Category Archives: biomimcry

A lobster’s stretch and strength in a hydrogel

An MIT team has fabricated a hydrogel-based material that mimics the structure of the lobster’s underbelly, the toughest known hydrogel found in nature. Credits: Courtesy of the researchers

I love this lobster. In most photos, they’re food. This shows off the lobster as a living entity while showcasing its underbelly, which is what this story is all about. From an April 23, 2021 news item on phys.org (Note: A link has been removed),

A lobster’s underbelly is lined with a thin, translucent membrane that is both stretchy and surprisingly tough. This marine under-armor, as MIT [Massachusetts Institute of Technology] engineers reported in 2019, is made from the toughest known hydrogel in nature, which also happens to be highly flexible. This combination of strength and stretch helps shield a lobster as it scrabbles across the seafloor, while also allowing it to flex back and forth to swim.

Now a separate MIT team has fabricated a hydrogel-based material that mimics the structure of the lobster’s underbelly. The researchers ran the material through a battery of stretch and impact tests, and showed that, similar to the lobster underbelly, the synthetic material is remarkably “fatigue-resistant,” able to withstand repeated stretches and strains without tearing.

If the fabrication process could be significantly scaled up, materials made from nanofibrous hydrogels could be used to make stretchy and strong replacement tissues such as artificial tendons and ligaments.

The team’s results are published in the journal Matter. The paper’s MIT co-authors include postdocs Jiahua Ni and Shaoting Lin; graduate students Xinyue Liu and Yuchen Sun; professor of aeronautics and astronautics Raul Radovitzky; professor of chemistry Keith Nelson; mechanical engineering professor Xuanhe Zhao; and former research scientist David Veysset Ph.D. ’16, now at Stanford University; along with Zhao Qin, assistant professor at Syracuse University, and Alex Hsieh of the Army Research Laboratory.

An April 23, 2021 MIT news release (also on EurekAlert) by Jennifer Chu, which originated the news item, offers an overview of the groundwork for this latest research along with technical detail about the latest work,

Nature’s twist

In 2019, Lin and other members of Zhao’s group developed a new kind of fatigue-resistant material made from hydrogel — a gelatin-like class of materials made primarily of water and cross-linked polymers. They fabricated the material from ultrathin fibers of hydrogel, which aligned like many strands of gathered straw when the material was repeatedly stretched. This workout also happened to increase the hydrogel’s fatigue resistance.

“At that moment, we had a feeling nanofibers in hydrogels were important, and hoped to manipulate the fibril structures so that we could optimize fatigue resistance,” says Lin.

In their new study, the researchers combined a number of techniques to create stronger hydrogel nanofibers. The process starts with electrospinning, a fiber production technique that uses electric charges to draw ultrathin threads out of polymer solutions. The team used high-voltage charges to spin nanofibers from a polymer solution, to form a flat film of nanofibers, each measuring about 800 nanometers — a fraction of the diameter of a human hair.

They placed the film in a high-humidity chamber to weld the individual fibers into a sturdy, interconnected network, and then set the film in an incubator to crystallize the individual nanofibers at high temperatures, further strengthening the material.

They tested the film’s fatigue-resistance by placing it in a machine that stretched it repeatedly over tens of thousands of cycles. They also made notches in some films and observed how the cracks propagated as the films were stretched repeatedly. From these tests, they calculated that the nanofibrous films were 50 times more fatigue-resistant than the conventional nanofibrous hydrogels.

Around this time, they read with interest a study by Ming Guo, associate professor of mechanical engineering at MIT, who characterized the mechanical properties of a lobster’s underbelly. This protective membrane is made from thin sheets of chitin, a natural, fibrous material that is similar in makeup to the group’s hydrogel nanofibers.

Guo found that a cross-section of the lobster membrane revealed sheets of chitin stacked at 36-degree angles, similar to twisted plywood, or a spiral staircase. This rotating, layered configuration, known as a bouligand structure, enhanced the membrane’s properties of stretch and strength.

“We learned that this bouligand structure in the lobster underbelly has high mechanical performance, which motivated us to see if we could reproduce such structures in synthetic materials,” Lin says.

Angled architecture

Ni, Lin, and members of Zhao’s group teamed up with Nelson’s lab and Radovitzky’s group in MIT’s Institute for Soldier Nanotechnologies, and Qin’s lab at Syracuse University, to see if they could reproduce the lobster’s bouligand membrane structure using their synthetic, fatigue-resistant films.

“We prepared aligned nanofibers by electrospinning to mimic the chinic fibers existed in the lobster underbelly,” Ni says.

After electrospinning nanofibrous films, the researchers stacked each of five films in successive, 36-degree angles to form a single bouligand structure, which they then welded and crystallized to fortify the material. The final product measured 9 square centimeters and about 30 to 40 microns thick — about the size of a small piece of Scotch tape.

Stretch tests showed that the lobster-inspired material performed similarly to its natural counterpart, able to stretch repeatedly while resisting tears and cracks — a fatigue-resistance Lin attributes to the structure’s angled architecture.

“Intuitively, once a crack in the material propagates through one layer, it’s impeded by adjacent layers, where fibers are aligned at different angles,” Lin explains.

The team also subjected the material to microballistic impact tests with an experiment designed by Nelson’s group. They imaged the material as they shot it with microparticles at high velocity, and measured the particles’ speed before and after tearing through the material. The difference in velocity gave them a direct measurement of the material’s impact resistance, or the amount of energy it can absorb, which turned out to be a surprisingly tough 40 kilojoules per kilogram. This number is measured in the hydrated state.

“That means that a 5-millimeter steel ball launched at 200 meters per second would be arrested by 13 millimeters of the material,” Veysset says. “It is not as resistant as Kevlar, which would require 1 millimeter, but the material beats Kevlar in many other categories.”

It’s no surprise that the new material isn’t as tough as commercial antiballistic materials. It is, however, significantly sturdier than most other nanofibrous hydrogels such as gelatin and synthetic polymers like PVA. The material is also much stretchier than Kevlar. This combination of stretch and strength suggests that, if their fabrication can be sped up, and more films stacked in bouligand structures, nanofibrous hydrogels may serve as flexible and tough artificial tissues.

“For a hydrogel material to be a load-bearing artificial tissue, both strength and deformability are required,” Lin says. “Our material design could achieve these two properties.”

If you have the time and the interest, do check out the April 23, 2021 MIT news release, which features a couple of informative GIFs.

