Caption: These tangram puzzles are made from a new type of edible cellulose-based plastic with colors provided by tiny nanostructures within the material, rather than dyes. Credit: Adapted from ACS Nano 2025, DOI: 10.1021/acsnano.5c05346
Plastics are one of the largest sources of pollution on Earth, lasting for years on land or in water. But a new type of brilliantly colored cellulose-based plastic detailed in ACS Nano could change that. By adding citric acid and squid ink to a cellulose-based polymer, researchers created a variety of structurally colored plastics that were comparable in strength to traditional plastics, but made from natural biodegradable ingredients and easily recycled using water.
Many plastics are dyed using specialized colorants, which can make these materials hard to recycle using typical processes. Over time, dyes can fade or leach into the environment, posing risks to wildlife. One way to make these colorants largely unnecessary could be a phenomenon called structural color. This occurs when tiny structures in a material reflect certain wavelengths of light rather than a dye or pigment molecule. Structural color gives peacock feathers and butterfly wings their vibrant hues and dazzling shine, but certain synthetic polymers display structural color as well.
Hydroxypropyl cellulose (HPC), a derivative of cellulose often used in foods and pharmaceuticals, is one example of a material that can display structural color. In liquid form, it shines in iridescent tones, but its chemical properties have historically made it difficult to form into a solid plastic. So, Lei Hou, Peiyi Wu and colleagues wanted to see if they could fine-tune the chemistry of HPC to create vibrant, structurally colored plastics that worked as well as existing petroleum-based plastics and were environmentally friendly.
The researchers added citric acid, squid ink powder and water to the HPC polymer, which formed additional hydrogen bonds within the polymer, creating a firm material as it air-dried at room temperature. The dried material’s final hue depended on the amount of citric acid, so the researchers were able to create blue, green, orange and red versions. The final color intensity depended on the amount of squid ink powder present. Next, this liquid formulation was 3D-printed into a variety of shapes, molded into small structures, formed into a thin film and gently folded into pinwheels and origami cranes.
Because the plastics dissolved in water, the original HPC-based plastic could be reformed into new shapes after being dried again. The recycled plastic had mechanical properties that were comparable or superior to those of most commercial, newly manufactured plastics. This work provides an efficient strategy to develop the next-generation of sustainable, dye-free plastics , the researchers say.
The authors acknowledge funding from the Fundamental Research Funds for the Central Universities, the National Natural Science Foundation of China, and the Research Foundation of the National Innovation Center of Advanced Dyeing & Finishing Technology.
A July 9, 2025 news item on Nanowerk highlights a quality not often associated with sharks and one of my favourite topics, structural colour,
New research into the anatomy of blue sharks (Prionace glauca) reveals a unique nanostructure in their skin that produces their iconic blue colouration, but intriguingly, also suggests a potential capacity for colour change.
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Caption: Blue shark dermal denticles. Credit: Dr Viktoriia Kamska
“Blue is one of the rarest colours in the animal kingdom, and animals have developed a variety of unique strategies through evolution to produce it, making these processes especially fascinating,” says Dr Viktoriia Kamska, a post-doctoral researcher in the lab of Professor Mason Dean at City University of Hong Kong.
The team revealed that the secret to the shark’s colour lies in the pulp cavities of the tooth-like scales — known as dermal denticles— that armour the shark’s skin. The key features of this colour-producing mechanism inside the pulp cavity are guanine crystals, which act as blue reflectors, alongside melanin-containing vesicles called melanosomes, which act as absorbers of other wavelengths. “These components are packed into separate cells, reminiscent of bags filled with mirrors and bags with black absorbers, but kept in close association so they work together,” explains Dr. Kamska. As a result, a pigment (melanin) collaborates with a structured material (guanine platelets of specific thickness and spacing) to enhance colour saturation.
“When you combine these materials together, you also create a powerful ability to produce and change colour,” says Professor Dean. “What’s fascinating is that we can observe tiny changes in the cells containing the crystals and see and model how they influence the colour of the whole organism.”
This anatomical breakthrough was made possible using a mixture of fine-scale dissection, optical microscopy, electron microscopy, spectroscopy, and a suite of other imaging techniques to characterise the form, function, and architectural arrangements of the colour-producing nanostructures. “We started looking at colour at the organismal level, on the scale of metres and centimetres, but structural colour is achieved at the nanometer scale, so we have to use a range of different approaches,” says Professor Dean.
Identifying the likely nanoscale culprits behind the shark’s blue colour was only part of the equation. Dr Kamska and her collaborators also used computational simulations to confirm which architectural parameters of these nanostructures are responsible for producing the specific wavelengths of the observed spectral appearance. “It’s challenging to manually manipulate structures at such a small scale, so these simulations are incredibly useful for understanding what colour palette is available,” says Dr Kamska.
The discovery also reveals that the shark’s trademark colour is potentially mutable through tiny changes in the relative distances between layers of guanine crystals within the denticle pulp cavities. Whereas narrower spaces between layers create the iconic blues, increasing this space shifts the colour into greens and golds.
Dr Kamska and her team have demonstrated that this structural mechanism of colour change could be driven by environmental factors that affect guanine platelet spacing. “In this way, very fine scale alterations resulting from something as simple as humidity or water pressure changes could alter body colour, that then shape how the animal camouflages or counter-shades in its natural environment,” says Professor Dean.
