Riding the bullet train was one of the highlights of my trip to Japan in December 2018. All through my childhood I had heard about the trains that zip across the country at impossibly high speeds. When I saw the train pull into the station, the first thing that struck me was how unusual the head of the train was. Unlike a bullet, the head of the train was flat and sleek. However, once the train took off, it lived up to its name. We shot through the landscape, travelling at 285 km/h (178 mph). How did engineers design this marvel?
The answer lies in nature. Years of evolution has streamlined nature’s designs and serve as an inspiration to engineers. The process, known as biomimicry, has influenced design for decades. From bullet trains to buildings, biomimicry plays an important part in our lives. Read on to find out how engineers have used nature’s blueprints to design their own products.
- Bird beaks and bullet trains
Japan was the first country to build a network of high-speed railway lines. The network, known as the Shinkansen, was conceptualized in the 1930s. The first freight line, which was put into use in 1940, could reach a top speed of 200 km/h (120 mph). These trains were dubbed “bullet trains” in 1964 because the 0 series trains had mouths that resembled bullets. However, there was a problem. When the bullet train entered a tunnel, its nose would compress the air inside the tunnel. This compressed-air would expand rapidly as the train exited, resulting in a loud noise known as a “tunnel boom”. In addition to being disruptive, the power of these waves would cause structural damage to the tunnels.
Eiji Nakatsu, a general manager of the technical development department of bullet trains, solved the problem. He attended a lecture on birds in 1990 and realized that he could use the beak structure of kingfishers to design a more streamlined train. Kingfishers move from air to water. This transition from a medium that offers very little resistance to one that offers high resistance to movement is similar to what bullet trains face. They move from open-air, which offers less resistance, to air in the tunnel, which offers more resistance. Kingfishers have long, pointed beaks that reduce surface impact when these birds dive into the water. As a result, instead of pushing through the water, the beak slides in as water flows past it. The engineers used this motif, which resembles two triangles with rounded edges, to design the train’s nose. These beak-shaped trains, launched in 1997, were 10% faster and consumed 15% less electricity, in addition to being silent.
The Azure Kingfisher. The beak increases in diameter from its tip to the head, allowing the bird to wedge its way into the water. Source.
- Burrs and Velcro
Most dog owners can attest to how annoying burrs can be. They get entangled in dog fur and are difficult to brush out because they break apart and continue to stick to the fur. From the plant’s perspective, burrs are useful because they help in seed dispersal. They act as hooks to attach to a moving host and remain stuck until they are removed or get dislodged. However, one pet owner’s nuisance is another’s inspiration. Burrs from the burdock plant inspired the invention of Velcro.
Burrs tenaciously attach themselves on to surfaces, allowing for seed dispersal. Source.
Velcro was invented in the 1940s by Georges de Mestral, a Swiss engineer. After a hunting trip with his dog in the Swiss Alps, he noticed that his pant legs and the dog’s hair were covered in burrs from the burdock plant. He was fascinated at how the seeds were stuck so effectively and he examined the burrs under a microscope. He found that the burrs had tiny hooks that allowed them to latch on to fabrics that have tiny loops on their surface. The idea for Velcro was born. The name is derived from the French word VELour (meaning velvet) and CROchet (meaning hooks).
Although hook and loop fasteners were common, no one had ever attempted to make them in such a small size. De Mestral was met with skepticism when he conferred with fabric and cloth experts in Lyon. Either the loops were too big for the hooks, or vice versa. In the end, one weaver used a small loom to weave two cotton tapes together. When these were pressed together, they fastened to each other like burrs. Later de Mestral discovered that nylon formed robust hooks when sewn under infrared light, displacing cotton as the primary material. Velcro was introduced in 1960, but it was not an immediate success. It became popular after the aerospace industry used it as an aid for getting in and out of bulky space suits. Soon after, the manufactures of children’s clothing and sports apparel realized the possibilities, and the rest is history.
- The Lotus effect
Paint commercials often tout the ability of their products to “self-clean”. This magical property causes dirt to slide off the paint surface, keeping the walls clean. Although this sounds far-fetched the technology is based on the lotus effect. Lotus plants usually grow in muddy waters but their leaves always remain clean. This phenomenon was investigated in the 1970s by Wilhelm Barthlott, a German botanist. He discovered that the surfaces of lotus leaves have tiny bump-like structures (or papillae) with a waxy coating, which repels water effectively. As a result, any dirt that lands on the leaves is washed off. Additionally, this ability to repel water is also seen in insects with large wings, such as butterflies and dragonflies. These insects cannot clean their wings with their legs and so the lotus effect helps to keep their wings clean and maintain their flying capabilities by preventing an unequal load on the wings.
Lotus leaves are “superhydrophobic” meaning that water drops coalesce and roll off the surface instead of sliding and spreading the dirt particles. Source.
The lotus effect was put into effect in commercial products in the late 1990s with the development of self-cleaning paints, glass facades, windows, graffiti walls, and roof tiles, which use water-repelling nanoparticles to coat their surfaces. Using such technology on glass is especially beneficial because dirty glass facades reduce light transmission, resulting in high cleaning costs. Therefore, this technology is often used in solar panels to maintain their efficiency.
