Tag Archives: Argonne National Laboratory (ANL)

Neuromorphic (brainlike) computing inspired by sea slugs

The sea slug has taught neuroscientists the intelligence features that any creature in the animal kingdom needs to survive. Now, the sea slug is teaching artificial intelligence how to use those strategies. Pictured: Aplysia californica. (Image by NOAA Monterey Bay National Marine Sanctuary/Chad King.)

I don’t think I’ve ever seen a picture of a sea slug before. Its appearance reminds me of its terrestrial cousin.

As for some of the latest news on brainlike computing, a December 7, 2021 news item on Nanowerk makes an announcement from the Argonne National Laboratory (a US Department of Energy laboratory; Note: Links have been removed),

A team of scientists has discovered a new material that points the way toward more efficient artificial intelligence hardware for everything from self-driving cars to surgical robots.

For artificial intelligence (AI) to get any smarter, it needs first to be as intelligent as one of the simplest creatures in the animal kingdom: the sea slug.

A new study has found that a material can mimic the sea slug’s most essential intelligence features. The discovery is a step toward building hardware that could help make AI more efficient and reliable for technology ranging from self-driving cars and surgical robots to social media algorithms.

The study, published in the Proceedings of the National Academy of Sciences [PNAS] (“Neuromorphic learning with Mott insulator NiO”), was conducted by a team of researchers from Purdue University, Rutgers University, the University of Georgia and the U.S. Department of Energy’s (DOE) Argonne National Laboratory. The team used the resources of the Advanced Photon Source (APS), a DOE Office of Science user facility at Argonne.

A December 6, 2021 Argonne National Laboratory news release (also on EurekAlert) by Kayla Wiles and Andre Salles, which originated the news item, provides more detail,

“Through studying sea slugs, neuroscientists discovered the hallmarks of intelligence that are fundamental to any organism’s survival,” said Shriram Ramanathan, a Purdue professor of Materials Engineering. ​“We want to take advantage of that mature intelligence in animals to accelerate the development of AI.”

Two main signs of intelligence that neuroscientists have learned from sea slugs are habituation and sensitization. Habituation is getting used to a stimulus over time, such as tuning out noises when driving the same route to work every day. Sensitization is the opposite — it’s reacting strongly to a new stimulus, like avoiding bad food from a restaurant.

AI has a really hard time learning and storing new information without overwriting information it has already learned and stored, a problem that researchers studying brain-inspired computing call the ​“stability-plasticity dilemma.” Habituation would allow AI to ​“forget” unneeded information (achieving more stability) while sensitization could help with retaining new and important information (enabling plasticity).

In this study, the researchers found a way to demonstrate both habituation and sensitization in nickel oxide, a quantum material. Quantum materials are engineered to take advantage of features available only at nature’s smallest scales, and useful for information processing. If a quantum material could reliably mimic these forms of learning, then it may be possible to build AI directly into hardware. And if AI could operate both through hardware and software, it might be able to perform more complex tasks using less energy.

“We basically emulated experiments done on sea slugs in quantum materials toward understanding how these materials can be of interest for AI,” Ramanathan said.

Neuroscience studies have shown that the sea slug demonstrates habituation when it stops withdrawing its gill as much in response to tapping. But an electric shock to its tail causes its gill to withdraw much more dramatically, showing sensitization.

For nickel oxide, the equivalent of a ​“gill withdrawal” is an increased change in electrical resistance. The researchers found that repeatedly exposing the material to hydrogen gas causes nickel oxide’s change in electrical resistance to decrease over time, but introducing a new stimulus like ozone greatly increases the change in electrical resistance.

Ramanathan and his colleagues used two experimental stations at the APS to test this theory, using X-ray absorption spectroscopy. A sample of nickel oxide was exposed to hydrogen and oxygen, and the ultrabright X-rays of the APS were used to see changes in the material at the atomic level over time.

“Nickel oxide is a relatively simple material,” said Argonne physicist Hua Zhou, a co-author on the paper who worked with the team at beamline 33-ID. ​“The goal was to use something easy to manufacture, and see if it would mimic this behavior. We looked at whether the material gained or lost a single electron after exposure to the gas.”

The research team also conducted scans at beamline 29-ID, which uses softer X-rays to probe different energy ranges. While the harder X-rays of 33-ID are more sensitive to the ​“core” electrons, those closer to the nucleus of the nickel oxide’s atoms, the softer X-rays can more readily observe the electrons on the outer shell. These are the electrons that define whether a material is conductive or resistive to electricity.