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

Strong fatigue-resistant nanofibrous hydrogels inspired by lobster underbelly by Jiahua Ni, Shaoting Lin, Zhao Qin, David Veysset, Xinyue Liu, Yuchen Sun, Alex J. Hsieh, Raul Radovitzky, Keith A. Nelson, Xuanhe Zhao. Matter, 2021; DOI: 10.1016/j.matt.2021.03.023 Published April 23, 2021

This paper is behind a paywall.

A new generation of xenobots made with frog cells

I meant to feature this work last year when it was first announced so I’m delighted a second chance has come around so soon after. From a March 31, 2021 news item on ScienceDaily,

Last year, a team of biologists and computer scientists from Tufts University and the University of Vermont (UVM) created novel, tiny self-healing biological machines from frog cells called “Xenobots” that could move around, push a payload, and even exhibit collective behavior in the presence of a swarm of other Xenobots.

Get ready for Xenobots 2.0.

Here’s a video of the Xenobot 2.0. It’s amazing but, for anyone who has problems with animal experimentation, this may be disturbing,


The next version of Xenobots have been created – they’re faster, live longer, and can now record information. (Source: Doug Blackiston & Emma Lederer)

A March 31, 2021 Tufts University news release by Mike Silver (also on EurekAlert and adapted and published as Scientists Create the Next Generation of Living Robots on the University of Vermont website as a UVM Today story),

The same team has now created life forms that self-assemble a body from single cells, do not require muscle cells to move, and even demonstrate the capability of recordable memory. The new generation Xenobots also move faster, navigate different environments, and have longer lifespans than the first edition, and they still have the ability to work together in groups and heal themselves if damaged. The results of the new research were published today [March 31, 2021] in Science Robotics.

Compared to Xenobots 1.0, in which the millimeter-sized automatons were constructed in a “top down” approach by manual placement of tissue and surgical shaping of frog skin and cardiac cells to produce motion, the next version of Xenobots takes a “bottom up” approach. The biologists at Tufts took stem cells from embryos of the African frog Xenopus laevis (hence the name “Xenobots”) and allowed them to self-assemble and grow into spheroids, where some of the cells after a few days differentiated to produce cilia – tiny hair-like projections that move back and forth or rotate in a specific way. Instead of using manually sculpted cardiac cells whose natural rhythmic contractions allowed the original Xenobots to scuttle around, cilia give the new spheroidal bots “legs” to move them rapidly across a surface. In a frog, or human for that matter, cilia would normally be found on mucous surfaces, like in the lungs, to help push out pathogens and other foreign material. On the Xenobots, they are repurposed to provide rapid locomotion. 

“We are witnessing the remarkable plasticity of cellular collectives, which build a rudimentary new ‘body’ that is quite distinct from their default – in this case, a frog – despite having a completely normal genome,” said Michael Levin, Distinguished Professor of Biology and director of the Allen Discovery Center at Tufts University, and corresponding author of the study. “In a frog embryo, cells cooperate to create a tadpole. Here, removed from that context, we see that cells can re-purpose their genetically encoded hardware, like cilia, for new functions such as locomotion. It is amazing that cells can spontaneously take on new roles and create new body plans and behaviors without long periods of evolutionary selection for those features.”

“In a way, the Xenobots are constructed much like a traditional robot.  Only we use cells and tissues rather than artificial components to build the shape and create predictable behavior.” said senior scientist Doug Blackiston, who co-first authored the study with research technician Emma Lederer. “On the biology end, this approach is helping us understand how cells communicate as they interact with one another during development, and how we might better control those interactions.”

While the Tufts scientists created the physical organisms, scientists at UVM were busy running computer simulations that modeled different shapes of the Xenobots to see if they might exhibit different behaviors, both individually and in groups. Using the Deep Green supercomputer cluster at UVM’s Vermont Advanced Computing Core, the team, led by computer scientists and robotics experts Josh Bongard and Sam Kriegman, simulated the Xenbots under hundreds of thousands of random environmental conditions using an evolutionary algorithm.  These simulations were used to identify Xenobots most able to work together in swarms to gather large piles of debris in a field of particles

“We know the task, but it’s not at all obvious — for people — what a successful design should look like. That’s where the supercomputer comes in and searches over the space of all possible Xenobot swarms to find the swarm that does the job best,” says Bongard. “We want Xenobots to do useful work. Right now we’re giving them simple tasks, but ultimately we’re aiming for a new kind of living tool that could, for example, clean up microplastics in the ocean or contaminants in soil.” 

It turns out, the new Xenobots are much faster and better at tasks such as garbage collection than last year’s model, working together in a swarm to sweep through a petri dish and gather larger piles of iron oxide particles. They can also cover large flat surfaces, or travel through narrow capillary tubes.

These studies also suggest that the in silico [computer] simulations could in the future optimize additional features of biological bots for more complex behaviors. One important feature added in the Xenobot upgrade is the ability to record information.

Now with memory

A central feature of robotics is the ability to record memory and use that information to modify the robot’s actions and behavior. With that in mind, the Tufts scientists engineered the Xenobots with a read/write capability to record one bit of information, using a fluorescent reporter protein called EosFP, which normally glows green. However, when exposed to light at 390nm wavelength, the protein emits red light instead. 

The cells of the frog embryos were injected with messenger RNA coding for the EosFP protein before stem cells were excised to create the Xenobots. The mature Xenobots now have a built-in fluorescent switch which can record exposure to blue light around 390nm.
The researchers tested the memory function by allowing 10 Xenobots to swim around a surface on which one spot is illuminated with a beam of 390nm light. After two hours, they found that three bots emitted red light. The rest remained their original green, effectively recording the “travel experience” of the bots.

This proof of principle of molecular memory could be extended in the future to detect and record not only light but also the presence of radioactive contamination, chemical pollutants, drugs, or a disease condition. Further engineering of the memory function could enable the recording of multiple stimuli (more bits of information) or allow the bots to release compounds or change behavior upon sensation of stimuli. 

“When we bring in more capabilities to the bots, we can use the computer simulations to design them with more complex behaviors and the ability to carry out more elaborate tasks,” said Bongard. “We could potentially design them not only to report conditions in their environment but also to modify and repair conditions in their environment.”

Xenobot, heal thyself

“The biological materials we are using have many features we would like to someday implement in the bots – cells can act like sensors, motors for movement, communication and computation networks, and recording devices to store information,” said Levin. “One thing the Xenobots and future versions of biological bots can do that their metal and plastic counterparts have difficulty doing is constructing their own body plan as the cells grow and mature, and then repairing and restoring themselves if they become damaged. Healing is a natural feature of living organisms, and it is preserved in Xenobot biology.” 

