[sushobhan]

UNDERSTANDING BIOMIMETICS

Basically, biomimetics uses ideas and designs from nature and implements them into another technology or field such as engineering, design and computing. Plants and animals in nature present solutions to the same kind of problems that scientists and engineers confront today. As a result, biologists, designers and engineers are increasingly working together, using these solutions from the natural world. Another way of looking at the situation is to say that nature holds many answers for free. Why devise elaborate solutions when something can be borrowed from nature? If plants and animals are such successful machines, why should we not learn from then?

The concept is very old. The Chinese wanted to make artificial silk 2000 years ago, Leonardo da Vinci wanted to fly 400 years ago. The trick is to understand the mechanisms and materials which we are trying to copy. Future advances in biomimetics rely on the collaboration of researchers working in different fields such as biology, physics, chemistry, mechanical engineering and the medical sciences.

VELCRO - The hook-loop fastener was invented in 1941 by Georges de Mestral, a Swiss engineer. The idea came to him after he took a close look at the Burdock seeds which kept sticking to his clothes and his dog's fur on their daily walk in the Alps, during the summer. He examined their condition and saw the possibility of binding two materials reversibly in a simple fashion. He developed the hook and loop fastener and submitted his idea for patent in 1951. De Mestral named his invention "VELCRO" after the French words velours, meaning 'velvet', and crochet, or 'hook'. The uses and applications of the product are numerous. Today, the VELCRO mark is the subject of more than 300 trademark registrations in over 160 countries.

THE EIFFEL TOWER - In the early 1850’s anatomist Hermann von Meyer was studying the part of the femur that inserts into the hip joint. The femur head extends sideways into the hip socket, and so it bears the body’s weight off-centre. It was found that the load is supported due to the existence of a tiny lattice arrangement of bones on the head of the femur called trabeculae.

Swiss engineer Karl Cullman showed that the trabeculae were effectively a series of studs and braces arranged along the lines of force generated when standing and that this was one of the most efficient ways of supporting off-centre weight, a finding that underscores the benefits of taking designs from nature.

The basic concept of building along the lines of force inspired French structural engineer Gustave Eiffel to design the tower that bears his name. Eiffel used a lattice of studs and braces to support the curved structure of the tower, similar to the way that the trabeculae support the curves in the head of the femur. So biomimetics enabled a structure to be designed that was capable of efficiently supporting a structure with an off-centre load distribution. The same principle was used to design the World Trade Centre and other skyscrapers.

ROBOLOBSTERS - Lobsters have a keenly developed sense of smell, which they use to detect and trace the odor of their food to its source in the ever-turbulent ocean. Scientists working in a new field known as biomimetic robotics believe that humans can solve real-world problems by dissecting this and other forms of animal intelligence, and then using that knowledge to design, build, and program autonomous machines with similar superhuman capabilities. Eventually, such robots could be used to track and pinpoint underwater sources of pollution, detect and locate mines and other unexploded ordnance, and even troll the ocean's depths for thermal vents and other locations offering untapped natural resources.

THE LOTUS EFFECT - In 1982 botanist Wilhelm Barthlott of the University of Bonn in Germany discovered in the lotus leaf a naturally self-cleaning, water-repellent surface. The secret lies in waxy microstructures and nanostructures that, by their contact angle with water, cause it to bead and roll away like mercury, gathering dirt as it goes. Barthlott patented his discovery, calling it the Lotus Effect. Barthlott patented his discovery, calling it the Lotus Effect. It has found commercial application in products like the biomimetic paint Lotusan (on blocks above). Infused with microbumps, the paint is reputed to repel water and resist stains for decades.

THE BLADES - Translating whale power into wind power, biomechanist Frank Fish helped design turbine blades with tubercles (nodules) inspired by the flipper of a humpback whale (above, from a deceased animal). The flipper's scalloped edge helps it generate force in tightly banked turns. The whale-inspired blades are being tested at the Wind Energy Institute of Canada to see if they can make more power at slower speeds than conventional blades, and with less noise.