“We’re very sensitive to the change of resistivity in these samples,” said Argonne physicist Fanny Rodolakis, a co-author on the paper who led the work at beamline 29-ID. ​“We can directly probe how the electronic states of oxygen and nickel evolve under different treatments.”

Physicist Zhan Zhang and postdoctoral researcher Hui Cao, both of Argonne, contributed to the work, and are listed as co-authors on the paper. Zhang said the APS is well suited for research like this, due to its bright beam that can be tuned over different energy ranges.

For practical use of quantum materials as AI hardware, researchers will need to figure out how to apply habituation and sensitization in large-scale systems. They also would have to determine how a material could respond to stimuli while integrated into a computer chip.

This study is a starting place for guiding those next steps, the researchers said. Meanwhile, the APS is undergoing a massive upgrade that will not only increase the brightness of its beams by up to 500 times, but will allow for those beams to be focused much smaller than they are today. And this, Zhou said, will prove useful once this technology does find its way into electronic devices.

“If we want to test the properties of microelectronics,” he said, ​“the smaller beam that the upgraded APS will give us will be essential.”

In addition to the experiments performed at Purdue and Argonne, a team at Rutgers University performed detailed theory calculations to understand what was happening within nickel oxide at a microscopic level to mimic the sea slug’s intelligence features. The University of Georgia measured conductivity to further analyze the material’s behavior.

A version of this story was originally published by Purdue University

About the Advanced Photon Source

The U. S. Department of Energy Office of Science’s Advanced Photon Source (APS) at Argonne National Laboratory is one of the world’s most productive X-ray light source facilities. The APS provides high-brightness X-ray beams to a diverse community of researchers in materials science, chemistry, condensed matter physics, the life and environmental sciences, and applied research. These X-rays are ideally suited for explorations of materials and biological structures; elemental distribution; chemical, magnetic, electronic states; and a wide range of technologically important engineering systems from batteries to fuel injector sprays, all of which are the foundations of our nation’s economic, technological, and physical well-being. Each year, more than 5,000 researchers use the APS to produce over 2,000 publications detailing impactful discoveries, and solve more vital biological protein structures than users of any other X-ray light source research facility. APS scientists and engineers innovate technology that is at the heart of advancing accelerator and light-source operations. This includes the insertion devices that produce extreme-brightness X-rays prized by researchers, lenses that focus the X-rays down to a few nanometers, instrumentation that maximizes the way the X-rays interact with samples being studied, and software that gathers and manages the massive quantity of data resulting from discovery research at the APS.

This research used resources of the Advanced Photon Source, a U.S. DOE Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No. DE-AC02-06CH11357.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation’s first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America’s scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy’s Office of Science.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://​ener​gy​.gov/​s​c​ience.

You can find the September 24, 2021 Purdue University story, Taking lessons from a sea slug, study points to better hardware for artificial intelligence here.

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

Neuromorphic learning with Mott insulator NiO by Zhen Zhang, Sandip Mondal, Subhasish Mandal, Jason M. Allred, Neda Alsadat Aghamiri, Alireza Fali, Zhan Zhang, Hua Zhou, Hui Cao, Fanny Rodolakis, Jessica L. McChesney, Qi Wang, Yifei Sun, Yohannes Abate, Kaushik Roy, Karin M. Rabe, and Shriram Ramanathan. PNAS September 28, 2021 118 (39) e2017239118 DOI: https://doi.org/10.1073/pnas.2017239118

This paper is behind a paywall.

Technology for mopping up oil spills

It’s a little disheartening to write about technology for mopping up oils spills as there doesn’t to be much improvement in the situation as Adele Peters notes in her June 4, 2021 article (A decade after Deepwater Horizon, we’re still cleaning up oil spills the same way) for Fast Company (Note: Links have been removed),

Off the coastline of Sri Lanka, where a burning cargo ship has been spilling toxic chemicals and plastic pellets over the past two weeks, the government is preparing for the next possible stage of the disaster: As the ship sinks, it may also spill some of the hundreds of tons of oil in its fuel tanks.

The government is readying oil dispersants, booms, and oil skimmers, all tools that were used in the massive Deepwater Horizon oil spill in the Gulf of Mexico in 2010. They didn’t work perfectly then—more than 1,000 miles of shoreline were polluted—and more than a decade later, they’re still commonly used. But solutions that might work better are under development, including reusable sponges that can suck up oil both on the surface and underwater.