For example, the deeper a shark swims, the more pressure that their skin is subjected to, and the tighter the guanine crystals would likely be pushed together – which should darken the shark’s colour to better suit its surroundings. “The next step is to see how this mechanism really functions in sharks living in their natural environment,” says Dr Kamska.
While this research provides important new insights into shark anatomy and evolution, it also has a strong potential for bio-inspired engineering applications. “Not only do these denticles provide sharks with hydrodynamic and antifouling benefits, but we’ve now found that they also have a role in producing and maybe changing colour too,” says Professor Dean. “Such a multi-functional structural design —a marine surface combining features for high-speed hydrodynamics and camouflaging optics— as far as we know, hasn’t been seen before.”
Therefore, this discovery could have implications for improving environmental sustainability within the manufacturing industry. “A major benefit of structural colouration over chemical colouration is that it reduces the toxicity of materials and reduces environmental pollution,” says Dr Kamska. “Structural colour is a tool that could help a lot, especially in marine environments, where dynamic blue camouflage would be useful.”
“As nanofabrication tools get better, this creates a playground to study how structures lead to new functions,” says Professor Dean. “We know a lot about how other fishes make colours, but sharks and rays diverged from bony fishes hundreds of millions of years ago – so this represents a completely different evolutionary path for making colour.”
This research, funded by Hong Kong’s University Grants Committee, General Research Fund, is being presented at the Society for Experimental Biology Annual Conference in Antwerp, Belgium on the 9th July 2025.
Natural materials that have evolved in plants and animals often display spectacular mechanical and optical properties. For example, spider silk is as strong as steel and tougher than Kevlar, which is used in bullet-proof vests. Inspired by nature, chemists are now synthesizing materials that mimic the structures and properties of shells, bones, muscle, leaves, feathers, and other natural materials. In this talk, I will discuss our recent discovery of a new type of coloured glass that is a mimic of beetle shells. [emphasis mine] These new materials have intriguing optical properties that arise from their twisted internal structure, and they may be useful for emerging applications..
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At the talk, MacLachlan mentioned that his new structurally iridescent material received great interest from the architectural community but since producing it was a painstaking process for a minute quantity, it would not be suitable as a building material.
A few years later I stumbled across some work at Cornell University where material scientists and Korean artist Kimsooja were working on what looks like an iridescent art/science piece, from a September 15, 2014 posting,
For her newest work, Korean artist Kimsooja wanted to explore a “shape and perspective that reveals the invisible as visible, physical as immaterial, and vice versa.” As artist-in-residence for the Cornell Council for the Arts’ (CCA) 2014 Biennial, she has realized that objective with “A Needle Woman: Galaxy was a Memory, Earth is a Souvenir,” to be installed on the Arts Quad next week [Sept. 15 – 19, 2014]. It will be one of several installations on campus for the semester-long biennial, “Intimate Cosmologies: The Aesthetics of Scale in an Age of Nanotechnology,” beginning Sept. 18 [2014] with a talk by Kimsooja.
Here’s how ‘Needle Woman’ looked after fabrication,
Jaeho Chong Pieces of Kimsooja’s “Needle Woman” artwork during fabrication in Shanghai show the polymer film developed by Cornell researchers
Creating materials that change color based on viewing angle represents a significant challenge at the intersection of art and science. Natural examples of this phenomenon, called iridescence, appear in butterfly wings, peacock feathers, and opals. Unlike traditional pigments that absorb specific wavelengths of light, these natural materials use microscopic structures to split light into different colors. This “structural color” approach creates pure, vibrant hues that don’t fade over time and require no potentially toxic pigments.
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A collaboration between Cornell University materials scientists and Korean-American artist Kimsooja has now yielded a practical solution to this challenge. The team developed a method for creating large-scale, durable iridescent coatings, demonstrated through a 46-foot-tall architectural installation titled A Needle Woman: Galaxy was a Memory, Earth is a Souvenir. Initially exhibited at Cornell under the auspices of the Cornell Council for the Arts, the installation now stands as part of the permanent collection at Yorkshire Sculpture Park in Wakefield, UK, where it has maintained its striking optical properties for over a decade.
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The breakthrough relies on custom-designed plastic molecules that automatically arrange themselves into regular patterns. These molecules consist of two different types of plastic chemically bonded together – polystyrene and poly(tert-butyl methacrylate). When properly designed, thousands of these dual-component molecules spontaneously stack into alternating layers, creating a natural grating that splits light into different colors.
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The key innovation came in synthesizing these molecules at unprecedented sizes – about 1000 times longer than typical plastic molecules. At this scale, the self-assembled layers naturally form patterns around 300-400 nanometers in spacing, large enough to interact with visible light. The researchers then developed a precise coating method to apply these materials while maintaining their self-organized structure.
The scale-up process presented numerous challenges. Each production batch yielded only about 35-40 grams of usable material, with half the attempts failing due to the extreme sensitivity to air and water during synthesis. The installation required roughly 500 grams of material to coat all panels. The team developed a custom two-liter reactor equipped with specialized mixing equipment to increase production scale while maintaining precise control over reaction conditions.
Color consistency posed another challenge. Different batches of the polymer produced slightly different colors due to variations in molecular size. The researchers developed two solutions: blending multiple batches to achieve consistent colors and adding precise amounts of shorter polymer chains to fine-tune the optical properties.
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The team also solved the challenge of applying these coatings to curved surfaces through a specialized lamination technique. They first created the color-shifting layer on flat, flexible plastic sheets, then sandwiched it between protective layers before carefully adhering it to curved acrylic panels. This approach preserved the optical properties while protecting the coating from environmental damage.
