Researchers at Nagoya University develop a composite material that, by adjusting its composition and exposing it to different types of light, can mimic animals’ changes in color.
Nagoya, Japan – A range of creatures, including chameleons, octopuses, and frogs, can change color in response to changes in the environment. Some insights into the mechanisms behind this at the anatomical, cellular, and molecular levels have been obtained. However, much work is still required to obtain sufficient understanding of this phenomenon and to translate it into useful artificial applications.
As reported in the journal Small, researchers at Nagoya University’s Department of Molecular Design and Engineering developed a material containing dyes and crystals that can change the colors and patterns it displays depending on the background color used within it and its exposure to visible or ultraviolet light.
The team was inspired to develop this material by findings obtained in the skin of certain frogs, in which different layers of cells with different properties combine to enable remarkable color changes.
Biological materials from bonetospider-silk and wood are lightweight fibre composites arranged in a complex hierarchical structure, formed by directed self-assembly to demonstrate outstanding mechanical properties. When such bioinspired stiff and lightweight materials are typically developed for applications in aircraft, automobiles and biomedical implants, their manufacture requires energy and labor-intensive fabrication processes. The manufactured materials also exhibit brittle fracture characteristics with difficulty to shapeandrecycle, in stark contrast to the mechanical properties of nature. Existing polymer-based lightweight structure fabrication is limited to 3-D printing, with poor mechanical strength and orientation, while highly oriented stiff polymers are restricted to construct simple geometries. In an effort to combine the freedom of structural shaping with molecular orientation, 3-D printing of liquid-crystal polymers was recently exploited. Although desirable shape-morphing effects were attained, the Young’s modulus of the soft elastomers were lower than high-performance liquid-crystal synthetic fibers due to their molecular structure.
To fully exploit the shaping freedom of 3-D printing and favorable mechanical properties of molecularly oriented liquid-crystal polymers (LCP), a team of scientists at the Department of Materials, ETH Zürich, proposed a novel approach. The strategy followed two design principles that are used in nature to form tough biological materials. Initially, anisotropy was achieved in the printing process via self-assembly of the LCP ink along the print path. Thereafter, complex-shaping capacity offered by the 3-D printing process was exploited to tailor the local stiffness and strength of the structure based on environmental loading conditions. In the study, Silvan Gantenbein and co-workers demonstrated an approach to generate 3-D lightweight, recyclable structures with hierarchical architecture and complex geometries for unprecedented stiffness and toughness. The results are now published in Nature.
Chameleon-Like Material Spiked With Boron Comes Closer To Mimicking Brain Cells
In a new study, Texas A&M researchers in the Department of Materials Science and Engineering describe a new material that comes close to mimicking how brain cells perform computations.
Each waking moment, our brain processes a massive amount of data to make sense of the outside world. By imitating the way the human brain solves everyday problems, neuromorphic systems have tremendous potential to revolutionize big data analysis and pattern recognition problems that are a struggle for current digital technologies.
But for artificial systems to be more brain-like, they need to replicate how nerve cells communicate at their terminals, called the synapses.
Tesla has revealed its Tesla Semi – an articulated lorry that can travel 500 miles (804km) on a single charge, consuming less than two kilowatt-hours of energy per mile.
With a full 80,000-pound load, the lorry can do 0-60 mph in 20 seconds and can climb 5% gradients at 65mph. The electric vehicle’s battery is reinforced for safety and its windshield is made from impact resistant glass.
According to Chief Executive Elon Musk the Tesla Semi could travel 643km after 30 minutes of charging using one of Tesla’s new mega-chargers. While the lorry’s cost has not yet been revealed, Tesla claims that is will be cheaper than diesel equivalents per mile, considering fuel and maintenance.
The Tesla Semi is due to go into production in 2019.
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A research team led by Dr. Byeong-dae Choi of DGIST’s Intelligent Devices and Systems Research Group has developed an electroluminescent film that is four times brighter than existing ones. The new film can improve the luminance of electroluminescent devices by 422 percent compared to conventional ones by applying retro-reflection electrodes that adapt the principle of nocturnal animal eyes.