The new Xenobots were remarkably adept at healing and would close the majority of a severe full-length laceration half their thickness within 5 minutes of the injury. All injured bots were able to ultimately heal the wound, restore their shape and continue their work as before. 

Another advantage of a biological robot, Levin adds, is metabolism. Unlike metal and plastic robots, the cells in a biological robot can absorb and break down chemicals and work like tiny factories synthesizing and excreting chemicals and proteins. The whole field of synthetic biology – which has largely focused on reprogramming single celled organisms to produce useful molecules – can now be exploited in these multicellular creatures

Like the original Xenobots, the upgraded bots can survive up to ten days on their embryonic energy stores and run their tasks without additional energy sources, but they can also carry on at full speed for many months if kept in a “soup” of nutrients. 

What the scientists are really after

An engaging description of the biological bots and what we can learn from them is presented in a TED talk by Michael Levin. In his TED Talk, professor Levin describes not only the remarkable potential for tiny biological robots to carry out useful tasks in the environment or potentially in therapeutic applications, but he also points out what may be the most valuable benefit of this research – using the bots to understand how individual cells come together, communicate, and specialize to create a larger organism, as they do in nature to create a frog or human. It’s a new model system that can provide a foundation for regenerative medicine.

Xenobots and their successors may also provide insight into how multicellular organisms arose from ancient single celled organisms, and the origins of information processing, decision making and cognition in biological organisms. 

Recognizing the tremendous future for this technology, Tufts University and the University of Vermont have established the Institute for Computer Designed Organisms (ICDO), to be formally launched in the coming months, which will pull together resources from each university and outside sources to create living robots with increasingly sophisticated capabilities.

The ultimate goal for the Tufts and UVM researchers is not only to explore the full scope of biological robots they can make; it is also to understand the relationship between the ‘hardware’ of the genome and the ‘software’ of cellular communications that go into creating organized tissues, organs and limbs. Then we can gain greater control of that morphogenesis for regenerative medicine, and the treatment of cancer and diseases of aging.

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

A cellular platform for the development of synthetic living machines by Douglas Blackiston, Emma Lederer, Sam Kriegman, Simon Garnier, Joshua Bongard, and Michael Levin. Science Robotics 31 Mar 2021: Vol. 6, Issue 52, eabf1571 DOI: 10.1126/scirobotics.abf1571

This paper is behind a paywall.

An electronics-free, soft robotic dragonfly

From the description on YouTube,

With the ability to sense changes in pH, temperature and oil, this completely soft, electronics-free robot dubbed “DraBot” could be the prototype for future environmental sentinels. …

Music: Joneve by Mello C from the Free Music Archive

A favourite motif in the Art Nouveau movement (more about that later in the post), dragonflies or a facsimile thereof feature in March 25, 2021 Duke University news release (also on EurekAlert) by Ken Kingery,

Engineers at Duke University have developed an electronics-free, entirely soft robot shaped like a dragonfly that can skim across water and react to environmental conditions such as pH, temperature or the presence of oil. The proof-of-principle demonstration could be the precursor to more advanced, autonomous, long-range environmental sentinels for monitoring a wide range of potential telltale signs of problems.

The soft robot is described online March 25 [2021] in the journal Advanced Intelligent Systems.

Soft robots are a growing trend in the industry due to their versatility. Soft parts can handle delicate objects such as biological tissues that metal or ceramic components would damage. Soft bodies can help robots float or squeeze into tight spaces where rigid frames would get stuck.

The expanding field was on the mind of Shyni Varghese, professor of biomedical engineering, mechanical engineering and materials science, and orthopaedic surgery at Duke, when inspiration struck.

“I got an email from Shyni from the airport saying she had an idea for a soft robot that uses a self-healing hydrogel that her group has invented in the past to react and move autonomously,” said Vardhman Kumar, a PhD student in Varghese’s laboratory and first author of the paper. “But that was the extent of the email, and I didn’t hear from her again for days. So the idea sort of sat in limbo for a little while until I had enough free time to pursue it, and Shyni said to go for it.”

In 2012, Varghese and her laboratory created a self-healing hydrogel that reacts to changes in pH in a matter of seconds. Whether it be a crack in the hydrogel or two adjoining pieces “painted” with it, a change in acidity causes the hydrogel to form new bonds, which are completely reversible when the pH returns to its original levels.

Varghese’s hastily written idea was to find a way to use this hydrogel on a soft robot that could travel across water and indicate places where the pH changes. Along with a few other innovations to signal changes in its surroundings, she figured her lab could design such a robot as a sort of autonomous environmental sensor.

With the help of Ung Hyun Ko, a postdoctoral fellow also in Varghese’s laboratory, Kumar began designing a soft robot based on a fly. After several iterations, the pair settled on the shape of a dragonfly engineered with a network of interior microchannels that allow it to be controlled with air pressure.

They created the body–about 2.25 inches long with a 1.4-inch wingspan–by pouring silicon into an aluminum mold and baking it. The team used soft lithography to create interior channels and connected with flexible silicon tubing.

DraBot was born.

“Getting DraBot to respond to air pressure controls over long distances using only self-actuators without any electronics was difficult,” said Ko. “That was definitely the most challenging part.”

DraBot works by controlling the air pressure coming into its wings. Microchannels carry the air into the front wings, where it escapes through a series of holes pointed directly into the back wings. If both back wings are down, the airflow is blocked, and DraBot goes nowhere. But if both wings are up, DraBot goes forward.

To add an element of control, the team also designed balloon actuators under each of the back wings close to DraBot’s body. When inflated, the balloons cause the wings to curl upward. By changing which wings are up or down, the researchers tell DraBot where to go.

“We were happy when we were able to control DraBot, but it’s based on living things,” said Kumar. “And living things don’t just move around on their own, they react to their environment.”

That’s where self-healing hydrogel comes in. By painting one set of wings with the hydrogel, the researchers were able to make DraBot responsive to changes in the surrounding water’s pH. If the water becomes acidic, one side’s front wing fuses with the back wing. Instead of traveling in a straight line as instructed, the imbalance causes the robot to spin in a circle. Once the pH returns to a normal level, the hydrogel “un-heals,” the fused wings separate, and DraBot once again becomes fully responsive to commands.

To beef up its environmental awareness, the researchers also leveraged the sponges under the wings and doped the wings with temperature-responsive materials. When DraBot skims over water with oil floating on the surface, the sponges will soak it up and change color to the corresponding color of oil. And when the water becomes overly warm, DraBot’s wings change from red to yellow.