Molecules to Masterpieces: Bridging Materials Science and the Arts by Ferdinand F. E. Kohle, Hiroaki Sai, William R. T. Tait, Peter A. Beaucage, Ethan M. Susca, R. Paxton Thedford, Ulrich B. Wiesner. Advanced Materials DOI: https://doi.org/10.1002/adma.202413939. First published online: 05 December 2024
The UCF-developed plasmonic paint uses nanoscale structural arrangement of colorless materials — aluminum and aluminum oxide — instead of pigments to create colors. Here the plasmonic paint is applied to the wings of metal butterflies, the insect that inspired the research. Credit: University of Central Florida
A March 9, 2023 news item on Nanowerk announces research into multicolour energy-saving coating/paint, so, this is a structural colour story, Note: Links have been removed,
University of Central Florida researcher Debashis Chanda, a professor in UCF’s NanoScience Technology Center, has drawn inspiration from butterflies to create the first environmentally friendly, large-scale and multicolor alternative to pigment-based colorants, which can contribute to energy-saving efforts and help reduce global warming.
“The range of colors and hues in the natural world are astonishing — from colorful flowers, birds and butterflies to underwater creatures like fish and cephalopods,” Chanda says. “Structural color serves as the primary color-generating mechanism in several extremely vivid species where geometrical arrangement of typically two colorless materials produces all colors. On the other hand, with manmade pigment, new molecules are needed for every color present.”
Based on such bio-inspirations, Chanda’s research group innovated a plasmonic paint, which utilizes nanoscale structural arrangement of colorless materials — aluminum and aluminum oxide — instead of pigments to create colors.
While pigment colorants control light absorption based on the electronic property of the pigment material and hence every color needs a new molecule, structural colorants control the way light is reflected, scattered or absorbed based purely on the geometrical arrangement of nanostructures.
Such structural colors are environmentally friendly as they only use metals and oxides, unlike present pigment-based colors that use artificially synthesized molecules.
The researchers have combined their structural color flakes with a commercial binder to form long-lasting paints of all colors.
“Normal color fades because pigment loses its ability to absorb photons,” Chanda says. “Here, we’re not limited by that phenomenon. Once we paint something with structural color, it should stay for centuries.”
Additionally, because plasmonic paint reflects the entire infrared spectrum, less heat is absorbed by the paint, resulting in the underneath surface staying 25 to 30 degrees Fahrenheit cooler than it would if it were covered with standard commercial paint, the researcher says.
“Over 10% of total electricity in the U.S. goes toward air conditioner usage,” Chanda says. “The temperature difference plasmonic paint promises would lead to significant energy savings. Using less electricity for cooling would also cut down carbon dioxide emissions, lessening global warming.”
Plasmonic paint is also extremely lightweight, the researcher says.
This is due to the paint’s large area-to-thickness ratio, with full coloration achieved at a paint thickness of only 150 nanometers, making it the lightest paint in the world, Chanda says.
The paint is so lightweight that only about 3 pounds of plasmonic paint could cover a Boeing 747, which normally requires more than 1,000 pounds of conventional paint, he says.
Chanda says his interest in structural color stems from the vibrancy of butterflies.
“As a kid, I always wanted to build a butterfly,” he says. “Color draws my interest.”
Future Research
Chanda says the next steps of the project include further exploration of the paint’s energy-saving aspects to improve its viability as commercial paint.
“The conventional pigment paint is made in big facilities where they can make hundreds of gallons of paint,” he says. “At this moment, unless we go through the scale-up process, it is still expensive to produce at an academic lab.”
“We need to bring something different like, non-toxicity, cooling effect, ultralight weight, to the table that other conventional paints can’t.” Chanda says.
Licensing Opportunity
For more information about licensing this technology, please visit the Inorganic Paint Pigment for Vivid Plasmonic Color technology sheet.
Researcher’s Credentials
Chanda has joint appointments in UCF’s NanoScience Technology Center, Department of Physics and College of Optics and Photonics. He received his doctorate in photonics from the University of Toronto and worked as a postdoctoral fellow at the University of Illinois at Urbana-Champaign. He joined UCF in Fall 2012.
Here’s a link to and a citation for the paper,
Ultralight plasmonic structural color paint by Pablo Cencillo-Abad, Daniel Franklin, Pamela Mastranzo-Ortega, Javier Sanchez-Mondragon, and Debashis Chanda. Science Advances 8 Mar 2023 Vol 9, Issue 10 DOI: 10.1126/sciadv.adf7207
This paper is open access.
Here’s the researcher with one of ‘his butterflies’ (I may be reading a little too much into this but it looks like he’s uncomfortable having his photo taken but game to do it for work that he’s proud of),
Caption: Debashis Chanda, a professor in UCF’s NanoScience Technology Center, drew inspiration from butterflies to create the innovative new plasmonic paint, shown here applied to metal butterfly wings. Credit: University of Central Florida
The brilliant and often iridescent colours that we see in some species of birds, beetles and butterflies arise from a regular arrangement of nanostructures that scatter selective wavelengths of light more strongly to generate colour. These colours are called structural colours, which usually range from blues to greens, and even magenta. However, vibrant or saturated reds are elusive and notably absent from the structural colour range in both natural and synthetic realms.
