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Sierra Daily

02/04/2013

5 Nature-Inspired Innovations

GeckoTokayUAThe shifting hues of squid skin, the stickiness of gecko toes, the self-cleansing of lotus leaves. Understanding these and other natural phenomena can yield not only fascinating biological insights, but also fresh solutions to today’s most pressing environmental challenges. Biomimicry — applying the design of natural systems to human problems — has gained momentum in recent years. Last August, the San Diego Zoo opened its Center for Bioinspiration, which works with companies and research institutions to translate zoo scientists’ findings into practical applications. Taking cues from nature makes sense. Plants and animals have a 3.8 billion year head start on scientists in adapting to natural pressures, whether that involves using sunlight efficiently or keeping cool in hot, arid climates. Here’s a look at five biomimicry advances that emerged within the past year.

1.) Cleaner wind turbines and solar panels: Eastern religions revere the lotus plant as a symbol of purity. Indeed, its broad leaves float unsoiled atop the muddy, marshy water from which the plant grows. It turns out that the microscopic bumps on the leaf's surface cause water droplets to form and roll off, pulling dirt along with them. This water-repelling mechanism has inspired coatings for solar panels to keep them cleaner. The dirt and dust that solar panels collect over time could make them work less efficiently. Researchers have created similar coatings to keep ice from forming on wind turbine blades. Last April, researchers at the Massachusetts Institute of Technology drew inspiration from the lotus leaf to develop a surface texture on glass that lacks reflection and causes water droplets to bounce right off. A solar panel shielded by this new surface (whose design also draws from moth eyes and beetle carapaces) would work more efficiently not only because it’s cleaner, but also because it can transmit more light. The MIT researchers say that the surfaces they’ve developed are more effective at repelling water than waterproof coatings from earlier work. Click below to watch a video of the glare-free, waterproof glass in action:  

 

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2.) Energy-efficient e-readers: The delicate skin of cephalopods — the class of marine animals that includes octopuses, squid, and cuttlefish — can change color in less than seconds to hide the animals from predators or communicate an array of signals, from warnings to mating cues. In a review published last September, scientists at the University of Cincinnati examined how color change in these sea chameleons can help improve the e-paper technology behind the Kindle and similar devices with screens that can be read under sunlight. The most effective color changing approaches use pigment, modulating color by spreading or compacting that pigment. Animals do this by contracting and relaxing muscle fibers, while electronics generate an electric field. Still, scientists have much to learn from cephalopods. Though electronics can display and change colors faster than biological organisms, they need to produce a large amount of electric power to emanate bright colors. In contrast, a cephalopod’s skin can create brilliant displays without generating light on its own. Scientists and engineers may be able to translate the tentacled creatures’ color capabilities into e-reader experiences that are visually stunning but still use light efficiently.    

3.) Brighter LEDs Scientists from Belgium, France, and Canada have developed a coating that could make the light-emitting diodes, or LEDs, used in everyday lighting more efficient. The coating's design gives a nod to the pattern of scales on a firefly’s lantern, the organ located on its abdomen that flashes to allure mates. Firefly panel 2A firefly's light results from a chemical reaction that occurs in the cuticle, a part of the insect's protective outer covering. Light moves through the cuticle slower than it does through air, causing light to reflect back into the lantern and shine less brightly. But a certain arrangement of rough, misfit scales on some fireflies' cuticles allows more light to filter through. In the lab, researchers noticed that the “factory roof-shaped” edges of those scales transmitted the most light compared to other cuticle structures. The left panel of the photo shows a firefly specimen from the genus Photuris, which is commonly found in Latin America and the United States and served as the inspiration for the effective new LED coating. The right panel shows the misfit scales found on the lantern of the Photuris firefly. OpEx - firefly LEDs - image3

"The tips of the scales protrude and have a tilted slope, like a factory roof,” Annick Bay, a Ph.D. student at Belgium’s University of Namur, who co-authored the two papers describing the technology, explained in a press release. LEDs and fireflies' lanterns both have a problem with overcoming internal reflection. Following their hunch that factory roof-shaped coating could offer a solution, Bay and other research team members coated a gallium nitride (GaN) LED with light-sensitive material laser-etched with the “factory-roof” pattern. They observed that the coating increased light extraction by 55 percent. What’s more, the coating can easily be applied to existing LEDs, which means that manufacturing new, specially coated LEDs from scratch may not be necessary. At right is a photo of a GaN LED, coated with a “factory-roof” pattern modeled after the fireflies’ scales.

 

 

Gecko foot 

4.) Reusable adhesives: Geckos are renowned for their astonishing wall-crawling abilities, their feet able to cling over and over again to the trickiest of surfaces, even moist areas. Researchers at the University of Akron and the University of North Texas found that the secret to the gecko’s grip lies on the underside of its toe pads, which bear tiny, sticky hairs called setae. When the reptile walks, it rolls its toe pads onto the surface. Then it peels off its toes forcefully and abruptly enough to dislodge the dirt particles from the setae, leaving its feet clean and sticky as before. This mechanism could inspire reusable, strong-binding duct tape and other adhesives that can function where today's adhesives do not, possibly leading to applications in underwater or space exploration.    

 

 

5.) Growing vegetables with seawater and solar energy: Imagine cool, sprightly cucumbers growing in the middle of the world’s hottest desert. The Sahara Forest Project has made that possible, with United Nations Climate Negotiations participants dining on the first harvest last November. The 10,000 square-meter pilot facility in Qatar, which opened in December, hosts greenhouses irrigated by seawater. Engineers came up with their design by studying animals that have already evolved mechanisms for keeping cool in the desert, such as the camel, whose nostrils evaporate and condense moisture, and the Namibian fog-basking beetle, which extracts water from the balmy night air.

The project is also based on a closed-loop, zero-waste natural ecosystem, instead of a linear, wasteful industrial system. The greenhouse's operation relies on the temperature difference between warm surface seawater and cool water plumbed from deep underground. Both water sources flow to the site through separate pipes, pumped along by solar power. The warm surface water streams over an "evaporative hedge," where, as you might guess, it gets evaporated by the desert air. In turn, the surface water chills and dampens the desert air. That air then passes over the plants, keeping them cool and hydrated. Then the air travels past the pipes that pump the cold water from deeper underground, condensing into fresh water. Meanwhile, the seawater can be used to grow algae, which can help produce biofuels. In the future, similar greenhouses could be built to provide food, fresh water, green energy and employment across the Sahara and other desert regions. 

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Read More:

Innovate: Solar Designs from Nature

Nature-Inspired Robots Fly, Swim, and Run

Act: Slow the Flow


--by Melissa Pandika

--photos courtesy of the University of Akron; Lisa Ventre, University of Cincinnati; Optics Express; Nicolas André; Peter H. Niewiarowski; and the Sahara Forest Project

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