Dispersants, one common tool now, are chemicals designed to break up the oil into tiny droplets so that, in theory, microorganisms in the water can break down the oil more easily. But at least one study found that dispersant could harm those organisms. Deep-sea coral also appears to suffer more from the mix of dispersant and oil than oil alone. Booms are designed to contain oil on the surface so it can be scraped off with a skimmer, but that only works if the water’s relatively calm, and it doesn’t deal with oil below the surface. The oil on the surface can also be burned, but it creates a plume of thick black smoke. “That does get rid of the oil from the water, but then it turns a water pollution problem into an air pollution problem,” says Seth Darling, a senior scientist at Argonne National Laboratory who developed an alternative called the Oleo Sponge [emphasis mine].

… a team from two German universities that developed a system of wood chips that can be dropped in the water to collect oil even in rough weather, when current tools don’t work well. The system is ready for deployment if a spill happens in the Baltic Sea. Another earlier-stage solution proposes using a robot to detect and capture oil.

I’m glad to see at least one new oil spill cleanup technology being readied for deployment in Peters’ June 4, 2021 article, we should be preparing for more spills as the Arctic melts and plans are made to develop new shipping routes.

Amongst other oil spill cleanup technologies, Peters mentions the ‘Oleo Sponge’, which was featured here in a March 30, 2017 posting when researchers were looking for investors to commercialize the product. According to Peters the oleo sponge hasn’t yet made it to market; it’s a fate many of these technologies are destined to meet. Meanwhile, scientists continue to develop new methods and techniques for mopping up oil spills as safely as possible. For example, there’s an oil spill sucking robot mentioned in my October 30, 2020 posting, which features yet another article by Peters.

In the summer of 2020 there were two major oil spills, one in the Russian Arctic and one in an ecologically sensitive area near Mauritius. For more about those events, there’s an August 14, 2020 posting, which starts with news of an oil spill technology featuring dog fur and then focuses primarily on the oil spill in the Russian Arctic with a brief mention of the spill near Mauritius in June 2020 (scroll down to the ‘Exceptionally warm weather’ subhead and see the paragraph above it for the mention and a link to a story).

‘Nanotraps’ for catching and destroying coronavirus

‘Nanotraps’ are not vaccines although they do call the immune system into play. They represent a different way for dealing with COVID-19. (This work reminds of my June 24, 2020 posting Tiny sponges lure coronavirus away from lung cells where the researchers have a similar approach with what they call ‘nanosponges’.)

An April 27, 2021 news item on Nanowerk makes the announcement,

Researchers at the Pritzker School of Molecular Engineering (PME) at the University of Chicago have designed a completely novel potential treatment for COVID-19: nanoparticles that capture SARS-CoV-2 viruses within the body and then use the body’s own immune system to destroy it.

These “Nanotraps” attract the virus by mimicking the target cells the virus infects. When the virus binds to the Nanotraps, the traps then sequester the virus from other cells and target it for destruction by the immune system.

In theory, these Nanotraps could also be used on variants of the virus, leading to a potential new way to inhibit the virus going forward. Though the therapy remains in early stages of testing, the researchers envision it could be administered via a nasal spray as a treatment for COVID-19.

A scanning electron microscope image of a nanotrap (orange) binding a simulated SARS-CoV-2 virus (dots in green). Scientists at the University of Chicago created these nanoparticles as a potential treatment for COVID-19. Image courtesy Chen and Rosenberg et al.

An April 27, 2021 University of Chicago news release (also on EurekAlert) by Emily Ayshford, which originated the news item, describes the work in more detail,

“Since the pandemic began, our research team has been developing this new way to treat COVID-19,” said Asst. Prof. Jun Huang, whose lab led the research. “We have done rigorous testing to prove that these Nanotraps work, and we are excited about their potential.”

Designing the perfect trap

To design the Nanotrap, the research team – led by postdoctoral scholar Min Chen and graduate student Jill Rosenberg – looked into the mechanism SARS-CoV-2 uses to bind to cells: a spike-like protein on its surface that binds to a human cell’s ACE2 receptor protein.

To create a trap that would bind to the virus in the same way, they designed nanoparticles with a high density of ACE2 proteins on their surface. Similarly, they designed other nanoparticles with neutralizing antibodies on their surfaces. (These antibodies are created inside the body when someone is infected and are designed to latch onto the coronavirus in various ways).

Both ACE2 proteins and neutralizing antibodies have been used in treatments for COVID-19, but by attaching them to nanoparticles, the researchers created an even more robust system for trapping and eliminating the virus.