To achieve highly saturated reds, the material needs to absorb light from all wavelengths shorter than ~600 nm and reflect the remaining longer wavelengths, doing both as completely as possible. This sharp transition from absorption to reflection was prescribed theoretically by none other than Erwin Schrödinger of quantum theory fame. However, the physics of resonators tell us that high-order optical resonances in blue will also occur as soon as we have a fundamental resonance in red. This combination of blue and red thus results in the magenta observed in nature. It is therefore challenging to achieve the Schrödinger’s red pixel, which would produce the most saturated red in the world. Current nanoantenna-based approaches are insufficient to simultaneously satisfy the above conditions.
Researchers from the Agency for Science, Technology and Research’s (A*STAR) Institute of Materials Research and Engineering (IMRE), National University of Singapore (NUS) and Singapore University of Technology and Design (SUTD) have collaborated to design and realise reds at the ultimate limit of saturation as predicted by theory, where the team worked together on conceptualisation methodology, fabrications, characterisations and simulations. This research was published in Science Advances on 23 February 2022.
The design consists of regularly arranged silicon nanoantennas in the shape of ellipses. These produce possibly the most saturated and brightest reds with ~80% reflectance, exceeding the reds in the standard red, green and blue gamut (sRGB) and other well-known red pigments, e.g. cadmium red … .
The nanoantennas support two partially overlapping quasi bound-states-in-the-continuum modes, where the optimal dimensions of the silicon nanoantenna arrays are derived by using a gradient descent algorithm to enable the antennas to achieve sharp spectral edges at red wavelengths. At the same time, high-order modes at blue or green wavelengths are suppressed via engineering the substrate‑induced diffraction channels and the absorption of amorphous silicon.
Potential uses for Schrödinger’s red include developing a polarisation dependent encryption method, with plans to scale up the Schrödinger’s red pixel for applications like functional nanofabrication devices such as optical spectrometers and reflective displays with high colour saturation.
“With this new design that can achieve the most saturated and brightest reds, we can exploit its sensitivity to polarisation and illumination angle on potential applications for information encryption. This proposed concept and design methodology could also be generalised to other Schrödinger’s colour pixels. The highly-saturated red achieved could be potentially scaled up through methods such as deep ultraviolet and nano-imprint lithography, to reach the dimensions of reflective displays based on multilayer film configuration, which could lead to potential applications like compact red filters, highly saturated reflective displays, nonlocal metasurfaces, and miniaturised spectrometers”, said Dr. Dong Zhaogang, Deputy Department Head of Nanofabrication at A*STAR’s IMRE.
“The creation of the record-high saturation and brightness in red opens up possibilities for a plethora of applications related to anti-counterfeiting technologies, high-calibre colour display and more, which were previously perceived as unachievable with structural colour. It showcases a wonderful synergy between conceptual breakthrough, powerful algorithm and advanced nanofabrication”, said Prof. Cheng-Wei Qiu, Dean’s Chair Professor at NUS.
“This work in structural colours goes to show that we can sometimes outdo evolution through clever use of the tools in nanofabrication and accurate optical simulations”, said Prof. Joel Yang, Provost Chair Professor and Associate Professor in Engineering Product Development at SUTD.
Here’s a link to and a citation for the paper,
Schrödinger’s red pixel by quasi-bound-states-in-the-continuum by Zhaogang Dong, Lei Jin, Soroosh Daqiqeh Rezaei, Hao Wang, Yang Chen, Febiana Tjiptoharsono, Jinfa Ho, Sergey Gorelik, Ray Jia Hong Ng, Qifeng Ruan, Cheng-Wei Qiu and Joel K. W. Yang. Science Advances Vol 8, Issue 8 DOI: 10.1126/sciadv.abm4512 Published 23 Feb 2022
This paper is open access.
Math error, colour theory, and perception
An August 10, 2022 news item on phys.org announced a math error made by Erwin Schrödinger and others,
A new study corrects an important error in the 3D mathematical space developed by the Nobel Prize-winning physicist Erwin Schrödinger and others, and used by scientists and industry for more than 100 years to describe how your eye distinguishes one color from another. The research has the potential to boost scientific data visualizations, improve TVs and recalibrate the textile and paint industries.
“The assumed shape of color space requires a paradigm shift,” said Roxana Bujack, a computer scientist with a background in mathematics who creates scientific visualizations at Los Alamos National Laboratory. Bujack is lead author of the paper by a Los Alamos team in the Proceedings of the National Academy of Sciences on the mathematics of color perception.
“Our research shows that the current mathematical model of how the eye perceives color differences is incorrect. That model was suggested by Bernhard Riemann and developed by Hermann von Helmholtz and Erwin Schrödinger—all giants in mathematics and physics—and proving one of them wrong is pretty much the dream of a scientist,” said Bujack.
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While the Los Alamos National Laboratory work was published in April 2022 (online) and May 2022 (in print), their news announcement doesn’t seem to have been made until August. I can’t be certain but I believe this should have an impact on the work from A*STAR as that team’s paper cites: E. Schrödinger, Theorie der Pigmente von größter Leuchtkraft. Ann. Phys.367, 603–622 (1920).
Modeling human color perception enables automation of image processing, computer graphics and visualization tasks.
“Our original idea was to develop algorithms to automatically improve color maps for data visualization, to make them easier to understand and interpret,” Bujack said. So the team was surprised when they discovered they were the first to determine that the longstanding application of Riemannian geometry, which allows generalizing straight lines to curved surfaces, didn’t work.
