Nature’s useful designs

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What has fins like a whale, skin like a lizard, and eyes like a moth? The future of engineering. Almost all living organisms are uniquely adapted to the environment in which they live, some so well that scientists study them in the hope of replicating their natural designs in technology. This process, called biomimetics, is the crossroads where nature and engineering meet.

B
Perhaps the best example of biomimetics is Velcro. In 1948 a Swiss scientist, George de Mestral, had trouble removing a plant’s prickle which was stuck to his dog’s fur, so he studied it under a microscope. Impressed by the stickiness of the prickle’s hooks, he copied the design, engineering a fastener made of two pieces. One piece has stiff hooks like the prickly, while the other has soft loops that allow the hooks to stick. De Mestral named his invention Velcro – a combination of words “velour” and “crochet”.

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Andrew Parker, a research fellow at the Natural History Museum in London and at the University of Sydney, is a leading proponent of biomimetics – applying designs from nature to problems in engineering, materials science, medicine, and other fields. He has investigated iridescence in butterflies and beetles and antireflective coatings in moth eyes – studies that have led to brighter screens for cellular phones and an anticounterfeiting technique so secret he cannot say which company is behind it. He is working to make cosmetics that mimic the natural sheen of diatoms (a type of algae) and, with the British Ministry of Defense, to emulate the water-repellent properties of these same creatures. He even draws inspiration from nature’s past: on the eye of a 45-million-year-old fly trapped in amber that he studies in a museum in Poland, Parker noticed microscopic corrugations that reduced light reflection. This feature is now being built into solar panels.

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To Parker, every species, even those that have become extinct, is a success story, optimized by millions of years of natural selection. He asks: why not learn from this? Parker explained how the metallic sheen and dazzling colors of certain birds derive not from pigments but from neatly spaced microstructures that reflect specific wavelengths of light. Such structural color, fade-proof and more brilliant than pigment, is of great interest to people who manufacture paint and holograms on credit cards. Glowworms produce a cool light with almost zero energy loss (a normal light bulb wastes 98 percent of its energy as heat) and bombardier beetles have a highly effective combustion chamber in their posterior that heats chemicals and fires them at would-be predators.

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For all nature’s sophistication, many of its clever devices are made from simple substances like keratin, calcium carbonate, and silica, which are manipulated into structures of fantastic complexity and toughness. The abalone, for example, makes its shell out calcium carbonate, the same stuff as soft chalk. Yet by coaxing this substance into walls of staggered, nanoscale bricks through a subtle play of proteins, it creates an armor 3000 times harder than chalk. Understanding the microscale and nanoscale structures responsible for a living material’s exceptional properties is critical to re-creating it synthetically.

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Though impressed by biological structures, Robert Cohen, an engineer at MIT in the United States, considers biology merely a starting point for innovation. You don’t have to reproduce a lizard skin to make a water-collection device or a moth eye to make an antireflective coating, Cohen says. The biological structure provides a clue to what is useful. But maybe you can do it better. Ultimately, he considers a biomimetics project a success only if it has the potential to make a useful tool for people. “Looking at pretty structures in nature is not sufficient,” says Cohen; “what I want to know is, can we actually transform these structures into something with true utility in the real world?”

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This, of course, is the tricky bit. Potentially one of the most useful embodiments of natural design is the bio-inspired robot, which could be deployed in places where people would be too conspicuous, bored to tears, or killed. But such robots are notoriously hard to build. Ronald Fearing, a professor of electrical engineering at the University of California, Berkeley, has taken on one of the biggest challenges of all: to create a miniature robotic fly that is swift, small, and maneuverable enough for use in surveillance or search-and-rescue operations.

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The key to making his micromechanical flying insect (MFI) work, Fearing says, is not to attempt to copy the fly, but to isolate the structures crucial to its feats of flying. The fly’s wing is driven by 20 muscles, some of which only fire every fifth wing beat, and all you can do is wonder, “what on earth just happened there?” says Fearing. Some things are just too mysterious and complex to be able to replicate.

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For all the power of the biomimetics paradigm, and the brilliant people who practice it, bio-inspiration has led to surprisingly few mass-produced products, and arguably only one household word – Velcro. Some biomimetists blame industry, whose short-term expectations about how soon projects should be completed and become profitable clash with the time-consuming nature of biomimetics research. Others lament the difficulty in coordinating joint work among diverse academic and industrial disciplines, which is required to understand natural structures and mimic what they do. But the main reason biomimetics has not yet come of age is that from an engineering standpoint reproducing such intricate nanopuzzles is difficult. Nonetheless, the gap with nature is gradually closing.