November 25, 2013 | David F. Coppedge

Look Up, Look Down at Natural Design

Swimmers, flyers, and things that just sit in the sun are the envy of bioengineers.

Silent flyers:  How do owls sneak up on their prey in the dark?  The secrets of the near noiseless flight of owls is being studied by Justin Jaworsky and a team at Lehigh University, Science Daily reported.  “Owls possess no fewer than three distinct physical attributes that are thought to contribute to their silent flight capability: a comb of stiff feathers along the leading edge of the wing; a flexible fringe at the trailing edge of the wing; and a soft, downy material distributed on the top of the wing,” he said.  Understanding these principles might help the design of submarines, aircraft and wind turbines.  The work is inspiring future applications: “If the noise-reduction mechanism of the owl down can be established, there may be far-reaching implications to the design of novel sound-absorbing liners, the use of flexible roughness to affect trailing-edge noise and vibrations for aircraft and wind turbines, and the mitigation of underwater noise from naval vessels,” Jaworski said.

Jellyfish in the sky:  Air is a fluid, though it is much less dense a fluid than water.  Borrowing from the graceful propulsion system of jellyfish, the most efficient swimmer in the sea (10/13/13), Leif Ristroph of New York University has built a four-winged aircraft that propels itself upward in the air in a manner similar to jellyfish.  He says this method is much more stable than insect flight, which is much more complex and hard to imitate.  So in a sense, insects and jellyfish both provided inspiration for this flapping machine.  So far, Ristroph has only demonstrated “proof of principle” as he envisions “more sophisticated and complex vehicles” in the future.  (Source: Science Daily)

Bird underwater:  Penguins look awkward waddling on the ice, but underwater, they can really rocket around, “accelerating from 0 to 7 m/s in less than a second,” Science Daily reported.  Inspired by that natural technology by seeing penguins underwater in an IMAX film, Caltech student Flavio Noca, now an instructor of aeronautical engineering in Switzerland, tried to imitate it.  A prototype of his “penguin-inspired propulsion system” that mimics the penguin’s spherical shoulder joint is pictured with the article.   Noca said that the penguin’s method of high-speed swimming is still poorly understood.  “By accurately reproducing an actual penguin wing movement, we hope to shed light on the swimming mysteries of these underwater rockets.”

Fish armor:  “Clad in mail never clinking” is part of a riddle in The Hobbit about fish.  The silent, flexible scales of fish are inspiring MIT engineers to improve military armor.  Live Science describes what has made fish scales attractive for millennia, and how today’s engineers are going about imitating them:

Such bio-inspired armor — also called biomimetic armor, because it mimics nature — has existed for years, even dating back to the Roman Empire, when soldiers wore scaly metallic garb reminiscent of fish or amphibian skin. But recent advancements in 3D printing now allow researchers to mimic, more closely and effectively, these natural structures by creating larger-than-life models of scales and conducting nuanced mechanical tests that identify the specific internal structures that make them so protective.

The team’s plagiarism is not limited to the shape and arrangement of hard scales on dragon fish.  Materials scientist Christine Ortiz is also copying the material:

“What nature does, in many cases, is it suppresses radial cracking in ceramics, and instead, it basically cracks in a circle right around the impact,” Ortiz said during the lecture. “Instead of cracking outward, it actually goes inward, dissipating energy to stop the penetration without sacrificing the structural integrity of the entire system.”

Soldiers are not the only ones who might benefit from the research.  Anyone who needs protection and freedom of movement will thank the fish, including firefighters and football players.  For more on 3-D printing and why it is also a type of biomimetics, see 10/21/13.

How dry I am:  What do nasturtium leaves and butterfly wings have in common?  They have super-hydrophobic surfaces – those that repel wetness by making water bead up and fall off.  The driest-ever waterproofing material has been created at MIT, the BBC News announced, inspired by those two natural wonders.   Its dryness even surpasses the lotus leaf, earlier thought to be the “gold standard” in hydrophobicity (9/23/09).  By imitating the tiny ridges in the nasturtium leaf, the MIT team has improved the dryness of their material 40% over the previous record.  Butterfly wings work even better because their ridges intersect.  An embedded video clip shows water drops bouncing off the artificial imitation like they can’t get away fast enough.  Imagine the raincoats and other products that could benefit from this technology: “Sportswear, lab coats, military clothing, tents – there are a whole range of situations where you want to stay dry.”  Gore-Tex will seem drenched by comparison.  Now that the team has imitated nasturtiums and butterflies, the gold rush is on: “There could be other species in the natural world which are even better.

Make like a leaf:  Efforts to imitate the efficiency of photosynthesis continue.  PhysOrg reported on work in Canada by Dr. Gregory Scholes, a prize-winning expert in photosynthesis.  The article notes that plants can harvest light and send it to the reaction center at an “incredible speed” – a billionth of a second.  The efficiency is astounding:

More than 10 quadrillion photons of light strike a leaf each second. Incredibly, almost every visible photon (those with wavelengths between 400 and 700 nanometers—1 nm equalling 1 billionth of a meter) is captured by pigments and initiates the steps of plant growth.

That’s why the desire to duplicate it.  “This new bio-inspired understanding will help scientists devise artificial light gathering systems that can far exceed existing solar cells in functionality, and so pave the way to new, environmentally-friendly energy technologies,” Scholes said.  His final sentence in the article is a take-home lesson about the value of biomimetic research:

Concludes Dr. Scholes: “Nature has worked out with astonishing efficiency some the [sic] riddles of fundamental importance that vex our species today,” he adds. “If we are hunting for inspiration, we should keep our eyes open for the unexpected and learn from the natural sciences.

Those are just a few of the recent stories pouring out of biomimetics research labs around the world.

Wasn’t this a great set?  Wow.  This is a scientific revolution in progress.  Biomimetics itself is old (like the mention of Romans mimicking fish scales), but only recently have the methods to study nature at the nanoscale enabled really detailed imitation.  There doesn’t seem to be any end in sight.  This is a gold rush young budding scientists should get on.

None of the above articles mentioned Darwin.  Only the last story mentioned evolution briefly, describing bacteria “which have evolved to short circuit photosynthetic light harvesting and thereby warm their local environment.”  That sole mention, though, did not add anything to understanding the origin of photosynthesis.  If anything, it suggested that breaking photosynthesis creates waste heat, a compromise of thermodynamic efficiency – like using an arcing electrical appliance instead of a fireplace.  That’s something evolution is good at (breaking things).  Creating highly-efficient, superb designs is not the work of blind, unguided processes.  No; biomimetics has “intelligent design” written all over it.






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