To create industry standards, a precise mathematical model of perceived color space is needed. First attempts used Euclidean spaces—the familiar geometry taught in many high schools; more advanced models used Riemannian geometry. The models plot red, green and blue in the 3D space. Those are the colors registered most strongly by light-detecting cones on our retinas, and—not surprisingly—the colors that blend to create all the images on your RGB computer screen.
In the study, which blends psychology, biology and mathematics, Bujack and her colleagues discovered that using Riemannian geometry overestimates the perception of large color differences. That’s because people perceive a big difference in color to be less than the sum you would get if you added up small differences in color that lie between two widely separated shades.
Riemannian geometry cannot account for this effect.
“We didn’t expect this, and we don’t know the exact geometry of this new color space yet,” Bujack said. “We might be able to think of it normally but with an added dampening or weighing function that pulls long distances in, making them shorter. But we can’t prove it yet.”
Here’s a link to and a citation for the paper,
The non-Riemannian nature of perceptual color space by Roxana Bujack, Emily Teti, Jonah Miller, Elektra Caffrey, and Terece L. Turton. Proceedings of the National Academy of Sciences (PNAS) 119 (18) e2119753119 DOI: https://doi.org/10.1073/pnas.2119753119 Published: April 29, 2022
Bacteria interacting with four different topographies Courtesy: Imperial College London
A February 9, 2022 news item on phys.org describes some bioinspired research that could help cut down on the use of disinfectants,
Researchers have created intricately patterned materials that mimic antimicrobial, adhesive and drag reducing properties found in natural surfaces.
The team from Imperial College London found inspiration in the wavy and spiky surfaces found in insects, including on cicada and dragonfly wings, which ward off bacteria.
They hope the new materials could be used to create self-disinfecting surfaces and offer an alternative to chemically functionalized surfaces and cleaners, which can promote the growth of antibiotic-resistant bacteria.
The tiny waves, which overlap at defined angles to create spikes and ripples, could also help to reduce drag on marine transport by mimicking shark skin, and to enhance the vibrancy of color without needing pigment, by mimicking insects.
Senior author Professor Joao Cabral, of Imperial’s Department of Chemical Engineering, said, “It’s inspiring to see in miniscule detail how the wings and skins of animals help them master their environments. Animals evolved wavy surfaces to kill bacteria, enhance color, and reduce drag while moving through water. We’re borrowing these natural tricks for the very same purposes, using a trick reminiscent of a Fourier wave superposition.”
Spiky structures
Researchers created the new materials by stretching and compressing a thin, soft, sustainable plastic resembling clingfilm to create three-dimensional nano- and microscale wavy patterns, compatible with sustainable and biodegradable polymers.
The spiky structure was inspired by the way insects and fish have evolved to interact with their environments. The corrugated ripple effect is seen in the wings of cicadas and dragonflies, whose surfaces are made of tiny spikes which pop bacterial cells to keep the insects clean.
The structure could also be applied to ships to reduce drag and boost efficiency – an application inspired by shark skin, which contains nanoscale horizontal ridges to reduce friction and drag.
Another application is in producing vibrant colours like those seen in the wings of morpho blue butterflies, whose cells are arranged to reflect and bend light into a brilliant blue without using pigment. Known as structural colour, other examples include the blue in peacock feathers, the shells of iridescent beetles, and blue human eyes.
They discovered that they could recreate these naturally occurring surface waves by stretching and then relaxing thin polymer skins in precise directions at the nanoscale.
While complex patterns can be fabricated by lithography and other methods, for instance in silicon microchip production, these are generally prohibitively expensive to use over large areas. This new technique, on the other hand, is ready to be scaled up relatively inexpensively if confirmed to be effective and robust.
Potential applications include self-disinfecting surfaces in hospitals, schools, public transport, and food manufacturing. They could even help keep medical implants clean, which is important as these can host networks of bacterial matter known as biofilms that are notoriously difficult to kill.
Naturally occurring wave patterns are also seen in the wrinkling of the human brain and fingertips as well as the ripples in sand beds. First author Dr Luca Pellegrino from the Department of Chemical Engineering, said: “The idea is compelling because it is simple: by mimicking the surface waves found in nature, we can create a palette of patterns with important applications. Through this work we can also learn more about the possible origins of these natural forms – a field called morphogenesis.”
he next focus for the team is to test the effectiveness and robustness of the material in real-world settings, like on bus surfaces. The researchers hope it can contribute to solutions to surface cleanliness that are not reliant on chemical cleaners. To this end, they have been awarded a €5.4million EU HORIZON grant with collaborators ranging from geneticists at KU Leuven to a bus manufacturer to develop sustainable and robust antimicrobial surfaces for high traffic contexts.
Here’s a link (the press release also has a link) to and a citation for the paper,
This work reminds me of Sharklet, a company that was going to produce materials that mimicked the structure of sharkskin. Apparently, sharks have nanostructures on their skin which prevents bacteria and more from finding a home there.
I was expecting a news release mentioning some of the smaller scales at which scientists work, e.g., micro, nano, pico, femto, etc. That was not the case.
The American Chemical Society (ACS) is producing a new, biweekly science podcast called Tiny Matters, which is available wherever you listen to podcasts. Head to ACS’ website or your favorite platform and subscribe.
The first episode drops today. Hosts Sam Jones, Ph.D., and Deboki Chakravarti, Ph.D., chat with experts about the ancient beasts that went extinct 65 million years ago, but whose remains still captivate us today — dinosaurs. Scientists around the world regularly discover new fossils, and that helps piece together the mystery of what dinosaurs and other extinct creatures were like. That information doesn’t just inspire movies like “Jurassic Park”; it also helps researchers predict Earth’s future and could even lead to more sustainable technology.
