The Gecko's Foot: How Scientists are Taking a Leaf from Nature's Book
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A cutting-edge science book in the style of ‘Fermat’s Last Theorem’ and ‘Chaos’ from an exciting and accessible voice in popular science writing.
Bio-inspiration is a form of engineering but not in the conventional sense. Extending beyond our established and preconceived notions, scientists, architects and engineers are looking at imitating nature by manufacturing 'wet' materials such as spider silk or the surface of the gecko's foot.
The amazing power of the gecko's foot has long been known – it can climb a vertical glass wall and even walk upside down on the ceiling – but no ideas could be harnessed from it because its mechanism could not be seen with the power of optical microscopes. Recently however the secret was solved by a team of scientists in Oregon who established that the mechanism really is dry, and that it does not involve suction, capillary action or anything else the lay person might imagine. Each foot has half a million bristles and each bristle ramifies into hundreds of finer spatula-shaped projections. The fine scale of the gecko's foot is beyond the capacity of conventional microengineering, but a team of nanotechnologists have already made a good initial approximation.
The gecko's foot is just one of many examples of this new 'smart' science. We also discover, amongst other things, how George de Mestral's brush with the spiny fruits of the cocklebur inspired him to invent Velcro; how the shape of leaves opening from a bud has inspired the design of solar-powered satellites; and the parallels between cantilever bridges and the spines of large mammals such as the bison.
The new 'smart' science of Bio-inspiration is going to produce a plethora of products over the next decades that will transform our lives, and force us to look at the world in a completely new way. It is science we will be reading about in our papers very soon; it is the science of tomorrow's world.
was starting to think it might be dangerous when help arrived. A gecko walked across the ceiling and devoured the spider. On his return, he decided that perhaps the gecko’s feet were the most interesting thing after all. Although the gecko’s ability is apparent to anyone who ever saw one, understanding it depends on being able to see the micro-structures on the pads of its feet. An unaided visual inspection offers few clues to their adhesive ability. To our eyes, the pad of the foot is crossed
profile on the upstroke. In any case, if the fly is the model, with its very small wing, too much twisting is not desirable. As Ron Fearing says, if the wing were too bendy ‘it would be like paddling a canoe with a cardboard paddle’. At the 15 cm scale Rafal Żbikowski is working at, a flexible wing is necessary and his team have shown that quite simple synthetic wings, with only two control ‘muscles’ at the root, can bend in ways convincingly like the real thing. Żbikowski has a test bed model
The giant lily has ribs on its 1.5–1.8 m diameter leaves that appear to have been engineered. The Crystal Palace used iron ribwork to support the glass. The Victoria regia water lily was so large Paxton had to build a new greenhouse for it. In 1850, he gave a talk to the Royal Society of Arts at which he demonstrated the lily’s leaf; he said: You will observe that nature was the engineer in this case. If you will examine this, and compare it with the drawings and models, you will see that
1988 (fig. 9.10). David Geiger died in 1989, but in the last year of his life he had built two more cabledomes in America. His firm, Geiger Engineers, continues the work, and cabledomes are increasingly part of the repertoire for roofing large arenas. David Campbell, now CEO of Geiger Engineers, worked with David Geiger as he developed the cabledome. From the Geiger offices in Suffern, New Jersey, some 35 miles from New York, he explained how Geiger ‘started playing around with this idea that
5.10 Alamillo Bridge, Seville 213–14 Albers, Joseph 221 albumen 65 American Physical Society 3 amino acids 10, 15, 17, 66, 138, 238n Ancyluris butterflies 119 anti-counterfeiting devices 118–19 anti-reflection surfaces 121 aphids 53–4 Aphrodita 104, 112–14, 120, 130 aragonite 140–41 architecture 27, 34, 197–230, 232; arches 201–2, 214; cable-hanging 212–14; concrete 204–5, 211–12; domes 210–12, 216–18, 222–6, 230, Figs 9.10–9.11; glass 45, 230; origami-based 195, Fig 8.6; shell