Electroluminescent (EL) refers to an optical and electrical phenomenon in which a material emits light in response to the passage of an electric current. Electroluminescent films using phosphor powder have advantages such as excellent durability in a deformed state due to flexibility and elasticity, and high efficiency despite low cost. However, it was difficult to put into practical use due to their low brightness.
In order to increase the brightness of electroluminescent devices, the research team paid attention to the eyes of nocturnal animals with high utilization efficiency of light. The researchers used the retro-reflection characteristics that the light returns to the light source without being dispersed in the retroreflective structure of the nocturnal animal eye while it is scattered in the normal reflection structure.
The complex architecture of bone is challenging to recreate in the lab. Therefore, advances in bone tissue engineering (BTE) aim to build patient-specific grafts that assist bone repair and trigger specific cell-signaling pathways. Materials scientists in regenerative medicine and BTE progressively develop new materials for active biological repair at a site of defect post-implantation to accelerate healing through bone biomimicry.
Rapidly initiation of new bone formation at the site of implantation is a highly desirable feature in BTE, and scientists are focused on fabricating grafts that strengthen the material-bone interface after implantation. Bioactive glass can bond with bone minutes after grafting, and silk fibroin, a natural fibrous protein has potential to induce bone regeneration. Hybrid materials that exploit these properties can combine the osteogenic potential and the load-bearing capacity for potential applications in large-load bone defect models.
In a recent study, Swati Midha and co-workers developed a novel 3-D hybrid construct using silk-based inks with different bioactive glass compositions integrated to recreate a bone-mimetic microenvironment that supports osteogenic differentiation of bone marrow mesenchymal stem cell (BMSC) lines in the lab. Now published in Biomedical Materials, IOP Science, the scientists used direct writing instruments to produce the silk fibroin-gelatin-bioactive glass scaffolds (SF-G-BG). The results delivered appropriate cues to regulate the development of customized 3-D human bone constructs in vitro.
Judging by their name alone, orange puffball sea sponges might seem unlikely paragons of structural strength. But maintaining their shape at the bottom of the churning ocean is critical to the creatures’ survival, and new research shows that tiny structural rods in their bodies have evolved the optimal shape to avoid buckling under pressure.
The rods, called strongyloxea spicules, measure about 2 millimeters long and are thinner than a human hair. Hundreds of them are bundled together, forming stiff rib-like structures inside the orange puffball’s spongy body. It was the odd and remarkably consistent shape of each spicule that caught the eye of Brown University engineers Haneesh Kesari and Michael Monn. Each one is symmetrically tapered along its length – going gradually from fatter in the middle to thinner at the ends.
Using structural mechanics models and a bit of digging in obscure mathematics journals, Monn and Kesari showed the peculiar shape of the spicules to be optimal for resistance to buckling, the primary mode of failure for slender structures. This natural shape could provide a blueprint for increasing the buckling resistance in all kinds of slender human-made structures, from building columns to bicycle spokes to arterial stents, the researchers say.
Studies have shown that hybrid powder materials based on natural layered silicates developed by the chemists of the Far Eastern Federal University (FEFU) and the Far Eastern Branch of the Russian Academy of Sciences (FEB RAS) decrease the friction ratio in metals sevenfold. These new materials offer new prospects for the development of more efficient anti-friction additives, increasing the durability of spare parts for equipment and vehicles.
The work was carried out by research associates of the School of Natural Sciences and Engineering School of FEFU, as well as the Institute of Chemistry of FEB RAS. The research running led by Nikolay Shapkin, professor of the Department of General, Inorganic, and Organoelement chemistry at FEFU. The results were published in Inorganic Materials.
The scientists report two hybrid composite materials based on natural layered silicates and plant products. The first was obtained from nontronite silicate isolated from Popov Island in the vicinity of Vladivostok and modified with alkaline rice husk hydrolysate. Experiments have shown that applying this powder reduces the deterioration of friction-producing parts 2.5 to seven times. Another material based on vermiculite from Karelia and modified with regular cellulose reduced the friction ratio 1.6 times.
Techniques could lead to personalized wearable and implantable devices
Hearing aids, dental crowns, and limb prosthetics are some of the medical devices that can now be digitally designed and customized for individual patients, thanks to 3-D printing. However, these devices are typically designed to replace or support bones and other rigid parts of the body, and are often printed from solid, relatively inflexible material.
