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Cockleburr Seed: Source
Velcro being pulled apart:Tracy E. Anderson/ The Nikon Small World Photomicrography Competition
1 Biomimicry or biomimetics is a special type of biotechnology that observes and studies living organisms in order to mimic or copy their structures or processes. These copies are used to produce objects useful to human beings. One of the scientific instruments used to understand the mechanical structure of organisms is the light microscope. It has been used to help create objects that depend on the observation of the details of living organisms. One example of this is Velcro which depended on the observation of a Swiss inventor, George de Mestral in the 1940s, who one day noticed his dog’s fur covered with seeds of the cocklebur plant after a run in the countryside. This made him think whether a similar hook-and-loop fastener could be made. His resulting invention in 1951 was made from nylon, a synthetic material that had been invented in 1937.
2 It is interesting to see this biomimetic invention used in space in the International Space Station (ISS) where Velcro’s hook-and-loop structure is used to keep objects attached to a surface.
3 A light microscope, which helped in the invention of Velcro, however, has limits to magnification. This is because light waves themselves are very tiny or nano-sized. So when a light microscope is used to observe an object, the limit to magnification is set by the size, i.e. the wavelength, of light (Forbes, 2006). This limit to magnification power of an optical microscope is called the “Blind Zone”.
4 So unlike a mechanical structural system like that seen in the plant which inspired Velcro, the tiny parts of a more complex system like the gecko’s foot cannot be seen with a light microscope. Furthermore, it is not enough to focus on the tiny parts of an organism, but it is necessary to understand the interconnections between them. Today, the enabling technology for biotechnology in general, and biomimetics in particular, is the electron microscope because it is able to observe nanostructures better than the light microscope.
5 Robots have been developed by scientists to perform repetitive tasks, as in the manufacture of objects in factories. These robots can also be programmed to carry out dangerous work, such as after an earthquake. Movement is a necessary function of a robot and scientists have always been interested in the gecko’s ability to move vertically across a surface or even position itself upside down. By mimicking its ability to seemingly adhere to surfaces, bioengineers hope to create robots that would move more effectively across all types of surfaces.
6 A gecko’s foot has hundreds of uneven surfaces or ridges called lamellae. Each lamella has hundreds of thousands of tiny hairs called setae. There are about 14,000 setae in each square millimetre of the gecko’s foot with a diameter of 5 microns, i.e. 0.005 mm. Each seta divides into hundreds of even smaller hairs called spatulae which have a diameter of 0.2 microns apiece (Hansen and Autumn, 2005) which is below the shortest wavelength of visible light. There are billions of spatulae in a gecko’s foot. These spatulae interact with the climbing surface at a nano-level and stick to it. Although the force with which each spatula adheres to a surface is tiny, the billions of spatulae enable the gecko to attach itself strongly to any surface. It was realized that the gecko’s foot is a one-way directional adhesive unlike glue or tape. When the gecko changes the direction of its foot, it can remove its foot from the surface (Blackman, 2010).
7 All this information would not have been possible without the use of the electron microscope which is the enabling tool of nanotechnology that is contributing to the increased study of nature as a model for future scientific advances in understanding the world around us.
Note: The words in bold are assessed. See Unit 6 Vocabulary The words in italics are in the glossary below.
Glossary
Glossary
Cocklebur (n) - Any of a genus (Xanthium) of coarse plants of the composite family, bearing closed burs and growing commonly as a weed.
Magnification (n) - Magnification is the degree to which a lens, mirror, or other device can magnify an object, or the degree to which the object is magnified.
Wavelength (n) - A wavelength is the distance between a part of a wave of energy such as light or sound and the next similar part.
Nanostructure (n) - A structure, especially a semiconductor device, that has dimensions of only a few nanometres.
Understanding the text - skimming & scanning
Understanding the text - skimming & scanning
What is the “Blind Zone”?
What type of structures can the electron microscope enable scientists to study?
Which part of a gecko’s foot cannot be seen with a light microscope?
In what way is a gecko’s foot different from other adhesives?
analysing the text: Identifying main ideas
analysing the text: Identifying main ideas
Read Text 2. What is the main idea of each paragraph?
P1: _________________________________
P2: _________________________________
P3: _________________________________
P4: _________________________________
P5: _________________________________
P6: _________________________________
analysing the text: critical thinking
analysing the text: critical thinking
Why do you think it is necessary to keep ‘objects attached to a surface’ in the ISS?
Do you think de Mestral examined the cocklebur under the light microscope to help with his invention? Explain.
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