Made of FDA [US Food and Drug Administration]-approved polymers and phospholipids, the nanoparticles are about 500 nanometers in diameter – much smaller than a cell. That means the Nanotraps can reach more areas inside the body and more effectively trap the virus.

The researchers tested the safety of the system in a mouse model and found no toxicity. They then tested the Nanotraps against a pseudovirus – a less potent model of a virus that doesn’t replicate – in human lung cells in tissue culture plates and found that they completely blocked entry into the cells.

Once the pseudovirus bound itself to the nanoparticle – which in tests took about 10 minutes after injection – the nanoparticles used a molecule that calls the body’s macrophages to engulf and degrade the Nanotrap. Macrophages will generally eat nanoparticles within the body, but the Nanotrap molecule speeds up the process. The nanoparticles were cleared and degraded within 48 hours.

The researchers also tested the nanoparticles with a pseudovirus in an ex vivo lung perfusion system – a pair of donated lungs that is kept alive with a ventilator – and found that they completely blocked infection in the lungs.

They also collaborated with researchers at Argonne National Laboratory to test the Nanotraps with a live virus (rather than a pseudovirus) in an in vitro system. They found that their system inhibited the virus 10 times better than neutralizing antibodies or soluble ACE2 alone.

A potential future treatment for COVID-19 and beyond

Next the researchers hope to further test the system, including more tests with a live virus and on the many virus variants.

“That’s what is so powerful about this Nanotrap,” Rosenberg said. “It’s easily modulated. We can switch out different antibodies or proteins or target different immune cells, based on what we need with new variants.”

The Nanotraps can be stored in a standard freezer and could ultimately be given via an intranasal spray, which would place them directly in the respiratory system and make them most effective.

The researchers say it is also possible to serve as a vaccine by optimizing the Nanotrap formulation, creating an ultimate therapeutic system for the virus.

“This is the starting point,” Huang said. “We want to do something to help the world.”

The research involved collaborators across departments, including chemistry, biology, and medicine.

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

Nanotraps for the containment and clearance of SARS-CoV-2 by Min Chen, Jillian Rosenberg, Xiaolei Cai, Andy Chao Hsuan Lee, Jiuyun Shi, Mindy Nguyen, Thirushan Wignakumar, Vikranth Mirle, Arianna Joy Edobor, John Fung, Jessica Scott Donington, Kumaran Shanmugarajah, Yiliang Lin, Eugene Chang, Glenn Randall, Pablo Penaloza-MacMaster, Bozhi Tian, Maria Lucia Madariaga, Jun Huang. Matter, April 19, 2021, DOI: https://doi.org/10.1016/j.matt.2021.04.005

This paper appears to be open access.

Alloy nanoparticles make better catalysts

A Jan. 4, 2021 news item on Nanowerk describes new insights into nanoscale catalysts derived from work at the US Argonne National Laboratory,

Catalysts are integral to countless aspects of modern society. By speeding up important chemical reactions, catalysts support industrial manufacturing and reduce harmful emissions. They also increase efficiency in chemical processes for applications ranging from batteries and transportation to beer and laundry detergent.

As significant as catalysts are, the way they work is often a mystery to scientists. Understanding catalytic processes can help scientists develop more efficient and cost-effective catalysts. In a recent study, scientists from University of Illinois Chicago (UIC) and the U.S. Department of Energy’s (DOE) Argonne National Laboratory discovered that, during a chemical reaction that often quickly degrades catalytic materials, a certain type of catalyst displays exceptionally high stability and durability.

The catalysts in this study are alloy nanoparticles, or nanosized particles made up of multiple metallic elements, such as cobalt, nickel, copper and platinum. These nanoparticles could have multiple practical applications, including water-splitting to generate hydrogen in fuel cells; reduction of carbon dioxide by capturing and converting it into useful materials like methanol; more efficient reactions in biosensors to detect substances in the body; and solar cells that produce heat, electricity and fuel more effectively.

A January 4, 2021 Argonne National Laboratory news release (also on EurekAlert) by Savannah Mitchem fills in some details,

In this study, the scientists investigated “high-entropy” (highly stable) alloy nanoparticles. The team of researchers, led by Reza Shahbazian-Yassar at UIC, used Argonne’s Center for Nanoscale Materials (CNM), a DOE Office of Science user facility, to characterize the particles’ compositions during oxidation, a process that degrades the material and reduces its usefulness in catalytic reactions.