The researchers believe these types of measurements could play an important part in an environmental robotic sensor in the future. Responsiveness to pH can detect freshwater acidification, which is a serious environmental problem affecting several geologically-sensitive regions. The ability to soak up oils makes such long-distance skimming robots an ideal candidate for early detection of oil spills. Changing colors due to temperatures could help spot signs of red tide and the bleaching of coral reefs, which leads to decline in the population of aquatic life.

The team also sees many ways that they could improve on their proof-of-concept. Wireless cameras or solid-state sensors could enhance the capabilities of DraBot. And creating a form of onboard propellant would help similar bots break free of their tubing.

“Instead of using air pressure to control the wings, I could envision using some sort of synthetic biology that generates energy,” said Varghese. “That’s a totally different field than I work in, so we’ll have to have a conversation with some potential collaborators to see what’s possible. But that’s part of the fun of working on an interdisciplinary project like this.”

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

Microengineered Materials with Self‐Healing Features for Soft Robotics by Vardhman Kumar, Ung Hyun Ko, Yilong Zhou, Jiaul Hoque, Gaurav Arya, Shyni Varghese. Advanced Intelligent Systems DOI: https://doi.org/10.1002/aisy.202100005 First published: 25 March 2021

This paper is open access.

The earlier reference to Art Nouveau gives me an excuse to introduce this March 7, 2020 (?) essay by Bex Simon (artist blacksmith) on her eponymous website.

Dragonflies, in particular, are a very poplar subject matter in the Art Nouveau movement. Art Nouveau, with its wonderful flowing lines and hidden fantasies, is full of symbolism.  The movement was a response to the profound social changes and industrialization of every day life and the style of the moment was, in part, inspired by Japanese art.

Simon features examples of Art Nouveau dragonfly art along with examples of her own take on the subject. She also has this,

[downloaded from https://www.bexsimon.com/dragonflies-and-butterflies-in-art-nouveau/]

This is a closeup of a real dragonfly as seen on Simon’s website. If you have an interest, reading her March 7, 2020 (?) essay and gazing at the images won’t take much time.

Submersible dandelions and the materials they could inspire

Before launching into the news item and if you’re as ignorant about the term as I was, here’s what it means to be a dandelion clock, from the dandelion clock definition on Wiktionary [Note: Links have been removed]),

A single stem of a dandelion in its post-flowering state with the downy covering of its head intact. The term is applied when the flower is used, or is thought of as suitable for use, in a children’s pastime by which the number of puffs needed to blow the filamentous achenes from a dandelion is supposed to tell the time.

A March 3, 2021 news item on phys.org announces dandelion research (Note: A link has been removed),

Fields are covered with dandelions in spring, a very common plant with yellow-gold flowers and toothed leaves. When they wither, the flowers turn into fluffy white seed heads that, like tiny parachutes, are scattered around by the wind. Taraxacum officinale—its scientific name—inspired legends and poems and has been used for centuries as a natural remedy for many ailments.

Now, thanks to a study conducted at the University of Trento [Università di Trento], dandelions will inspire new engineered materials. The air trapping capacity of dandelion clocks [emphasis mine] submerged in water has been measured in the lab for the first time. The discovery paves the way for the development of new and advanced devices and technologies that could be used in a broad range of applications, for example, to create devices or materials that retain air bubbles under water.

I found the dandelion squeezing sequence to be quite fascinating.

A March 3, 2021 Università di Trento press release (also on EurekAlert), which originated the news item, provides more detail,

The study was coordinated by Nicola Pugno, professor of the University of Trento and coordinator of the Laboratory of Bio-inspired, Bionic, Nano, Meta Materials & Mechanics at the Department of Civil, Environmental and Mechanical Engineering.
The discovery was given international prominence by “Materials Today Bio”, a multidisciplinary journal focused on the interface between biology and materials science, chemistry, physics, engineering, and medicine.

Nicola Pugno outlined how the research unfolded: “Diego Misseroni and I started to work on a discovery that my daughter made, in her first year in high school. She noticed that dandelion clocks, when submerged by water, turn silvery because they trap air. We have quantified this discovery. For the first time, we have measured the air trapping capacity of dandelion clocks in a laboratory setting. This paper demonstrated that kids and young adults can make significant discoveries by observing nature”.

When submerged in water, the research team observed, the soft seed heads turn silver in color, become thinner and take on a rhombus-like shape. The team then developed an analytical model to measure the mechanical properties of the flower, in order to mimic them and create re-engineered dandelion-like materials.

Bioinspired engineering can explore different opportunities thanks to this discovery, such as miniaturized parachute-like elements to develop innovative devices and advanced, light and low-cost technological solutions to trap and transport air bubbles underwater. These materials could be used, for example, in underwater operations.

It’s been a while (see my Nov. 21, 2018 posting ‘Regenerating tooth enamel’) since I’ve featured research from Nicola Pugno here.

Here’s a link to and a citation for Pugno’s dandelion-ispired work

Air-encapsulating elastic mechanism of submerged Taraxacum blowballs by M.C.Pugno, D.Misseroni, N.M.Pugno. Materials Today Bio Volume 9, January 2021, 100095 DOI: 10.1016/j.mtbio.2021.100095

This paper is open access.

A 3D spider web, a VR (virtual reality) setup, and sonification (music)

Markus Buehler and his musical spider webs are making news again.

Caption: Cross-sectional images (shown in different colors) of a spider web were combined into this 3D image and translated into music. Credit: Isabelle Su and Markus Buehler

The image (so pretty) you see in the above comes from a Markus Buehler presentation that was made at the American Chemical Society (ACS) meeting. ACS Spring 2021 being held online April 5-30, 2021. The image was also shown during a press conference which the ACS has made available for public viewing. More about that later in this posting.

The ACS issued an April 12, 2021 news release (also on EurekAlert), which provides details about Buehler’s latest work on spider webs and music,

Spiders are master builders, expertly weaving strands of silk into intricate 3D webs that serve as the spider’s home and hunting ground. If humans could enter the spider’s world, they could learn about web construction, arachnid behavior and more. Today, scientists report that they have translated the structure of a web into music, which could have applications ranging from better 3D printers to cross-species communication and otherworldly musical compositions.

The researchers will present their results today at the spring meeting of the American Chemical Society (ACS). ACS Spring 2021 is being held online April 5-30 [2021]. Live sessions will be hosted April 5-16, and on-demand and networking content will continue through April 30 [2021]. The meeting features nearly 9,000 presentations on a wide range of science topics.

