Category Archives: Biomimicry

Adhesive Acrobats: Gecko’s Sticky Feet

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Gecko face

Gecko face

One thing I like about visiting the Southwest is getting glimpses of geckos and their reptilian acrobatics on trees and buildings. They can cling to just about anything and support many times their body weight.   How do they do it and what may we learn from it? Most gecko species can defy gravity due to their brilliantly adapted feet. A vertical pane of glass or even a ceiling is no challenge for them. Those little lizards really stick to it!

Scientists and biomedical engineers have been combing through hairy lizard feet for clues to their stickiness since 2000 when University of California researchers pointed to the role of tiny hair-like structures there called setae. How do geckos gain a grip on glass? The cumulative forces of microscopic “flowing locks” put a lock on it. The setae and their little spatula pads form bonds with whatever surface they touch. The firm yet flexible tendons in geckos’ feet help maintain that bond. Contact is broken when the lizards curl their toes to take another step. That rolling motion also helps keep the foot pads clean.

According to the fossil record, geckos have been around for at least 100 million years. They adapted to their environments, on every continent except Antarctica, in unique ways. They are the only lizards with vocal cords and can chirp, click, and send messages to their fellow geckos. In fact, their name derives from gekoq, an Indonesian-Malay imitation of the noise they make. Their eyes are covered with a transparent layer that they lick to keep clean and are exquisitely sensitive to color, even at night.

But it’s their feet that get the most press lately. Who doesn’t want to have gecko powers? We wouldn’t need ladders to wash windows or change a light bulb on the ceiling. What about special gloves for rock climbing or catching balls?  More importantly, we could learn from the geckos how to make products to help injured people, such as a tape that could be used in place of sutures.

Scientists at University of Massachusetts created adhesive Geckskin, named one of CNN’s top five scientific breakthroughs of 2012. At Northwestern University, Professor Phillip Messersmith and graduate student Haeshin Lee created another adhesive material, called Geckel, that can be used wet or dry and has a super strong hold–until you release it. Like a sticky note, it can be used over and over, in this case through 1,000 contact/release cycles.

In addition to applying the principles of gecko feet, the researchers copied the adhesive proteins of mussels that help them anchor themselves underwater. Gecko power plus mussel power made for one mighty strong, reusable adhesive. More inventions inspired by nature, i.e., biomimicry, are sure to come.

Gecko foot

Gecko foot

 

This has been another installment of Ms. Tree’s Nature Mysteries: Adventures in Biomimicry by Barbara Terao.

Nature as Mentor

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What is biomimicry?  The term is made up of the Greek words bios for life and mimesis for imitation.  It is an approach to science and product development that relies on learning from and imitating nature.  This is in stark contrast to our usual practice of forcing nature to do our bidding, usually by way of harsh chemicals, high temperatures and/or intense pressure.  (This is how we synthesize plastics, alloys, and many other products in this industrial age.)

The environmental costs of such brute force technologies are so devastating that scientists, engineers, and manufacturers are looking for alternatives.  Many are asking the question, “How does nature do it?”  For instance, certain plants filter water to purify it; no chlorine needed.  How can we mimic that?

Science writer Janine Benyus described biomimicry in her book by that title as “a new science that studies nature’s models and then imitates or takes inspiration from these designs and processes to solve human problems, e.g., a solar cell inpired by a leaf.”  Nature provides myriad models and possibilities for us to consider.

Biomimicry also uses nature as a measure, a standard to meet in finding what works and what is most sustainable.  An animal or a plant cannot afford to pollute or otherwise ruin its own environment, its home, so it finds low impact methods to survive and thrive.  Why not learn from billions of years of innovation and development (aka evolution)?

Benyus goes a step further and says that nature can be a mentor, which is what I have been thinking about for a few years now.  “Biomimicry,” she writes, “is a new way of viewing and valuing nature.  It introduces an era based not on what we can extract from the natural world, but on what we can learn from it.”

What can we learn from prairies and clouds?

What a concept–working with nature!  This is what Aldo Leopold’s “land ethic” requires.  This is the way many indigenous people live, or were living, not because they were more virtuous but because cooperating with nature is what works in the long run.

My previous post told the story of learning from burrs in order to invent hook-and-loop fasteners, currently used in virtually every household in America.  Now products are being invented based on the self-cleaning properties of lotus leaves and the amazing “stickiness” of gecko feet.  (Those little lizards can run straight up a plate glass window!)  This is in part due to high-powered microscopes that allow us to see such things as the tiny bumps on the leaves of the lotus plant, and in part due to our willingness to pay attention to the intelligence of nature displayed all around us.

What can we learn from trees and insects, water and stone? We’ve just begun to find out.

Have You Thanked a Burr Today?

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Dog and burrs

In 1941, a man named George de Mestral went hunting for two weeks in the Swiss mountains.  Switzerland, like many places in the world, has plants with burrs and those burrs stick to anything fuzzy.  By the time George got home, there were so many burrs on his trousers and tangled in the fur of his dog (an Irish Pointer), it took a long time to remove them all.

George got curious.  What made the spiny seedpods grab onto the fur?  De Mestral was an engineer with a scientific mind.  And he had a microscope. (People started developing microscopes in 1590 to examine things too small to see with the naked eye.)  When he looked at a burr under the microscope, he saw that each spine was bent at the end, having what he called in French crochet, which means hook.  The hooks made the burr stick to anything soft that brushed against it—an  ingenious way to scatter the seeds of the burdock plant!

Not only did George admire the plant’s method of seed dispersal, he decided that people could use this same technology, if only he could find a way to manufacture it.  He imagined creating a zipperless zipper and even got a patent for it in 1951.  But it took him many years to invent his version of the burr’s hooks.  He got up at sunrise every morning in his small cabin in Switzerland and tried to figure out how to use nylon, a synthetic fabric, to grab onto velour, a velvety cloth.

De Mestral finally developed a manufacturing process and—voila! Velcro® (a combination of the words velour and crochet) was born.  First, astronauts used it in outer space (very useful in zero gravity), then skiers on their outfits, and pretty soon the new hook-and-loop technology appeared on wallets, clothes, book bags, and shoes.  George de Mestral became a millionaire, moving from his mountain hut to an elegant chateau, all because he learned the secrets of a burr.

One day, when he visited his manufacturing plant in the United States, George gave the bosses there some advice: “If any of your employees ask for a two-week holiday to go hunting, say yes.”  George de Mestral knew that if you go outside and pay attention, you might be surprised by what will stick with you.

This is the first in a series of MS. TREE’S NATURE MYSTERIES, an introduction to biomimicry by Barbara Wolf Terao.