchers led by George Whitesides, the Woodford L. and Ann A. Flowers University Professor [and well known within the field of nanotechnology], has already broken new engineering ground with the development of soft, silicone-based robots inspired by creatures like starfish and squid.

Now, they’re working to give those robots the ability to disguise themselves.

“When we began working on soft robots, we were inspired by soft organisms, including octopi and squid,” Morin said [Stephen Morin, a Post-Doctoral Fellow and first author for the paper]. “One of the fascinating characteristics of these animals is their ability to control their appearance, and that inspired us to take this idea further and explore dynamic coloration. I think the important thing we’ve shown in this paper is that even when using simple systems – in this case we have simple, open-ended micro-channels – you can achieve a great deal in terms of your ability to camouflage an object, or to display where an object is.”

“One of the most interesting questions in science is ‘Why do animals have the shape, and color, and capabilities that they do?'” said Whitesides. “Evolution might lead to a particular form, but why? One function of our work on robotics is to give us, and others interested in this kind of question, systems that we can use to test ideas. Here the question might be: ‘How does a small crawling organism most efficiently disguise (or advertise) itself in leaves?’ These robots are test-beds for ideas about form and color and movement.”

Peter Reuell’s Aug. 16, 2012 article for Harvard Science, which originated the news release, describes some of the technology and capabilities,

Just as with the soft robots, the “color layers” used in the camouflage start as molds created using 3-D printers. Silicone is then poured into the molds to create micro-channels, which are topped with another layer of silicone. The layers can be created as a separate sheet that sits atop the soft robots, or incorporated directly into their structure. Once created, researchers can pump colored liquids into the channels, causing the robot to mimic the colors and patterns of its environment.

The system’s camouflage capabilities aren’t limited to visible colors though.

By pumping heated or cooled liquids into the channels, researchers can camouflage the robots thermally (infrared color). Other tests described in the Science [journal]  paper used fluorescent liquids that allowed the color layers to literally glow in the dark.

“There is an enormous amount of spectral control we can exert with this system,” Morin said. “We can design color layers with multiple channels, which can be activated independently. We’ve only begun to scratch the surface, I think, of what’s possible.”

The uses for the color-layer technology, however, don’t end at camouflage.

Just as animals use color change to communicate, Morin envisions robots using the system as a way to signal their position, both to other robots, and to the public. As an example, he cited the possible use of the soft machines during search and rescue operations following a disaster. In dimly lit conditions, he said, a robot that stands out from its surroundings (or even glows in the dark) could be useful in leading rescue crews trying to locate survivors.

So,  if the scientists are pumping the colour into the soft robot, it’s still a long way from nature’s design where the creature produces its own colourants and controls its own camouflage in response to environmental factors.

Interestingly, there’s no mention of military applications for this camouflaging robot.

Camouflage for everyone

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).