“The spider lives in an environment of vibrating strings,” says Markus Buehler, Ph.D., the project’s principal investigator, who is presenting the work. “They don’t see very well, so they sense their world through vibrations, which have different frequencies.” Such vibrations occur, for example, when the spider stretches a silk strand during construction, or when the wind or a trapped fly moves the web.

Buehler, who has long been interested in music, wondered if he could extract rhythms and melodies of non-human origin from natural materials, such as spider webs. “Webs could be a new source for musical inspiration that is very different from the usual human experience,” he says. In addition, by experiencing a web through hearing as well as vision, Buehler and colleagues at the Massachusetts Institute of Technology (MIT), together with collaborator Tomás Saraceno at Studio Tomás Saraceno, hoped to gain new insights into the 3D architecture and construction of webs.

With these goals in mind, the researchers scanned a natural spider web with a laser to capture 2D cross-sections and then used computer algorithms to reconstruct the web’s 3D network. The team assigned different frequencies of sound to strands of the web, creating “notes” that they combined in patterns based on the web’s 3D structure to generate melodies. The researchers then created a harp-like instrument and played the spider web music in several live performances around the world.

The team also made a virtual reality setup that allowed people to visually and audibly “enter” the web. “The virtual reality environment is really intriguing because your ears are going to pick up structural features that you might see but not immediately recognize,” Buehler says. “By hearing it and seeing it at the same time, you can really start to understand the environment the spider lives in.”

To gain insights into how spiders build webs, the researchers scanned a web during the construction process, transforming each stage into music with different sounds. “The sounds our harp-like instrument makes change during the process, reflecting the way the spider builds the web,” Buehler says. “So, we can explore the temporal sequence of how the web is being constructed in audible form.” This step-by-step knowledge of how a spider builds a web could help in devising “spider-mimicking” 3D printers that build complex microelectronics. “The spider’s way of ‘printing’ the web is remarkable because no support material is used, as is often needed in current 3D printing methods,” he says.

In other experiments, the researchers explored how the sound of a web changes as it’s exposed to different mechanical forces, such as stretching. “In the virtual reality environment, we can begin to pull the web apart, and when we do that, the tension of the strings and the sound they produce change. At some point, the strands break, and they make a snapping sound,” Buehler says.

The team is also interested in learning how to communicate with spiders in their own language. They recorded web vibrations produced when spiders performed different activities, such as building a web, communicating with other spiders or sending courtship signals. Although the frequencies sounded similar to the human ear, a machine learning algorithm correctly classified the sounds into the different activities. “Now we’re trying to generate synthetic signals to basically speak the language of the spider,” Buehler says. “If we expose them to certain patterns of rhythms or vibrations, can we affect what they do, and can we begin to communicate with them? Those are really exciting ideas.”

You can go here for the April 12, 2021 ‘Making music from spider webs’ ACS press conference’ it runs about 30 mins. and you will hear some ‘spider music’ played.

Getting back to the image and spider webs in general, we are most familiar with orb webs (in the part of Canada where I from if nowhere else), which look like spirals and are 2D. There are several other types of webs some of which are 3D, like tangle webs, also known as cobwebs, funnel webs and more. See this March 18, 2020 article “9 Types of Spider Webs: Identification + Pictures & Spiders” by Zach David on Beyond the Treat for more about spiders and their webs. If you have the time, I recommend reading it.

I’ve been following Buehler’s spider web/music work for close to ten years now; the latest previous posting is an October 23, 2019 posting where you’ll find a link to an application that makes music from proteins (spider webs are made up of proteins; scroll down about 30% of the way; it’s in the 2nd to last line of the quoted text about the embedded video).

Here is a video (2 mins. 17 secs.) of a spider web music performance that Buehler placed on YouTube,

Feb 3, 2021

Markus J. Buehler

Spider’s Canvas/Arachonodrone show excerpt at Palais de Tokyo, Paris, on November 2018. Video by MIT CAST. More videos can be found on www.arachnodrone.com. The performance was commissioned by Studio Tomás Saraceno (STS), in the context of Saraceno’s carte blanche exhibition, ON AIR. Spider’s Canvas/Arachnodrone was performed by Isabelle Su and Ian Hattwick on the spider web instrument, Evan Ziporyn on the EWI (Electronic Wind Instrument), and Christine Southworth on the guitar and EBow (Electronic Bow)

You can find more about the spider web music and Buehler’s collaborators on http://www.arachnodrone.com/,

Spider’s Canvas / Arachnodrone is inspired by the multifaceted work of artist Tomas Saraceno, specifically his work using multiple species of spiders to make sculptural webs. Different species make very different types of webs, ranging not just in size but in design and functionality. Tomas’ own web sculptures are in essence collaborations with the spiders themselves, placing them sequentially over time in the same space, so that the complex, 3-dimensional sculptural web that results is in fact built by several spiders, working together.

Meanwhile, back among the humans at MIT, Isabelle Su, a Course 1 doctoral student in civil engineering, has been focusing on analyzing the structure of single-species spider webs, specifically the ‘tent webs’ of the cyrtophora citricola, a tropical spider of particular interest to her, Tomas, and Professor Markus Buehler. Tomas gave the department a cyrtophora spider, the department gave the spider a space (a small terrarium without glass), and she in turn built a beautiful and complex web. Isabelle then scanned it in 3D and made a virtual model. At the suggestion of Evan Ziporyn and Eran Egozy, she then ported the model into Unity, a VR/game making program, where a ‘player’ can move through it in numerous ways. Evan & Christine Southworth then worked with her on ‘sonifying’ the web and turning it into an interactive virtual instrument, effectively turning the web into a 1700-string resonating instrument, based on the proportional length of each individual piece of silk and their proximity to one another. As we move through the web (currently just with a computer trackpad, but eventually in a VR environment), we create a ‘sonic biome’: complex ‘just intonation’ chords that come in and out of earshot according to which of her strings we are closest to. That part was all done in MAX/MSP, a very flexible high level audio programming environment, which was connected with the virtual environment in Unity. Our new colleague Ian Hattwick joined the team focusing on sound design and spatialization, building an interface that allowed him the sonically ‘sculpt’ the sculpture in real time, changing amplitude, resonance, and other factors. During this performance at Palais de Tokyo, Isabelle toured the web – that’s what the viewer sees – while Ian adjusted sounds, so in essence they were together “playing the web.” Isabelle provides a space (the virtual web) and a specific location within it (by driving through), which is what the viewer sees, from multiple angles, on the 3 scrims. The location has certain acoustic potentialities, and Ian occupies them sonically, just as a real human performer does in a real acoustic space. A rough analogy might be something like wandering through a gothic cathedral or a resonant cave, using your voice or an instrument at different volumes and on different pitches to find sonorous resonances, echoes, etc. Meanwhile, Evan and Christine are improvising with the web instrument, building on Ian’s sound, with Evan on EWI (Electronic Wind Instrument) and Christine on electric guitar with EBow.