Tiny Matters is a science podcast about things small in size but big in impact. Every other Wednesday, the hosts will uncover little stuff that makes big stuff possible. Upcoming episodes will find them answering questions such as “How does our brain form memories?”, “Why haven’t we terraformed Mars yet?” and “Why isn’t there a vaccine for HIV?” Tune in!
The American Chemical Society (ACS) is a nonprofit organization chartered by the U.S. Congress. ACS’ mission is to advance the broader chemistry enterprise and its practitioners for the benefit of Earth and all its people. The Society is a global leader in promoting excellence in science education and providing access to chemistry-related information and research through its multiple research solutions, peer-reviewed journals, scientific conferences, eBooks and weekly news periodical Chemical & Engineering News. ACS journals are among the most cited, most trusted and most read within the scientific literature; however, ACS itself does not conduct chemical research. As a leader in scientific information solutions, its CAS division partners with global innovators to accelerate breakthroughs by curating, connecting and analyzing the world’s scientific knowledge. ACS’ main offices are in Washington, D.C., and Columbus, Ohio.
I was not expecting dinosaurs and fossils. So, I listened.
First, it’s not that easy to define what a fossil is. (I had no idea this was a problem.) And, the hosts interview a scientist who studies what happens to fossils at the molecular level, which in this case means DNA (deoxyribonucleic acid) and proteins. it;s a field known as molecular taphonomy.
I found the programme fascinating (scientists think dinosaurs were feathered; they mention evolutionary photonics and structural colour). This despite the fact I’m not very interested in dinosaurs or fossils. Bravo to the hosts for keeping it interesting and light while providing lots of technical information.
(I imagine that the excessive perkiness and multiple declarations that something or other is cool are a consequence of nerves when recording the first episode in a brand new podcast series.)
Getting back to the strengths, the hosts (Jones and Chakravarti) have taken some very technical material and found a way to describe it without patronizing the listener or making it impossible to understand.
For people who prefer to read, there’s a transcript of the first episode here. The scientists interviewed in the “Dinosaur Fossils: Inspiring Jurassic Park and helping us predict Earth’s future” episode were Caitlin Colleary, a paleontologist at the Cleveland Museum of Natural History (Ohio), Emma Dunne, a paleobiologist at University of Birmingham (England), and Vinod Saranathan, a physicist and evolutionary biologist at Yale-NUS [National University of Singapore] College in Singapore.
The flower beetle Torynorrhina flammea. [downloaded from https://www.nanowerk.com/nanotechnology-news2/newsid=58269.php]
That is one gorgeous beetle and a June 17, 2021 news item on Nanowerk reveals that it features in a structural colour story (i.e, how structures rather than pigments create colour),
The unique mechanical and optical properties found in the exoskeleton of a humble Asian beetle has the potential to offer a fascinating new insight into how to develop new, effective bio-inspired technologies.
Pioneering new research by a team of international scientists, including Professor Pete Vukusic from the University of Exeter, has revealed a distinctive, and previously unknown property within the carapace of the flower beetle – a member of the scarab beetle family.
The study showed that the beetle has small micropillars within the carapace – or the upper section of the exoskeleton – that give the insect both strength and flexibility to withstand damage very effectively.
Crucially, these micropillars are incorporated into highly regular layering in the exoskeleton that concurrently give the beetle an intensely bright metallic colour appearance.
For this new study, the scientists used sophisticated modelling techniques to determine which of the two functions – very high mechanical strength or conspicuously bright colour – were more important to the survival of the beetle.
They found that although these micropillars do create a highly enhanced toughness of the beetle shell, they were most beneficial for optimising the scattering of coloured light that generates its conspicuous appearance.
The research is published this week in the leading journal, Proceedings of the National Academy of Sciences, PNAS.
Professor Vukusic, one of three leads of the research along with Professor Li at Virginia Tech and Professor Kolle at MIT [Massachusetts Institute of Technology], said: “The astonishing insights generated by this research have only been possible through close collaborative work between Virginia Tech, MIT, Harvard and Exeter, in labs that trailblaze the fields of materials, mechanics and optics. Our follow-up venture to make use of these bio-inspired principles will be an even more exciting journey.”.
The seeds of the pioneering research were sown more than 16 years ago as part of a short project created by Professor Vukusic in the Exeter undergraduate Physics labs. Those early tests and measurements, made by enthusiastic undergraduate students, revealed the possibility of intriguing multifunctionality.
The original students examined the form and structure of beetles’ carapce to try to understand the simple origin of their colour. They noticed for the first time, however, the presence of strength-inducing micropillars.
Professor Vukusic ultimately carried these initial findings to collaborators Professor Ling Li at Virginia Tech and Professor Mathias Kolle at Harvard and then MIT who specialise in the materials sciences and applied optics. Using much more sophisticated measurement and modelling techniques, the combined research team were also to confirm the unique role played by the micropillars in enhancing the beetles’ strength and toughness without compromising its intense metallic colour.
The results from the study could also help inspire a new generation of bio-inspired materials, as well as the more traditional evolutionary research.
By understanding which of the functions provides the greater benefit to these beetles, scientists can develop new techniques to replicate and reproduce the exoskeleton structure, while ensuring that it has brilliant colour appearance with highly effective strength and toughness.
