Firefly lanterns inspire efficient LEDs
A published study has revealed that light-emitting diodes inspired by the glow of fireflies can increase light extraction by more than 50 percent.
The more efficient light sources take their inspiration from the jagged scales found inside fireflies, which enhance the glow coming from the creatures. An overlayer mimics the action of the scales and reduces the amount of energy needed by the LED.
“The most important aspect of this work is that it shows how much we can learn by carefully observing nature,” said Annick Bay, a PhD student at the University of Namur in Belgium.
In the fireflies (members of the genus Photuris) a certain amount of light is reflected back into the lantern by the insect’s cuticle — a part of the exoskeleton. But in some fireflies the reflection can be reduced by an arrangement of jagged scales, meaning more light escapes and the firefly appears brighter.
In the LEDs, an overlayer composed of a light-sensitive material which has been lasered into shape mimics the action of these scales, improving efficiency and reducing the energy demand of the light.
“We refer to the edge structures as having a factory roof shape,” says Bay. “The tips of the scales protrude and have a tilted slope, like a factory roof.”
As an added bonus, the efficiency enhancing coating can be applied retrospectively to existing LEDs.
Two studies, published yesterday in Optics Express, describe the shape of scales on the abdomen of fireflies, and an experiment that placed similar structures on LEDs, brightening their output by 55 percent.
Bumblebee Flight Paths Could Inspire Faster Computers
Researchers at Queen Mary University of London have found that bumblebees are capable of complex problem solving that could ultimately lead to faster computer networks and microchips. The researchers discovered that bumblebees find the shortest route among landmarks, in this case flowers, through a simple but effective method.
The researchers set up five fake flowers in a field, each with a little bit of sucrose to entice the bees, and outfitted with motion-triggered web cams. They tracked the bees’ flight paths with tiny bumblebee-mounted radar transponders to see how long it took them to find the fastest route starting from the nest, visiting all five flowers and then back to the nest. The team then modeled the flight paths and found that, amazingly, the bees were able to find the quickest route after trying just 20 out of the 120 possible routes. And the researchers were more surprised that it seemed that the bees were using trial and error, which is a more complex behavior typically seen only in larger-brained animals.
The key, it seems, to their quickly find the shortest route was a simple system where after discovering all five flowers, the bees would start trying new routes. If a new route between flowers was the fastest yet, it would increase the probability that it would be tried again — essentially the bees were committing the fastest routes to memory and eliminating the slower ones until finally an optimal route was found.
Head of Computational and Systems Biology at Rothamsted Research, Professor Chris Rawlings said,”This is an exciting result because it shows that seemingly complex behaviours can be described by relatively simple rules which can be described mathematically.”
The mathematics is what could eventually be used to build faster computer networks, sequence DNA or help delivery companies find the most efficient routes among cities. And just as important, it could help to protect the bumblebees themselves. The researchers found that when a flower was moved or removed, the bees would keep visiting that location for an extended period of time, but then eventually find its new location or a new flower.
“This means we can now use mathematics to inform us when bee behaviour might be affected by their environment and to assess, for example, the impact of changes in the landscape,” Rawlings said.
Self-filling water bottle mimics Namib beetle’s water-trapping wings
A US startup is developing a self-filling water bottle that sucks moisture from the atmosphere to create condensation, in the same way the humble Namib desert beetle does.
The beetle, endemic to Africa’s Namib desert — where there is just 1.3cm of rainfall a year — has inspired a fair few proof-of-concepts in the academic community, but this is the first time a self-filling water bottle has been proposed. The beetle survives by collecting condensation from the ocean breeze on the hardened shell of its wings. The shell is covered in tiny bumps that are water attracting (hydrophilic) at their tips and water-repelling (hydrophobic) at their sides. The beetle extends and aims the wings at incoming sea breezes to catch humid air; tiny droplets 15 to 20 microns in diameter eventually accumulate on its back and run straight down towards its mouth.
NBD Nano, made up of two biologists, an organic chemist and a mechanical engineer, is building on past studies that constructed structurally superior synthetic copies of the shell. An earlier incarnation of the material was first constructed in 2006 by an MIT team — they dipped glass or plastic substrates into solutions of charged polymer chains over and over again to manipulate the surface make-up. Silica nanoparticles were then added to create a rougher, water-trapping texture, and a Teflon-like substance sealed it. Charged polymers and nanoparticles were then layered in patterns to create a contrast between rough and porous surfaces.
NBD Nano says it has achieved proof of concept with its dual water-attracting (superhydrophilic) and water-repelling (superhydrophobic) bottle design, and is currently working on a prototype and seeking funding. Incredibly, the team predicts that the bottle could collect between half a litre and three litres of water per hour, depending on the local environment.
“Dry places like the Atacama Desert or Gobi Desert don’t have access to a lot of sources of water,” cofounder Miguel Galvez told the BBC. “So if we’re creating [several] litres per day in a cost-effective manner, you can get this to a community of people in Sub-Saharan Africa and other dry regions of the world. And if you can do it cheaply enough, then you can really create an impact on the local environment.”