“Using gas flow transmission electron microscopy (TEM) at CNM, we can capture the whole oxidation process in real time and at very high resolution,” said scientist Bob Song from UIC, a lead scientist on the study. “We found that the high-entropy alloy nanoparticles are able to resist oxidation much better than general metal particles.”

To perform the TEM, the scientists embedded the nanoparticles into a silicon nitride membrane and flowed different types of gas through a channel over the particles. A beam of electrons probed the reactions between the particles and the gas, revealing the low rate of oxidation and the migration of certain metals — iron, cobalt, nickel and copper — to the particles’ surfaces during the process.

“Our objective was to understand how fast high-entropy materials react with oxygen and how the chemistry of nanoparticles evolves during such a reaction,” said Shahbazian-Yassar, UIC professor of mechanical and industrial engineering at the College of Engineering.

According to Shahbazian-Yassar, the discoveries made in this research could benefit many energy storage and conversion technologies, such as fuel cells, lithium-air batteries, supercapacitors and catalyst materials. The nanoparticles could also be used to develop corrosion-resistant and high-temperature materials.

“This was a successful showcase of how CNM’s capabilities and services can meet the needs of our collaborators,” said Argonne’s Yuzi Liu, a scientist at CNM. “We have state-of-the-art facilities, and we want to deliver state-of-the-art science as well.”

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

In Situ Oxidation Studies of High-Entropy Alloy Nanoparticles by Boao Song, Yong Yang, Muztoba Rabbani, Timothy T. Yang, Kun He, Xiaobing Hu, Yifei Yuan, Pankaj Ghildiyal, Vinayak P. Dravid, Michael R. Zachariah, Wissam A. Saidi, Yuzi Liu, and Reza Shahbazian-Yassar. ACS Nano 2020, 14, 11, 15131–15143 DOI: https://doi.org/10.1021/acsnano.0c05250 Publication Date:October 20, 2020 Copyright © 2020 American Chemical Society

This paper is behind a paywall.

Below is one of my favourite types of video work, a ‘blob video’ from the University of Illinois showing the alloy nanoparticles as they oxidate,

Video of transmission electron microscopy, performed at Argonne’s CNM, showing the oxidation of high-entropy nanoparticles in air at 400 °C, sped up by a factor of four. The oxidation process is depicted by the dissolution of the edges of the nanoparticles in the video. (Image by University of Illinois.)

Ferroelectric roadmap to neuromorphic computing

Having written about memristors and neuromorphic engineering a number of times here, I’m  quite intrigued to see some research into another nanoscale device for mimicking the functions of a human brain.

The announcement about the latest research from the team at the US Department of Energy’s Argonne National Laboratory is in a Feb. 14, 2017 news item on Nanowerk (Note: A link has been removed),

Research published in Nature Scientific Reports (“Ferroelectric symmetry-protected multibit memory cell”) lays out a theoretical map to use ferroelectric material to process information using multivalued logic – a leap beyond the simple ones and zeroes that make up our current computing systems that could let us process information much more efficiently.

A Feb. 10, 2017 Argonne National Laboratory news release by Louise Lerner, which originated the news item, expands on the theme,

The language of computers is written in just two symbols – ones and zeroes, meaning yes or no. But a world of richer possibilities awaits us if we could expand to three or more values, so that the same physical switch could encode much more information.

“Most importantly, this novel logic unit will enable information processing using not only “yes” and “no”, but also “either yes or no” or “maybe” operations,” said Valerii Vinokur, a materials scientist and Distinguished Fellow at the U.S. Department of Energy’s Argonne National Laboratory and the corresponding author on the paper, along with Laurent Baudry with the Lille University of Science and Technology and Igor Lukyanchuk with the University of Picardie Jules Verne.

This is the way our brains operate, and they’re something on the order of a million times more efficient than the best computers we’ve ever managed to build – while consuming orders of magnitude less energy.

“Our brains process so much more information, but if our synapses were built like our current computers are, the brain would not just boil but evaporate from the energy they use,” Vinokur said.

While the advantages of this type of computing, called multivalued logic, have long been known, the problem is that we haven’t discovered a material system that could implement it. Right now, transistors can only operate as “on” or “off,” so this new system would have to find a new way to consistently maintain more states – as well as be easy to read and write and, ideally, to work at room temperature.

Hence Vinokur and the team’s interest in ferroelectrics, a class of materials whose polarization can be controlled with electric fields. As ferroelectrics physically change shape when the polarization changes, they’re very useful in sensors and other devices, such as medical ultrasound machines. Scientists are very interested in tapping these properties for computer memory and other applications; but the theory behind their behavior is very much still emerging.