- Termite mounds and buildings
Termites are adept at building astounding towers that reach up to 30 feet. For comparison, if humans had to build something similar relative to their height, it would have to be 600 feet taller than the Burj Khalifa, the world’s tallest building. For termites, ventilating these structures is a challenge. They have to maintain an adequate supply of oxygen and ensure that the mounds remain sufficiently cool during the day. To do so, they build mounds that have an outer wall that is riddled with holes. These lead to a labyrinth of tunnels that exit through a series of chimneys. As a result, the hot air and carbon dioxide that is generated by the nest at the bottom exits the chimney and fresh air is pulled in through moist foraging tunnels. Additionally, the chimneys are warmed by the sun, adding an extra push to the hot air that exits.
Termite skyscrapers have effective ventilation systems due to a network of tunnels and high-rise chimneys. Source.
This elegant construction plan inspired Mick Pearce, a Zimbabwean architect who was commissioned to design the Eastgate Center in Harare, Zimbabwe in 1996. Each floor of the building has air ducts running underneath it. These ducts contain concrete blocks with protruding teeth, providing a high surface area that allows them to cool down and heat up efficiently. A series of fans drive the cool air from below into the floors above, and the warm air exits through the brick chimneys that run along the roofs. At night, the cool air is pulled in to cool the concrete structures. The Center costs 10% lesser to operate than a similar-sized building with air conditioning. Additionally, it saved $3.5 million in energy costs during its first five years.
- Beetles and water harvesting
Life in the African Namib desert is hard. The arid wilderness receives only 1.3 cm of rainfall per year. Although acquiring enough hydration is a challenge, the beetle Stenocara gracilipeshas an ingenious solution. The insect pulls water out of thin air. Its shell is covered in tiny bumps that attract water at their tips and repel water at their sides. When the beetle extends its wings, the water droplets from a humid breeze or fog accumulate on its back and run down to its mouth.
Stenocara beetles excel at pulling water droplets out of the surrounding air. Source.
Inspired by this design, scientists modeled the beetle surface by creating different spheres with varied surface textures, such as grooves, bumps, and smooth. They discovered that the spheres that had bumpy surfaces were water magnets. Those that had 1 mm lumps on its surface caught droplets 2.5 times more efficiently than smooth spheres of the same size. Researchers are hopeful that this principle can be used to design water-collection devices that can catch water droplets from the air.
Several companies have been trying to develop such devices. In 2011 Edward Linacre, an Australian scientist, designed the Airdrop water harvester after his country faced the worst drought in a century. The harvester pumps air through a network of underground pipes. The air cools and the moisture it carries condenses. This moisture is then directly delivered to plant roots. The company NBD Nano designed a prototype bottle in 2014 that had both water-attracting and water-repelling properties. They predicted that the bottle would be able to collect between half a liter to three liters of water, depending on the environment. Although there are no devices on the market, it is possible than one day this technology can make droughts a thing of the past.
Engineers are known for their innovative designs. However, as the above examples show, the best designs are sometimes inspired by Nature- the master innovator. By incorporating designs that have been perfected by evolution, engineers could probably build better materials and technology that rivals Nature in its ingenuity.
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Author:
Ananya Sen is currently a Ph.D. student in Microbiology at the University of Illinois at Urbana-Champaign. When she’s not studying oxidative stress, she is busy pursuing her passion for scientific writing. Currently, she contributes articles to ASM, ScienceSeeker, and her own blog where she discusses the history of various scientific processes. She is an ardent reader and will happily discuss anything from Jane Austen to Gillian Flynn. Her graduation goals include covering all the national parks in the U.S. with her sidekick Oscar, a Schnauzer/Pomeranian mix.
Editors:
Saurja Dasgupta is originally from Kolkata, India. He obtained his Ph.D. at the University of Chicago, where he studied the structure, function, and evolution of catalytic RNA. He is currently doing his postdoctoral research at Massachusetts General Hospital, Boston, where he is trying to understand the biochemical milieu that could have given birth to life on earth (and elsewhere) and reconstruct primitive cells. One of his scientific dreams is to observe the spontaneous emergence of Darwinian evolution in a chemical system. When not thinking about science, Saurja pursues his love for the written word through poetry and song-writing (and meditating on Leonard Cohen’s music). His other passions are trying to make science easier to understand, and fighting unreason and pseudoscientific thinking with a mixture of calm compassion and swashbuckling spirit.
Sumbul Jawed Khan received her Ph. D. in Biological Sciences and Bioengineering from the Indian Institute of Technology Kanpur, where she studied the role of microenvironment in cancer progression and tumor formation. During her post-doctoral research at the University of Illinois at Urbana-Champaign, she investigated the gene regulatory networks that are important for tissue regeneration after damage or wounding. She is committed to science outreach activities and believes it is essential to inspire young people to apply scientific methods to tackle the challenges faced by humanity. As an editor, her aim is to simplify, translate, and excite people about current advances in science.
Cover image- Flickr
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