THE SHARK FACTOR - An electron micrograph reveals sharkskin's secret to speed: tooth-like scales called dermal denticles. Water "races through the microgrooves without tumbling," says shark researcher George Burgess, reducing friction. "It's like a fast-moving river current versus the gurgling turbulence of a shallow stream." The scales also discourage barnacles and algae from glomming on—an inspiration for synthetic coatings that may soon be applied to Navy ship hulls to reduce such biofouling. "No shark will mistake me for one of its own," says ten-time Olympic medalist Gary Hall, Jr., training at Florida's Race Club. But sharkskin denticles spurred the design of his Speedo Fastskin, whose texture functions to reduce drag, bumping up speed.

THE BOWFLY - The flutter of the micromechanical flying insect doesn't yet match that of the blowfly, but the robot could soon take flight untethered. Powered by tiny electric actuators along its sides, the bot's fragile wings beat up to 275 times per second, even faster than the bug's that inspired it. "A true fly's wings are remarkable, rotating in every stroke," says UC Berkeley's Ron Fearing. "Our challenge is to get a working mechanism in a device one-twentieth the weight of a paper clip."

STICKYBOT - A tokay gecko's toes sport spatula-tipped hairs (some 6.5 million of them per toe) that adhere to surfaces at the molecular level, giving the lizard nimble footing even on walls and ceilings. Stickybot, at Stanford University, makes a foray onto similar terrain. Bristled toes grab and let go, and the bot's limbs mimic the gecko's own anatomy. But so far it moves at a relative snail's pace. Designers hope it may one day be used in search-and-rescue applications.

THE ADHESIVE ISSUE - A scanning electronmicrograph of a biomimetic adhesive designed by Ron Fearing of the University of California, Berkeley, and colleagues reveals a carpet of microfibers inspired by the hairs on a gecko's toes. When pressed to a smooth surface, the fibers mimic the gecko hairs' ability to "stick" via molecular attraction. More than 40 million microfibers per square centimeter create remarkable grab: A person wearing a glove covered with the material could hang from a glass wall. Millions of tiny hairs with spatula tips give the gecko's toes a powerful "stickiness." Just as remarkable is how quickly it can let go. A tokay gecko needs only about 2,500 of its setae (toe hairs) to hold its body upside down. "If all 6.5 million setae were attached simultaneously," says biologist Kellar Autumn of Lewis and Clark College in Oregon, "they could support 130 kilograms [287 pounds]. Yet the animals manage to remove their feet in milliseconds without measurable force"—a phenomenon related to the angle of the hairs (about 30 degrees) as the foot lifts off.

NATURE's ENGINEERING - Nature's engineering virtuosity is captured in a museum specimen of a fly trapped in amber. Using an electron microscope to zoom in on the eye of a similarly preserved fly, biologist Andrew Parker was intrigued by fine striations on its surface that seemed to reduce light reflection. He worked with optical engineers and combed museum collections for other antireflection designs. Now such bug-inspired technology has been adapted to dampen reflection on computer monitors and solar cells. In the 1960s scientists studying moth eyes at the nanoscale level discovered that their multifaceted surface (electron micrograph, right) is structured to reduce reflection. Engineers at Holotools in Freiburg, Germany, use lasers to sculpt similar facets on a photosensitive lacquer. Some 16 million "dots" of texture per square millimeter all but eliminate the glare on the right half of a computer monitor. It's an advanced biomimetic technology 40 years—plus eons of evolution—in the making.

THE FINAL SAY - Biomimeticists do not usually copy nature exactly. For one thing, as part of living creatures, biological designs generally must be compatible with ambient temperatures and other life-friendly conditions. Biomimetic designs are free of these constraints so they can go beyond nature. For example, feathers insulate birds as well as help them to fly. Hence, it would be misplaced to simply copy the shape of a feather when designing the wings of an aeroplane. A fundamental point of biomimetics is more advantageous to understand the principles of why things work in nature than to slavishly copy details.