For the visuals, Southworth wanted to create the illusion that the performers were actually inside the web. We built a structure covered in sharkstooth scrim, with 3 projectors projecting in and through from 3 sides. Southworth created images using her photographs of local Lexington, MA spider webs mixed with slides of the scan of the web at MIT, and then mixed those images with the projection of the game, creating an interactive replica of Saraceno’s multi-species webs.

If you listen to the press conference, you will hear Buehler talk about practical applications for this work in materials science.

Lobster-inspired 3D printed concrete

A January 19, 2021 news item on ScienceDaily highlights bioinspired 3D printing of concrete,

New research shows that patterns inspired by lobster shells can make 3D printed concrete stronger, to support more complex and creative architectural structures.

Digital manufacturing technologies like 3D concrete printing (3DCP) have immense potential to save time, effort and material in construction.

They also promise to push the boundaries of architectural innovation, yet technical challenges remain in making 3D printed concrete strong enough for use in more free-form structures.

In a new experimental study, researchers at RMIT University [Australia] looked to the natural strength of lobster shells to design special 3D printing patterns.

Their bio-mimicking spiral patterns improved the overall durability of the 3D printed concrete, as well as enabling the strength to be precisely directed for structural support where needed.

Video: Carelle Mulawa-Richards

A January 19, 2021 RMIT University press release (also on EurekAlert) by Gosia Kaszubska, which originated the news item, goes into technical detail about the research once you get past the ‘fluffy’ bits,

When the team combined the twisting patterns with a specialised concrete mix enhanced with steel fibres, the resulting material was stronger than traditionally-made concrete.

Lead researcher Dr Jonathan Tran said 3D printing and additive manufacturing opened up opportunities in construction for boosting both efficiency and creativity.

“3D concrete printing technology has real potential to revolutionise the construction industry, and our aim is to bring that transformation closer,” said Tran, a senior lecturer in structured materials and design at RMIT.

“Our study explores how different printing patterns affect the structural integrity of 3D printed concrete, and for the first time reveals the benefits of a bio-inspired approach in 3DCP.

“We know that natural materials like lobster exoskeletons?have evolved into high-performance structures over millions of years, so by mimicking their key advantages we can follow where nature has already innovated.”

3D printing for construction

The automation of concrete construction is set to transform how we build, with construction the next frontier in the automation and data-driven revolution known as industry 4.0.

A 3D concrete printer builds houses or makes structural components by depositing the material layer-by-layer, unlike the traditional approach of casting concrete in a mould.

With the latest technology, a house can be 3D printed in just 24 hours for about half the cost, while construction on the world’s first 3D printed community began in 2019 in Mexico.

The emerging industry is already supporting architectural and engineering innovation, such as a 3D printed office building in Dubai, a nature-mimicking concrete bridge in Madrid and The Netherlands’ sail-shaped “Europe Building”.

The research team in RMIT’s School of Engineering focuses on 3D printing concrete, exploring ways to enhance the finished product through different combinations of printing pattern design, material choices, modelling, design optimisation and reinforcement options.

Patterns for printing

The most conventional pattern used in 3D printing is unidirectional, where layers are laid down on top of each other in parallel lines.

The new study published in a special issue of 3D Printing and Additive Manufacturing investigated the effect of different printing patterns on the strength of steel fibre-enhanced concrete.

Previous research by the RMIT team found that including 1-2% steel fibres in the concrete mix reduces defects and porosity, increasing strength. The fibres also help the concrete harden early without deformation, enabling higher structures to be built.

The team tested the impact of printing the concrete in helicoidal patterns (inspired by the internal structure of lobster shells), cross-ply and quasi-isotropic patterns (similar to those used for laminated composite structures and layer-by-layer deposited composites) and standard unidirectional patterns.

Supporting complex structures

The results showed strength improvement from each of the patterns, compared with unidirectional printing, but Tran said the spiral patterns hold the most promise for supporting complex 3D printed concrete structures.

“As lobster shells are naturally strong and naturally curved, we know this could help us deliver stronger concrete shapes like arches and flowing or twisted structures,” he said.

“This work is in early stages so we need further research to test how the concrete performs on a wider range of parameters, but our initial experimental results show we are on the right track.”

Further studies will be supported through a new large-scale mobile concrete 3D printer recently acquired by RMIT – making it the first research institution in the southern hemisphere to commission a machine of this kind.

The 5×5m robotic printer will be used by the team to research the 3D printing of houses, buildings and large structural components.

The team will also use the machine to explore the potential for 3D printing with concrete made with recycled waste materials such as soft plastic aggregate.

The work is connected to a new project with industry partners Replas and SR Engineering, focusing on sound-dampening walls made from post-consumer recycled soft plastics and concrete, which was recently supported with an Australian Government Innovations Connections grant.

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

Influences of Printing Pattern on Mechanical Performance of Three-Dimensional-Printed Fiber-Reinforced Concrete by Luong Pham, Guoxing Lu, and Phuong Tran. 3D Printing and Additive Manufacturing DOI: https://doi.org/10.1089/3dp.2020.0172 Published Online:30 Dec 2020

This paper is open access.

A lotus root-inspired hydrogel fiber for surgical sutures

By FotoosRobin – originally posted to Flickr as Lotus root, CC BY-SA 2.0, https://commons.wikimedia.org/w/index.php?curid=4826529

The lotus (Nelumbo nucifera) rhizome (mass of roots) is not the prettiest part of the lotus but its fibers (and presumably fiber from other parts of the lotus plant) served as inspiration for a hydrogel that might be used as a surgical suture according to a Jan. 14, 2021 news item on phys.org (Note: Links have been removed),

“The lotus roots may break, but the fiber remains joined”—an old Chinese saying that reflects the unique structure and mechanical properties of the lotus fiber. The outstanding mechanical properties of lotus fibers can be attributed to their unique spiral structure, which provides an attractive model for biomimetic design of artificial fibers.

In a new study published in Nano Letters, a team led by Prof. Yu Shuhong from the University of Science and Technology of China (USTC) of the Chinese Academy of Sciences (CAS) reported a bio-inspired lotus-fiber-mimetic spiral structure bacterial cellulose (BC) hydrogel fiber with high strength, high toughness, excellent biocompatibility, good stretchability, and high energy dissipation.