Alan Turing’s Patterns in Nature, and Beyond
Near the end of his life, the great mathematician Alan Turing wrote his first and last paper on biology and chemistry, about how a certain type of chemical reaction ought to produce many patterns seen in nature.
Called “The Chemical Basis of Morphogenesis,” it was an entirely theoretical work. But in following decades, long after Turing tragically took his own life in 1954, scientists found his speculations to be reality.
First found in chemicals in dishes, then in the stripes and spirals and whorls of animals, so-called Turing patterns abounded. Some think that Turing patterns may actually extend to ecosystems, even to galaxies. That’s still speculation — but a proof published Feb. 11 in Science of Turing patterns in a controlled three-dimensional chemical system are even more suggestion of just how complex the patterns can be.
How Turing Patterns Work
At the heart of any Turing pattern is a so-called reaction-diffusion system. It consists of an “activator,” a chemical that can make more of itself; an “inhibitor,” that slows production of the activator; and a mechanism for diffusing the chemicals.
Many combinations of chemicals can fit this system: What matters isn’t their individual identity, but how they interact, with concentrations oscillating between high and low and spreading across an area. These simple units then suffice to produce very complex patterns.
Proving Their Existence
Even though what appeared to be Turing patterns were immediately evident in nature, it wasn’t easy to be sure they were produced by reaction-diffusion systems, rather than some other mechanism.
The breakthrough came during the 1980s, when chemists were able to produce Turing patterns in the laboratory, on thin slabs of gel. In these controlled systems, the reactions could be closely followed, simulated on computers and unambiguously demonstrated as true Turing patterns.
At left in each photograph is a real seashell. At right is a computer-generated image of a pattern produced by a Turing pattern simulation.
At left in each photograph is the eye of a popper fish. At right is a computer-generated image of a pattern generated by a Turing pattern simulation.
Brent Constantz builds cement like corals do
Biomineralization expert Brent Constantz of Stanford University was inspired to make a new type of cement for buildings by the way corals build reefs. The process of making this cement actually removes carbon dioxide – a greenhouse gas, thought to cause global warming – from the air. The company Constantz founded, called Calera, has a demonstration plant on California’s Monterrey Bay. The installation takes waste CO2 gas from a local power plant and dissolves it into seawater to form carbonate, which mixes with calcium in the seawater and creates a solid. It’s how corals form their skeletons, and how Constantz creates cement.
Ray Baughman creates artificial muscles
Nature has been developing her technologies for many hundreds of millions of years, said Ray Baughman. “By looking at the way in which nature has solved problems like muscles, we can advance our own technologies.” Baughman is director of the NanoTech Institute at the University of Texas at Dallas. His lab creates very tiny artificial muscles by spinning filaments of invisibly small carbon nanotubes into an extraordinary yarn. Pound for pound, this nano-yarn is stronger than steel – yet is so light it almost floats in air.
“The thorny devil, a tiny highly specialised lizard from the central Australian desert which lives entirely on ants has each scale enlarged and drawn out to a point in the centre. Few birds could relish such a thorny mouthful and to that extent, they must be a very effective defence, but the shape of the scales also serves another and most unusual function. Each is scored with very thin grooves radiating from the central peak. During cold nights, dew condenses on them and is drawn by capillary action along the grooves and eventually down to the tiny creature’s mouth.” (Attenborough 1979:164)
The Thorny Devil (Moloch horridus) can gather all the water it needs directly from rain, standing water, or from soil moisture, against gravity without using energy or a pumping device. Water is conveyed to this desert lizard’s mouth by capillary action through a circulatory system on the surface of its skin, comprised of semi-enclosed channels 5-150 µm wide running between cutaneous scales. Channel surfaces are heavily convoluted, greatly increasing the effective surface area to which water can hydrogen-bond and hence capillary action force. Passive collection and distribution systems of naturally distilled water could help provide clean water supplies to the 1 billion people estimated to lack this vital resource, reduce the energy consumption required in collecting and transporting water by pump action (e.g., to the tops of buildings), and provide a variety of other inexpensive technological solutions such as managing heat through evaporative cooling systems, protecting structures from fire through on-demand water barriers, etc.
A robot that flies like a bird
Plenty of robots can fly, but none can fly like a real bird. That is, until Markus Fischer and his team at Festo built SmartBird, a large, lightweight robot, modeled on a seagull, that flies by flapping its wings. A soaring demo fresh from TEDGlobal 2011.
This butterfly could hold the secret to letting you see in the dark
The opalescent wings of the Morpho butterfly embody a perfect marriage of aesthetic beauty and biological functionality. Scientists believe that a better understanding of this creature’s wings and their chemical makeup could have big implications for imaging technologies like night vision goggles that rely on sensing heat, rather than visible light.
Now, a team of GE researchers has taken an important step in accomplishing exactly that.
One of the biggest problems facing thermal imaging technologies is temperature management. The sensors in a heat-sensing device have to be cooled constantly, otherwise the image you see becomes washed out with old, and therefore insignificant, heat measurements. Imagine watching a person walk across a room while wearing thermal imaging goggles — if the thermal sensor’s temperature wasn’t kept in check, you’d be able to see a sort of thermal ghost trailing behind the person as they moved across your field of vision.