Professor Vukusic added: “Such natural systems as these never fail to impress with the way in which they perform, be it optical, mechanical or in another area of function. The way in which their optical or mechanical properties appear highly tolerant of all manner of imperfections too, continues to offer lessons to us about scientific and technological avenues we absolutely should explore. There is exciting science ahead of us on this journey.”
Caption: Light hits the 3-D printed nanostructures from below. After it is transmitted through, the viewer sees only green light — the remaining colors are redirected. Credit: Thomas Auzinger [downloaded from http://visualcomputing.ist.ac.at/publications/2018/StructCol/]
Most of the objects we see are colored by pigments, but using pigments has disadvantages: such colors can fade, industrial pigments are often toxic, and certain color effects are impossible to achieve. The natural world, however, also exhibits structural coloration, where the microstructure of an object causes various colors to appear. Peacock feathers, for instance, are pigmented brown, but — because of long hollows within the feathers — reflect the gorgeous, iridescent blues and greens we see and admire. Recent advances in technology have made it practical to fabricate the kind of nanostructures that result in structural coloration, and computer scientists from the Institute of Science and Technology Austria (IST Austria) and the King Abdullah University of Science and Technology (KAUST) have now created a computational tool that automatically creates 3D-print templates for nanostructures that correspond to user-defined colors. Their work demonstrates the great potential for structural coloring in industry, and opens up possibilities for non-experts to create their own designs. This project will be presented at this year’s top computer graphics conference, SIGGRAPH 2018, by first author and IST Austria postdoc Thomas Auzinger. This is one of five IST Austria presentations at the conference this year.
SIGGRAPH 2018, now ended, was mentioned in my Aug. 9, 2018 posting.but since this presentation is accompanied by a paper, it rates its own posting. For one more excuse, there’s my fascination with structural colour.
The changing colors of a chameleon and the iridescent blues and greens of the morpho butterfly, among many others in nature, are the result of structural coloration, where nanostructures cause interference effects in light, resulting in a variety of colors when viewed macroscopically. Structural coloration has certain advantages over coloring with pigments (where particular wavelengths are absorbed), but until recently, the limits of technology meant fabricating such nanostructures required highly specialized methods. New “direct laser writing” set-ups, however, cost about as much as a high-quality industrial 3D printer, and allow for printing at the scale of hundreds of nanometers (hundred to thousand time thinner than a human hair), opening up possibilities for scientists to experiment with structural coloration.
So far, scientists have primarily experimented with nanostructures that they had observed in nature, or with simple, regular nanostructural designs (e.g. row after row of pillars). Thomas Auzinger and Bernd Bickel of IST Austria, together with Wolfgang Heidrich of KAUST, however, took an innovative new approach that differs in several key ways. First, they solve the inverse design task: the user enters the color they want to replicate, and then the computer creates a nanostructure pattern that gives that color, rather than attempting to reproduce structures found in nature. Moreover, “our design tool is completely automatic,” says Thomas Auzinger. “No extra effort is required on the part of the user.”
Second, the nanostructures in the template do not follow a particular pattern or have a regular structure; they appear to be randomly composed—a radical break from previous methods, but one with many advantages. “When looking at the template produced by the computer I cannot tell by the structure alone, if I see a pattern for blue or red or green,” explains Auzinger. “But that means the computer is finding solutions that we, as humans, could not. This free-form structure is extremely powerful: it allows for greater flexibility and opens up possibilities for additional coloring effects.” For instance, their design tool can be used to print a square that appears red from one angle, and blue from another (known as directional coloring).
Finally, previous efforts have also stumbled when it came to actual fabrication: the designs were often impossible to print. The new design tool, however, guarantees that the user will end up with a printable template, which makes it extremely useful for the future development of structural coloration in industry. “The design tool can be used to prototype new colors and other tools, as well as to find interesting structures that could be produced industrially,” adds Auzinger. Initial tests of the design tool have already yielded successful results. “It’s amazing to see something composed entirely of clear materials appear colored, simply because of structures invisible to the human eye,” says Bernd Bickel, professor at IST Austria, “we’re eager to experiment with additional materials, to expand the range of effects we can achieve.”
“It’s particularly exciting to witness the growing role of computational tools in fabrication,” concludes Auzinger, “and even more exciting to see the expansion of ‘computer graphics’ to encompass physical as well as virtual images.”
The cabbage tree emperor moth (Thomas Neil) [downloaded from https://www.cbc.ca/radio/quirks/nov-17-2018-greenland-asteroid-impact-short-people-in-the-rain-forest-reef-islands-and-sea-level-and-more-1.4906857/how-moths-evolved-a-kind-of-stealth-jet-technology-to-sneak-past-bats-1.4906866]
I don’t think I’ve ever seen a more gorgeous moth and it seems a perfect way to enter 2019, from a November 16, 2018 news item on CBC (Canadian Broadcasting Corporation),
A species of silk moth has evolved special sound absorbing scales on its wings to absorb the sonar pulses from hunting bats. This is analogous to the special coatings on stealth aircraft that allow them to be nearly invisible to radar.
“It’s a battle out there every night, insects flying for their lives trying to avoid becoming a bat’s next dinner,” said Dr. Marc Holderied, the senior author on the paper and an associate professor in the School of Biological Sciences at the University of Bristol.
“If you manage to absorb some of these sound energies, it would make you look smaller and let you be detectable over a shorter distance because echoe isn’t strong enough outside the detection bubble.”