Now MIT engineers have designed pliable, 3-D-printed mesh materials whose flexibility and toughness they can tune to emulate and support softer tissues such as muscles and tendons. They can tailor the intricate structures in each mesh, and they envision the tough yet stretchy fabric-like material being used as personalized, wearable supports, including ankle or knee braces, and even implantable devices, such as hernia meshes, that better match to a person’s body.
As a demonstration, the team printed a flexible mesh for use in an ankle brace. They tailored the mesh’s structure to prevent the ankle from turning inward – a common cause of injury – while allowing the joint to move freely in other directions. The researchers also fabricated a knee brace design that could conform to the knee even as it bends. And, they produced a glove with a 3-D-printed mesh sewn into its top surface, which conforms to a wearer’s knuckles, providing resistance against involuntary clenching that can occur following a stroke.
“This work is new in that it focuses on the mechanical properties and geometries required to support soft tissues,” says Sebastian Pattinson, who conducted the research as a postdoc at MIT.
Cuts, scrapes, blisters, burns, splinters, and punctures — there are a number of ways our skin can be broken. Most treatments for skin wounds involve simply covering them with a barrier (usually an adhesive gauze bandage) to keep them moist, limit pain, and reduce exposure to infectious microbes, but they do not actively assist in the healing process.
More sophisticated wound dressings that can monitor aspects of healing such as pH and temperature and deliver therapies to a wound site have been developed in recent years, but they are complex to manufacture, expensive, and difficult to customize, limiting their potential for widespread use.
Now, a new, scalable approach to speeding up wound healing has been developed based on heat-responsive hydrogels that are mechanically active, stretchy, tough, highly adhesive, and antimicrobial: active adhesive dressings (AADs). Created by researchers at the Wyss Institute for Biologically Inspired Engineering at Harvard University, the Harvard John A. Paulson School for Engineering and Applied Sciences (SEAS), and McGill University, AADs can close wounds significantly faster than other methods and prevent bacterial growth without the need for any additional apparatus or stimuli. The research is reported in Science Advances.
Many lessons learned in life are learned from trees. Stand firm. Good things take time. Bend, don’t break. But metaphors aside, our stately arboreal neighbors offer a wealth of scientific wisdom—and we have a lot to learn.
Simply by existing, trees are nature’s first materials scientists. Like many plants, they have vascular systems, networks of tube-like channels that transport water and other vital nutrients from root, to branch, to leaf.
A research team at the Beckman Institute for Advanced Science and Technology developed a chemical process to create foamed polymers with vascular systems of their own, controlling the direction and alignment of the hollow channels to provide structural support and efficiently move fluids through the material.
Their work, “Anisotropic foams via frontal polymerization,” was published in Advanced Materials.
To build more aerodynamic machines, researchers are drawing inspiration from an unlikely source: the ocean.
A team of evolutionary biologists and engineers at Harvard University, in collaboration with colleagues from the University of South Carolina, has shed light on a decades-old mystery about sharkskin and, in the process, demonstrated a new, bioinspired structure that could improve the aerodynamic performance of planes, wind turbines, drones, and cars.
The research is published in the Journal of the Royal Society Interface.
Sharks and airplanes aren’t actually all that different. Both are designed to efficiently move through fluid (water and air), using the shapes of their bodies to generate lift and decrease drag. The difference is, sharks have about a 400-million-year head start on the design process.
“The skin of sharks is covered by thousands and thousands of small scales, or denticles, which vary in shape and size around the body,” said George Lauder, the Henry Bryant Bigelow Professor of Ichthyology and professor of biology in the Department of Organismic and Evolutionary Biology, a co-author of the research. “We know a lot about the structure of these denticles — which are very similar to human teeth — but the function has been debated.”
In nature, colors can serve as a form of communication, but they can also hide animals and plants, camouflaging them from sight. Researchers now report in ACS Applied Materials & Interfaces that they have developed polymers that can better mimic nature’s color-changing abilities than existing polymers. They say the materials could enable smart decorations, camouflage textiles and improved anti-counterfeiting measures.