Physics World’s Tim Wogan explains the challenges of regulating the heat of thermal sensors:
The most sensitive thermal imagers require liquid-helium refrigeration. Since the heat sinks required are relatively large and power-hungry, this limits the minimum size and efficiency of the sensors. These requirements pose severe challenges for those designing portable equipment, such as thermal-imaging goggles. Indeed, goggles pose a particular problem because an ideal pair would be transparent to visible light, which is difficult to achieve with heat sinks in the way.
This is where the Morpho butterfly swoops in to save the day. The scales that cover the Morpho’s iridescent wings reflect light at some wavelengths, while absorbing it at others; these absorption/reflection properties can even change depending on the wings’ temperature, shifting the color of the wings in the process.
This is a pretty inspired biological feature, and it’s one that scientists believe could be put to use in thermal imaging sensors; but what researchers are really impressed with is the chitin that the scales of the Morpho wings are actually made of.
Chitin has a much lower heat capacity than the materials that are used in contemporary thermal sensors; lower heat capacity, in turn, eliminates the need for bulky, energy-hungry cooling methods. In the thermographic video featured here, you can see a Morpho butterfly responding quickly to heat pulses distributed first across the whole butterfly structure, and then onto localized regions of the wings.
And believe it or not, we can make these wings even more impressive — and with carbon nanotubes, no less! Writes Wogan:
Building on previous work by other researchers that revealed that decorating a material surface with carbon nanotubes enhances its ability to absorb infrared radiation, [a research team led by analytical chemist Radislav Potyrailo] showed that the [Morpho’s wings] absorbed infrared better if carbon nanotubes were added to the exposed surface. As a bonus, because carbon nanotubes have excellent thermal conductivity, the decoration helped to diffuse heat through the chitin away from the site of irradiation, thus providing a molecular heat sink.
In other words, Potyrailo and his colleagues showed that treating Morpho scales with carbon nanotubes not only enhances their ability to absorb radiation at wavelengths relevant to thermal imaging, it actually improves their ability to diffuse heat.
The question that remains is: how do researchers translate the functionality of nanotube-doped butterfly wings into a synthetic thermal sensor? Poryrailo and his team have already created an ersatz version of Morpho wings, but they still need a way to incorporate the chitin that grants them their unique heat-dissipating abilities. Once they do that, however, the researchers believe it could mark a major shift toward cheap, more effective thermal-imaging devices.
Better Body Armor? Piranha-Proof Fish Have Answers
The armor that a massive Amazonian fish evolved against piranhas could lead to better body armor for soldiers, researchers say.
The arapaima (Arapaima gigas) is one of the largest freshwater fish in the world, weighing up to 440 pounds (200 kilograms). It lives in the Amazon, and as the waters of the rivers there recede during the dry season, it gets trapped alongside piranhas, and the latter eventually attack every bird, fish, mammal and reptile they can, save alligators.
“I’ve gone to the Amazon many times — I first spent time there as part of a Peace Corps project when I was 20,” said researcher Marc Meyers, a material scientist at the University of California, San Diego. “I remember being struck by how the arapaima could live in these piranha-infested lakes.”
It turns out the arapaima can thrive in this crowded environment. As such, Meyers and his colleagues wanted to learn how it could coexist with such a ravenous predator, especially one with a guillotine-like bite highly effective at slicing through muscle.
The researchers devised a mechanical version of a fight between a piranha and an arapaima. Piranha teeth were attached to what was essentially an industrial-strength hole punch and pressed down onto arapaima scales up to 4 inches (10 centimeters) long, which were embedded on a soft rubber surface that mimicked the muscle of the fish. They found the cutting and puncturing ability of the piranha teeth could not penetrate the arapaima scales.
The arapaima experiments suggest a number of lessons when it comes to designing advanced materials. For instance, the corrugated, ridged surfaces of the scales, which people in the Amazon sometimes use as nail files, help the scales bend without cracking, a discovery that could be of use when working with brittle materials such as ceramics. In addition, the scales mix soft and hard materials — soft collagen fibers stacked in alternating directions like a pile of plywood lend toughness to the scale, and a very hefty mineralized layer on top lends hardness.
Such flexible, tough, hard materials could be useful in body armor, Meyers said. “I believe that this can be used for flexible armor,” he told InnovationNewsDaily. “I am in the process of contacting funding agencies for support.”
The researchers will continue exploring the natural world for inspiration, “asking, ‘how does nature put these things together?’” Meyers said. Another project will involve the alligator gar, a huge fish from the American South whose scales were used by Native Americans as arrow tips. The researchers are also studying abalone shells and leatherback turtle skin for inspiration.
“The materials that nature has at its disposal are not very strong, but nature combines them in a very ingenious way to produce strong components and strong designs,” Meyers said.
The researchers detailed their findings online Jan. 9 in the journal Advanced Engineering Materials. The work was also detailed in the October 2011 issue of the Journal of the Mechanical Behavior of Biomedical Materials.