A Jan. 14, 2021 University of Science and Technology of China press release on the Chinese Academy of Sciences website (also on EurekAlert), which originated the news item, describes the new hydrogel in more detail,

Unlike polymer-based hydrogel, the newly designed biomimetic hydrogel fiber (BHF) is based on the BC hydrogel with 3D cellulose nanofiber networks produced by bacteria. The cellulose nanofibers provide the reversible hydrogen bonding network that results in unique mechanical properties.

The researchers applied a constant tangential force to the pretreated BC hydrogel along the cross-sectional direction. Then, the two sides of the hydrogel were subjected to opposite tangential forces, and local plastic deformation occurred.

The hydrogen bonds in the 3D network of cellulose nanofibers were broken by the tangential force, causing the hydrogel strip to twist spirally and the network to slip and deform. When the tangential force was removed, the hydrogen bonds reformed between the nanofibers, and the spiral structure of the fiber was fixed.

Benefited from lotus-fiber-mimetic spiral structure, the toughness of BHF can reach ?116.3 MJ m-3, which is more than nine times higher than those of non-spiralized BC hydrogel fiber. Besides, once the BHF is stretched, it is nearly non-resilient.

Combining outstanding mechanical properties with excellent biocompatibility derived from BC, BHF is a promising hydrogel fiber for biomedical material, especially for surgical suture, a commonly used structural biomedical material for wound repair.

Compared with commercial surgical suture with higher modulus, the BHF has similar modulus and strength to soft tissue, like skin. The outstanding stretchability and energy dissipation of BHF allow it to absorb energy from the tissue deformation around a wound and effectively protect the wound from rupture, which makes BHF an ideal surgical suture.

What’s more, the porous structure of BHF also allows it to adsorb functional small molecules, such as antibiotics or anti-inflammatory compounds, and sustainably release them on wounds. With an appropriate design, BHF would be a powerful platform for many medical applications.

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

Bio-Inspired Lotus-Fiber-like Spiral Hydrogel Bacterial Cellulose Fibers by Qing-Fang Guan, Zi-Meng Han, YinBo Zhu, Wen-Long Xu, Huai-Bin Yang, Zhang-Chi Ling, Bei-Bei Yan, Kun-Peng Yang, Chong-Han Yin, HengAn Wu, and Shu-Hong Yu. Nano Lett. 2021, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acs.nanolett.0c03707 Publication Date:January 5, 2021 Copyright © 2021 American Chemical Society

This paper is behind a paywall.

Mother-of-pearl self-assembles from disorder into perfection

Courtesy: Mother-of-pearl Courtesy: Technische Universitaet (TU) Dresden

Mother-of-pearl (also known as nacre) research has been featured here a few times (links at the end of this post). This time it touches on self-assembly, which is the source of much interest and, on occasion, much concern in the field of nanotechnology.

In any case, the latest mother-of-pearl work comes from the Technische Universität (TU) Dresden (Technical University of Dresden), located in Germany. From a January 4, 2021 news item on phys.org,

In a new study published in Nature Physics, researchers from the B CUBE—Center for Molecular Bioengineering at TU Dresden and European Synchrotron Radiation Facility (ESRF) in Grenoble [Grance] describe, for the first time, that structural defects in self-assembling nacre attract and cancel each other out, eventually leading to a perfect periodic structure.

A January 4, 2021 Technische Universität (TU) Dresden press release (also on EurekAlert), which originated the news item, explains the reason for the ongoing interest in mother-of-pearl and reveals an unexpected turn in the research,

Mollusks build shells to protect their soft tissues from predators. Nacre, also known as the mother of pearl, has an intricate, highly regular structure that makes it an incredibly strong material. Depending on the species, nacres can reach tens of centimeters in length. No matter the size, each nacre is built from materials deposited by a multitude of single cells at multiple different locations at the same time. How exactly this highly periodic and uniform structure emerges from the initial disorder was unknown until now.

Nacre formation starts uncoordinated with the cells depositing the material simultaneously at different locations. Not surprisingly, the early nacre structure is not very regular. At this point, it is full of defects. “In the very beginning, the layered mineral-organic tissue is full of structural faults that propagate through a number of layers like a helix. In fact, they look like a spiral staircase, having either right-handed or left-handed orientation,” says Dr. Igor Zlotnikov, research group leader at the B CUBE – Center for Molecular Bioengineering at TU Dresden. “The role of these defects in forming such a periodic tissue has never been established. On the other hand, the mature nacre is defect-free, with a regular, uniform structure. How could perfection emerge from such disorder?”

The researchers from the Zlotnikov group collaborated with the European Synchrotron Radiation Facility (ESRF) in Grenoble to take a very detailed look at the internal structure of the early and mature nacre. Using synchrotron-based holographic X-ray nano-tomography the researchers could capture the growth of nacre over time. “Nacre is an extremely fine structure, having organic features below 50 nm in size. Beamline ID16A at the ESRF provided us with an unprecedented capability to visualize nacre in three-dimensions,” explains Dr. Zlotnikov. “The combination of electron dense and highly periodical inorganic platelets with delicate and slender organic interfaces makes nacre a challenging structure to image. Cryogenic imaging helped us to obtain the resolving power we needed,” explains Dr. ‘Alexandra] Pacureanu from the X-ray Nanoprobe group at the ESRF.

The analysis of data was quite a challenge. The researchers developed a segmentation algorithm using neural networks and trained it to separate different layers of nacre. In this way, they were able to follow what happens to the structural defects as nacre grows.

The behavior of structural defects in a growing nacre was surprising. Defects of opposite screw direction were attracted to each other from vast distances. The right-handed and left-handed defects moved through the structure, until they met, and cancelled each other out. These events led to a tissue-wide synchronization. Over time, it allowed the structure to develop into a perfectly regular and defect-free.

Periodic structures similar to nacre are produced by many different animal species. The researchers think that the newly discovered mechanism could drive not only the formation of nacre but also other biogenic structures.

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

Dynamics of topological defects and structural synchronization in a forming periodic tissue by Maksim Beliaev, Dana Zöllner, Alexandra Pacureanu, Paul Zaslansky & Igor Zlotnikov. Nature Physics (2021) First published online: 17 September 2020 Published: 04 January 2021

This paper is behind a paywall.

As promised here are the links for One tough mother, imitating mother-of-pearl for stronger ceramics (a March 14, 2014 posting) and Clues as to how mother of pearl is made (a December 15, 2015 posting).