Most of the colors that people are familiar with, such as hues on a piece of paper, are made with pigments. But another type, called structural color, exists, in which the color is produced by periodically arranged microscopic structures that interfere with visible light. For example, peacock tail feathers are actually brown, but microscopic structures present in the feathers make them look blue and green to the naked eye. Scientists have used cholesteric liquid-crystalline (CLC) polymers to mimic the structural coloration found in nature because they can easily be made into responsive materials. But so far, researchers have only produced them in a limited range of colors. So Albertus P. H. J. Schenning and Monali Moirangthem wanted to make CLC polymers with the full visible spectrum of colors.
For decades, materials scientists have taken inspiration from the natural world. They’ll identify a biological material that has some desirable trait — such as the toughness of bones or conch shells — and reverse-engineer it. Then, once they’ve determined the material’s “microstructure,” they’ll try to approximate it in human-made materials.
Researchers at MIT’s Computer Science and Artificial Intelligence Laboratory have developed a new system that puts the design of microstructures on a much more secure empirical footing. With their system, designers numerically specify the properties they want their materials to have, and the system generates a microstructure that matches the specification.
The researchers have reported their results in Science Advances. In their paper, they describe using the system to produce microstructures with optimal trade-offs between three different mechanical properties. But according to associate professor of electrical engineering and computer science Wojciech Matusik, whose group developed the new system, the researchers’ approach could be adapted to any combination of properties.
“We did it for relatively simple mechanical properties, but you can apply it to more complex mechanical properties, or you could apply it to combinations of thermal, mechanical, optical, and electromagnetic properties,” Matusik says. “Basically, this is a completely automated process for discovering optimal structure families for metamaterials.”
Over hundreds of millions of years of evolution, nature has produced a myriad of biological materials that serve either as skeletons or as defensive or offensive weapons. Although these natural structural materials are derived from relatively sterile natural components, such as fragile minerals and ductile biopolymers, they often exhibit extraordinary mechanical properties due to their highly ordered hierarchical structures and sophisticated interfacial design. Therefore, they are always a research subject for scientists aiming to create advanced artificial structural materials.
Through microstructural observation, researchers have determined that many biological materials, including fish scales, crab claws and bone, all have a characteristic “twisted plywood” structure that consists of a highly ordered arrangement of micro/nanoscale fiber lamellas. They are structurally sophisticated natural fiber-reinforced composites and often exhibit excellent damage tolerance that is desirable for engineering structural materials, but difficult to obtain. Therefore, researchers are seeking to mimic this kind of natural hierarchical structure and interfacial design by using artificial synthetic and abundant one-dimensional micro/nanoscale fibers as building blocks. In this way, they hope to produce high-performance artificial structural materials superior to existing materials. However, due to the lack of micro/nanoscale assembly technology, especially the lack of means to efficiently integrate one-dimensional micro/nanoscale structural units into macroscopic bulk form, mimicking natural fiber-reinforced composites has always been a major challenge.
Screens on even the newest phones and tablets can be hard to read outside in bright sunlight. Inspired by the nanostructures found on moth eyes, researchers have developed a new antireflection film that could keep people from having to run to the shade to look at their mobile devices.
The antireflection film exhibits a surface reflection of just .23 percent, much lower than the iPhone’s surface reflection of 4.4 percent, for example. Reflection is the major reason it’s difficult to read a phone screen in bright sunlight, as the strong light reflecting off the screen’s surface washes out the display.
Researchers led by Shin-Tson Wu of the College of Optics and Photonics, University of Central Florida (CREOL), report on their new antireflection coating in Optica, The Optical Society’s journal for high impact research.
“Using our flexible anti-reflection film on smartphones and tablets will make the screen bright and sharp, even when viewed outside,” said Wu. “In addition to exhibiting low reflection, our nature-inspired film is also scratch resistant and self-cleaning, which would protect touch screens from dust and fingerprints.”
Die ersten drei Bilder (schön herausgeputzt ohne Text) aus unserem geplanten Bioniksachbuch zum Thema “Lotuseffekt”. Hier ist das zweite Set!
Illustration von mir, Ornamentik, Typo und die Icons (Lotuseffekt, Sumpf und Wasser) von Christo Papanouskas.
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These are the first three images of our bookproject about biomimicry. Here is the second set! The illustrations are by me, the ornaments, the typography and the icons (the lotuseffect, swamp and water) are made by my dear friend Christo Papanouskas