The new paper lays out a recipe by which we could tap the properties of very thin films of a particular class of ferroelectric material called perovskites.

According to the calculations, perovskite films could hold two, three, or even four polarization positions that are energetically stable – “so they could ‘click’ into place, and thus provide a stable platform for encoding information,” Vinokur said.

The team calculated these stable configurations and how to manipulate the polarization to move it between stable positions using electric fields, Vinokur said.

“When we realize this in a device, it will enormously increase the efficiency of memory units and processors,” Vinokur said. “This offers a significant step towards realization of so-called neuromorphic computing, which strives to model the human brain.”

Vinokur said the team is working with experimentalists to apply the principles to create a working system

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

Ferroelectric symmetry-protected multibit memory cell by Laurent Baudry, Igor Lukyanchuk, & Valerii M. Vinokur. Scientific Reports 7, Article number: 42196 (2017) doi:10.1038/srep42196 Published online: 08 February 2017

This paper is open access.

X-ray of a butterfly’s wing reveals structural colour secrets

Over millions of years, butterflies evolved sophisticated cellular mechanisms to produce brightly colored wings for mating and camouflage. iStock photo by Borut Trdina

Over millions of years, butterflies evolved sophisticated cellular mechanisms to produce brightly colored wings for mating and camouflage. iStock photo by Borut Trdina

A June 13, 2016 news item on Nanowerk announced a discovery about the physics of colour,

A team of physicists that visualized the internal nanostructure of an intact butterfly wing has discovered two physical attributes that make those structures so bright and colorful.

“Over millions of years, butterflies have evolved sophisticated cellular mechanisms to grow brightly colored structures, normally for the purpose of camouflage as well as mating,” says Oleg Shpyrko, an associate professor of physics at UC San Diego, who headed the research effort. “It’s been known for a century that the wings of these beautiful creatures contain what are called photonic crystals, which can reflect light of only a particular color.”

But exactly how these complex optical structures are assembled in a way that make them so bright and colorful remained a mystery.

A June 10, 2016 University of California at San Diego news release (also on EurekAlert), which originated the news item, describes how the mystery was solved,

In an effort to answer that question, Shpyrko and Andrej Singer, a postdoctoral researcher in his laboratory, went to the Advanced Photon Source at the Argonne National Laboratory in Illinois, which produces coherent x-rays very much like an optical laser

By combining these laser-like x-rays with an advanced imaging technique called “ptychography,” the UC San Diego physicists, in collaboration with physicists at Yale University and the Argonne National Laboratory, developed a new microscopy method to visualize the internal nanostructure of the tiny “scales” that make up the butterfly wing without the need to cut them apart.

The researchers report in the current issue of the journal Science Advances that their examination of the scales of the Emperor of India butterfly, Teinopalpus imperialis, revealed that these tiny wing structures consist of “highly oriented” photonic crystals.

“This explains why the scales appear to have a single color,” says Singer, the first author of the paper. “We also found through careful study of the high-resolution micrographs tiny crystal irregularities that may enhance light-scattering properties, making the butterfly wings appear brighter.”

These crystal dislocations or defects occur, the researchers say, when an otherwise perfectly periodic crystal lattice slips by one row of atoms. “Defects may have a negative connotation, but they are actually very useful in improving materials,” explains Singer. “For example, blacksmiths have learned over centuries how to purposefully induce defects into metals to make them stronger. ‘Defect engineering’ is also a focus for many research teams and companies working in the semiconductor field. In photonic crystals, defects can enhance light-scattering properties through an effect called light localization.”

“In the evolution of butterfly wings,” he adds, “it appears nature learned how to engineer these defects on purpose.”

The researchers have made this image illustrating their work available,

Scales from the wings of the Emperor of India butterfly consist of “highly oriented” photonic crystals. Photos by Andrej Singer, UC San Diego

Scales from the wings of the Emperor of India butterfly consist of “highly oriented” photonic crystals. Photos by Andrej Singer, UC San Diego

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

Domain morphology, boundaries, and topological defects in biophotonic gyroid nanostructures of butterfly wing scales by Andrej Singer, Leandra Boucheron, Sebastian H. Dietze, Katharine E. Jensen, David Vine, Ian McNulty, Eric R. Dufresne, Richard O. Prum, Simon G. J. Mochrie, and Oleg G. Shpyrko. Science Advances  10 Jun 2016: Vol. 2, no. 6, e1600149 DOI: 10.1126/sciadv.1600149

This paper is open access.