Water and minerals have a nanoscale effect on bones

Courtesy: University of Arkansas

What a great image of bones! This December 3, 2020 University of Arkansas news release (also on EurekAlert) by Matt McGowan features research focused on bone material looks exciting. The date for the second study citation and link that I have listed (at the end of this posting) suggests the more recent study may have been initially overlooked in the deluge of COVID-19 research we are experiencing,

University of Arkansas researchers Marco Fielder and Arun Nair have conducted the first study of the combined nanoscale effects of water and mineral content on the deformation mechanisms and thermal properties of collagen, the essence of bone material.

The researchers also compared the results to the same properties of non-mineralized collagen reinforced with carbon nanotubes, which have shown promise as a reinforcing material for bio-composites. This research aids in the development of synthetic materials to mimic bone.

Using molecular dynamics — in this case a computer simulation of the physical movements of atoms and molecules — Nair and Fielder examined the mechanics and thermal properties of collagen-based bio-composites containing different weight percentages of minerals, water and carbon nanotubes when subjected to external loads.

They found that variations of water and mineral content had a strong impact on the mechanical behavior and properties of the bio-composites, the structure of which mimics nanoscale bone composition. With increased hydration, the bio-composites became more vulnerable to stress. Additionally, Nair and Fielder found that the presence of carbon nanotubes in non-mineralized collagen reduced the deformation of the gap regions.

The researchers also tested stiffness, which is the standard measurement of a material’s resistance to deformation. Both mineralized and non-mineralized collagen bio-composites demonstrated less stability with greater water content. Composites with 40% mineralization were twice as strong as those without minerals, regardless of the amount of water content. Stiffness of composites with carbon nanotubes was comparable to that of the mineralized collagen.

“As the degree of mineralization or carbon nanotube content of the collagenous bio-composites increased, the effect of water to change the magnitude of deformation decreased,” Fielder said.

The bio-composites made of collagen and carbon nanotubes were also found to have a higher specific heat than the studied mineralized collagen bio-composites, making them more likely to be resistant to thermal damage that could occur during implantation or functional use of the composite. Like most biological materials, bone is a hierarchical – with different structures at different length scales. At the microscale level, bone is made of collagen fibers, composed of smaller nanofibers called fibrils, which are a composite of collagen proteins, mineralized crystals called apatite and water. Collagen fibrils overlap each other in some areas and are separated by gaps in other areas.

“Though several studies have characterized the mechanics of fibrils, the effects of variation and distribution of water and mineral content in fibril gap and overlap regions are unexplored,” said Nair, who is an associate professor of mechanical engineering. “Exploring these regions builds an understanding of the structure of bone, which is important for uncovering its material properties. If we understand these properties, we can design and build better bio-inspired materials and bio-composites.”

Here are links and citations for both papers mentioned in the news release,

Effects of hydration and mineralization on the deformation mechanisms of collagen fibrils in bone at the nanoscale by Marco Fielder & Arun K. Nair. Biomechanics and Modeling in Mechanobiology volume 18, pages57–68 (2019) Biomech Model Mechanobiol 18, 57–68 (2019). DOI: https://doi.org/10.1007/s10237-018-1067-y First published: 07 August 2018 Issue Date: 15 February 2019

This paper is behind a paywall.

A computational study of mechanical properties of collagen-based bio-composites by Marco Fielder & Arun K. Nair. International Biomechanics Volume 7, 2020 – Issue 1 Pages 76-87 DOI: https://doi.org/10.1080/23335432.2020.1812428 Published online: 02 Sep 2020

This paper is open access.

Spider web-like electronics with graphene

A spiderweb-inspired fractal design is used for hemispherical 3D photodetection to replicate the vision system of arthropods. (Sena Huh image)

This image is pretty and I’m pretty sure it’s an illustration and not a real photodetection system. Regardless, an Oct. 21, 2020 news item on Nanowerk describes the research into producing a real 3D hemispheric photodetector for biomedical imaging (Note: A link has been removed),

Purdue University innovators are taking cues from nature to develop 3D photodetectors for biomedical imaging.

The researchers used some architectural features from spider webs to develop the technology. Spider webs typically provide excellent mechanical adaptability and damage-tolerance against various mechanical loads such as storms.

“We employed the unique fractal design of a spider web for the development of deformable and reliable electronics that can seamlessly interface with any 3D curvilinear surface,” said Chi Hwan Lee, a Purdue assistant professor of biomedical engineering and mechanical engineering. “For example, we demonstrated a hemispherical, or dome-shaped, photodetector array that can detect both direction and intensity of incident light at the same time, like the vision system of arthropods such as insects and crustaceans.”

The Purdue technology uses the structural architecture of a spider web that exhibits a repeating pattern. This work is published in Advanced Materials (“Fractal Web Design of a Hemispherical Photodetector Array with Organic-Dye-Sensitized Graphene Hybrid Composites”).

An Oct. 21, 2020 Purdue University news release by Chris Adam, which originated the news item, delves further into the work,

Lee said this provides unique capabilities to distribute externally induced stress throughout the threads according to the effective ratio of spiral and radial dimensions and provides greater extensibility to better dissipate force under stretching. Lee said it also can tolerate minor cuts of the threads while maintaining overall strength and function of the entire web architecture.

“The resulting 3D optoelectronic architectures are particularly attractive for photodetection systems that require a large field of view and wide-angle antireflection, which will be useful for many biomedical and military imaging purposes,” said Muhammad Ashraful Alam, the Jai N. Gupta Professor of Electrical and Computer Engineering.

Alam said the work establishes a platform technology that can integrate a fractal web design with system-level hemispherical electronics and sensors, thereby offering several excellent mechanical adaptability and damage-tolerance against various mechanical loads.

“The assembly technique presented in this work enables deploying 2D deformable electronics in 3D architectures, which may foreshadow new opportunities to better advance the field of 3D electronic and optoelectronic devices,” Lee said.

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

Fractal Web Design of a Hemispherical Photodetector Array with Organic‐Dye‐Sensitized Graphene Hybrid Composites by Eun Kwang Lee, Ratul Kumar Baruah, Jung Woo Leem, Woohyun Park, Bong Hoon Kim, Augustine Urbas, Zahyun Ku, Young L. Kim, Muhammad Ashraful Alam, Chi Hwan Lee. Advanced Materials Volume 32, Issue 46 November 19, 2020 2004456 DOI: https://doi.org/10.1002/adma.202004456 First published online: 12 October 2020

This paper is behind a paywall.