Many moths have ears that warn them when a bat is nearby. But not the big and juicy cabbage tree emperor moths which would ordinarily make the perfect meal for bats.
…
The researchers prepared a brief animated feature illustrating the research,
Prior to publication of the study, the scientists made a presentation at the Acoustical Society of America’s 176th Meeting, held in conjunction with the Canadian Acoustical Association’s 2018 Acoustics Week, Nov. 5-9 at the Victoria Conference Centre in Victoria, Canada according to a November 7, 2018 University of Bristol press release (also on EurekAlert but submitted by the Acoustical Society of America on November 6, 2018),
Moths are a mainstay food source for bats, which use echolocation (biological sonar) to hunt their prey. Scientists such as Thomas Neil, from the University of Bristol in the U.K., are studying how moths have evolved passive defenses over millions of years to resist their primary predators.
While some moths have evolved ears that detect the ultrasonic calls of bats, many types of moths remain deaf. In those moths, Neil has found that the insects developed types of “stealth coating” that serve as acoustic camouflage to evade hungry bats.
Neil will describe his work during the Acoustical Society of America’s 176th Meeting, held in conjunction with the Canadian Acoustical Association’s 2018 Acoustics Week, Nov. 5-9 at the Victoria Conference Centre in Victoria, Canada.
In his presentation, Neil will focus on how fur on a moth’s thorax and wing joints provide acoustic stealth by reducing the echoes of these body parts from bat calls.
“Thoracic fur provides substantial acoustic stealth at all ecologically relevant ultrasonic frequencies,” said Neil, a researcher at Bristol University. “The thorax fur of moths acts as a lightweight porous sound absorber, facilitating acoustic camouflage and offering a significant survival advantage against bats.” Removing the fur from the moth’s thorax increased its detection risk by as much as 38 percent.
Neil used acoustic tomography to quantify echo strength in the spatial and frequency domains of two deaf moth species that are subject to bat predation and two butterfly species that are not.
In comparing the effects of removing thorax fur from insects that serve as food for bats to those that don’t, Neil’s research team found that thoracic fur determines acoustic camouflage of moths but not butterflies.
“We found that the fur on moths was both thicker and denser than that of the butterflies, and these parameters seem to be linked with the absorptive performance of their respective furs,” Neil said. “The thorax fur of the moths was able to absorb up to 85 percent of the impinging sound energy. The maximum absorption we found in butterflies was just 20 percent.”
Neil’s research could contribute to the development of biomimetic materials for ultrathin sound absorbers and other noise-control devices.
“Moth fur is thin and lightweight,” said Neil, “and acts as a broadband and multidirectional ultrasound absorber that is on par with the performance of current porous sound-absorbing foams.”
Moth fur? This has changed my view of moths although I reserve the right to get cranky when local moths chew through my wool sweaters. Here’s a link to and a citation for the paper,
Biomechanics of a moth scale at ultrasonic frequencies by Zhiyuan Shen, Thomas R. Neil, Daniel Robert, Bruce W. Drinkwater, and Marc W. Holderied. PNAS [Proccedings of the National Academy of Sciences of the United States of America] November 27, 2018 115 (48) 12200-12205; published ahead of print November 12, 2018 https://doi.org/10.1073/pnas.1810025115
This paper is behind a paywall.
Unusually I’m going to include the paper’s abstract here,
The wings of moths and butterflies are densely covered in scales that exhibit intricate shapes and sculptured nanostructures. While certain butterfly scales create nanoscale photonic effects [emphasis mine], moth scales show different nanostructures suggesting different functionality. Here we investigate moth-scale vibrodynamics to understand their role in creating acoustic camouflage against bat echolocation, where scales on wings provide ultrasound absorber functionality. For this, individual scales can be considered as building blocks with adapted biomechanical properties at ultrasonic frequencies. The 3D nanostructure of a full Bunaea alcinoe moth forewing scale was characterized using confocal microscopy. Structurally, this scale is double layered and endowed with different perforation rates on the upper and lower laminae, which are interconnected by trabeculae pillars. From these observations a parameterized model of the scale’s nanostructure was formed and its effective elastic stiffness matrix extracted. Macroscale numerical modeling of scale vibrodynamics showed close qualitative and quantitative agreement with scanning laser Doppler vibrometry measurement of this scale’s oscillations, suggesting that the governing biomechanics have been captured accurately. Importantly, this scale of B. alcinoe exhibits its first three resonances in the typical echolocation frequency range of bats, suggesting it has evolved as a resonant absorber. Damping coefficients of the moth-scale resonator and ultrasonic absorption of a scaled wing were estimated using numerical modeling. The calculated absorption coefficient of 0.50 agrees with the published maximum acoustic effect of wing scaling. Understanding scale vibroacoustic behavior helps create macroscopic structures with the capacity for broadband acoustic camouflage.
Those nanoscale photonic effects caused by butterfly scales are something I’d usually describe as optical effects due to the nanoscale structures on some butterfly wings, notably those of the Blue Morpho butterfly. In fact there’s a whole field of study on what’s known as structural colo(u)r. Strictly speaking I’m not sure you could describe the nanostructures on Glasswing butterflies as an example of structure colour since those structures make that butterfly’s wings transparent but they are definitely an optical effect. For the curious, you can use ‘blue morpho butterfly’, ‘glasswing butterfly’ or ‘structural colo(u)r’ to search for more on this blog or pursue bigger fish with an internet search.
