Biomimetics and biomimetic clothing: An introduction from Explain that Stuff!

Lessons from nature

When a German engineer called Otto Lilienthal (1848–1896) strapped wings to his arms and jumped off a hill in an attempt to fly, many people thought he was crazy. They had a point: he did, eventually, kill himself trying to fly like the birds. But his pioneering glider experiments inspired the Wright brothers to develop their engine-powered airplanes in the early 20th century and played a hugely important part in the history of human flight.

The Wright brothers flying the first engine-powered plane at Kitty Hawk in 1903

Photo: People learned to fly by copying birds. The Wright brothers making their historic powered flight at Kitty Hawk, North Carolina in December 1903. Photo courtesy of Great Pictures in NASA.

Lilienthal the "birdman" is only one example of how nature has inspired inventors. How about the story of British engineer Marc Isambard Brunel (1769–1845), father of famous engineer Isambard Kingdom Brunel (1806–1859), who invented a new way of digging tunnels underwater after watching a worm burrowing through the wooden planks of a ship? Or what about Swiss engineer George de Mestral (1907–1990), who invented the amazingly useful fastening material called Velcro after seeing how stray burrs from the burdock plant stuck like glue to the fur of his dog.

Before synthetic textiles such as nylon and polyester were developed in the 20th century, people only ever wore clothes made from natural materials like leather, wool, silk, and cotton. Now synthetic fibers have proved useful in all kinds of ways. Nylon, for example, is strong, hard-wearing, easy to clean, and quick-drying—so it's a popular choice for outdoor clothing. But wearing simple, ordinary nylon is a bit like wrapping yourself up in a plastic bag. Very quickly, you start to sweat—and on a hot, rainy summer's day you can easily become wetter through perspiration than you would have done just by letting the rain in. Natural materials like leather are much "smarter" than this: they let perspiration flow out but stop rain leaking in at the same time. What makes us think our synthetic materials are automatically better than the ones we can find in the world around us? Honed by millions of years of evolution, nature's materials have many lessons they can teach us.

Soggy sheep

If you've ever gone walking on a mountain in winter, you've probably marvelled at how sheep can survive in damp, cold, and utterly horrible conditions. The explanation is simple: wool is an amazingly good insulating material. The best wool of all comes from a breed of sheep called the merino; that's why sportswear companies use in their high-performance base layers (insulating underwear for active sports like climbing, cycling, and surfing).

Sheep flocking in a field

Several brilliant features make merino the perfect thermal underwear for sheep. First, it has much finer fibers than ordinary wool. Finer fibers means more fibers and more air trapped between them. It's trapped air that gives you warmth in clothing (that's why wearing several thin layers is generally warmer than wearing one thick pullover). You can also fluff up the surface of merino so the fibers occupy more space and trap even more air—giving more thickness and insulation with no added weight. All dry wool (and merino wool in particular) has an amazing ability to mop up steamy moisture from inside it and merino can absorb over a third of its own dry weight in water. As the moisture soaks into the fiber, it turns from a gas to a liquid, giving off what's called latent heat of fusion. If you wear polyester clothes and you sweat, the sweat will evaporate from your skin and cool your body down, which probably isn't too helpful if you're climbing a mountain in midwinter. But if you're wearing a merino base layer and you start to sweat, the merino will give off heat as it gets wetter and help to keep you warm!

Photo: Sheep are built to stay warm, even when they're wet.

Clothes that clean themselves

lotus flower

Photo: The leaves of the lotus plant (Nelumbo nucifera) are self-cleaning. Photo taken in the Wichita Mountains National Wildlife Refuge by Elise Smith, courtesy of US Fish & Wildlife Service.

One of the most irritating things about clothes is that you have to keep washing them to keep them clean. Animals wash, clean, and preen themselves too—but you don't often see plants doing the same thing. That's because some plants, like the lotus, have a clever built-in mechanism that naturally keeps them clean. The leaves are coated with nanoscopically tiny bumps and the bumps are, themselves, covered with a thin layer of wax. Dirt particles balance precariously on the waxy bumps but never get a really good grip on the main surface of the leaves below. When it rains, water droplets roll down the leaves, pulling the dirt particles free and washing them clean. The nano-bumps work a bit like a natural detergent, holding dirt clear of the leaves so water can easily wash it away. Surprise, surprise, clothing manufacturers are now coating garments like skate pants with nanofibers so they work in a similar way. The idea is that dirt is held slightly apart from the main fabric so stains cannot penetrate deeply; clothes coated with nanofibers can be washed clean much more easily.

Waterproof and breathable

Take a look at our article on GORE-TEX® to find out how this revolutionary synthetic material lets out perspiration but stops water getting in at the same time.

Swim like a shark

Skin is an amazing material: it's waterproof, it's breathable, it helps to regulate our body temperature, and it can repair itself automatically. One thing it was never designed for was swimming. Water doesn't flow well past human skin—not least because our skin starts to wrinkle (by absorbing water) after we've been swimming or bathing for some time. If you have a particularly hairy body, every single one of your hairs will drag and slow you down even more.

A shark swimming underwater

Photo: Unlike humans, sharks are designed to slip easily through water. Photo of a Black-tipped shark swimming through a coral reef in Guam by Steven Maksinchuk courtesy of US Navy.

A few years ago, the Speedo company found a solution to this problem by designing a swimsuit to mimic a shark's skin. Known as FASTSKIN, the tight-fitting suit is covered with tiny v-shaped channels, just like the ridges (technically known as placoid scales or dermal dentricles) on a shark's body. The idea is that water whizzes along these channels, reducing drag and turbulence, so you can swim faster. The suit also fits very tightly and, by compressing the swimmer's muscles, helps to reduce fatigue. According to Speedo, swimsuits like this can boost a swimmer's speed by up to 3 percent. It's hardly surprising that many Olympic swimmers now wear suits like these.

Open sesame?

You probably know an easy way to tell the weather. Get a pine cone and watch whether the spines open and close. If it's going to rain, the spines close up to protect the seeds inside; if it's going to stay dry, the spines open up to improve the chances of the seeds escaping. Researchers at England's Bath University and the London College of Fashion are trying to design biomimetic clothes that could work the same way. The fabric could be made with an outer layer of tiny spikes, only 1/200th of a millimeter wide. When it's hot, the spikes would open up to let out the heat, cooling you down. When it's cold, the spikes would flatten back down to trap air and provide more effective insulation.

Tomorrow, we could all be wearing clothes based on shark skin, merino wool, pine cones, or a thousand other naturally good ideas. Getting back to nature has never been more worthwhile—or so much fun!

Biomimetic clothes

Lessons from nature

Soggy sheep

Clothes that clean themselves

Waterproof and breathable

Swim like a shark

Open sesame?

Further reading

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