Biomimicry is a method of innovation that has already had resounding success during its history. We invite you here to review the five most emblematic examples who have contributed to making biomimicry known as a successful method of innovation to the general public.
The first emblematic example of biomimicry: Velcro
Velcro, commonly known as scratch
The Velcro is arguably the most famous example of biomimicry. It is a closing system whose operation is simple: on one side a surface on which are arranged hundreds of small hooks, on the other another surface covered with hundreds of small curls. When the two surfaces are pressed together, the hooks grip the loops and form a reliable, reversible closure system and solid. It is a system that has the advantage of being able to be undone quite easily if sufficient force is exerted, while being perfectly reusable. Depending on the materials used for the hooks and loops, Velcro is capable of withstanding impressive forces: did you know that a square of 5 centimeters Velcro side is capable of supporting a 80 kg mass! These properties have given Velcro a wide variety of applications, ranging from our school sneakers to NASA shuttles!
Burdock: the biological inspiration behind Velcro
Velcro is an exemplary case of biomimicry as it relies on the burdock dissemination technique, a common plant in our countryside. The fruit of burdock, which contains its valuable seeds, is covered with small hooks. When passing furry animals (mammals), burdock fruits cling to their fur and are thus disseminated at distances of several tens of kilometers: an ingenious way for an immobile plant to conquer new territories by exploiting the mobility of animals! This dissemination strategy is called zoochory, and has was directly the origin of the invention of Velcro by biomimicry.
How and by whom was Velcro invented?
In 1941, the Swiss engineer George de Mestral returns from a hunting trip. His dog, Milka, who spent her morning hanging out in the thickets, has her hair densely covered in burdock fruit. Removing them one by one requires George de Mestral a lot of patience. He had all the time to observe the operation of those tenacious little fruits. Out of curiosity, he analyzes some of them under the microscope and notices that their hooks are deformable and return to their initial position when plucking them from the hairs. That's how he got the idea to make a quick closing system, which will become one of the most emblematic examples of biomimicry!
The second key example: the Shinkansen
The Shinkansen, an aerodynamic Japanese train
The Shinkansen, famous Japanese train, forerunner high-speed lines, is undoubtedly the second most emblematic example of biomimicry. Circulating at more than 300 km/h, it is one of the most reliable trains in the world. On the island of Honshū, it connects the districts of the Tokyo agglomeration (the most populous in the world with its 42 million inhabitants), to the cities of Nagoya and Osaka in a very dense urban continuum and more importantly, in a very rugged geological environment. The route of the Shinkansen lines therefore includes many tunnels to cross cities and mountains. However, it turns out that every time he entered a tunnel at high speed, the Shinkansen generated a shock wave causing significant noise pollution. However, in the context of very strong urbanization of the Japanese population since the end of the Second World War, the problems of noise pollution have become increasingly important over time. Since the 1980s, it became essential to find a solution to the noise pollution of the Shinkansen in such a densely populated area.
The kingfisher, the origin of the optimization of the Shinkansen
The kingfishers (family Alcedinidae) are birds found on all continents except Antarctica. They are specialize in stalking fishing: they spend much of their time perched above shallow water and dip their beaks forward to grab small fishes that venture close to the surface. A true concentrate of technologies, the kingfisher has, among many other things, an eye capable of correcting chromatic aberrations caused by light reflecting in water. This allows him to see very clearly what is happening below the surface when we only see a reflection of the sky. On the other hand, what allowed the Japanese engineers to solving their problem is the shape of its beak. Indeed, when they split the surface of the water, these small birds manage to generate almost no splash, which allows them to reach prey more than twenty centimeters from the surface with greater speed and discretion. In calm weather, when the water surface is smooth, their hit rate is just… 100%. The secret of this hydrodynamics lies in the shape of its beak: long, thin, spearhead, and streamlined in perfect continuity with the shape of his skull. It is this mouthpiece which, through biomimicry, enabled the Shinkansen engineers to solve the problem of noise pollution.
In particular, Eiji Nakatsu, railway engineer who worked on the Shinkansen project, is behind this biomimicry innovation. Also an ornithologist, he had observed the kingfisher in fishing action. He noticed that the Shinkansen and the kingfisher shared similar constraints: the bird's beak, like the front of the train, suddenly encounters strong resistance. By using biomimicry, he was inspired by the shape of the beak of the kingfisher, to redesign a new nose for the Shinkansen. And the models he made confirm that this track was the right one. When it entered service in 1997, the Kingfisher-inspired Shinkansen 500 offered:
A reduction in the boom at the entrance to the tunnels and a quieter runningin general;
A 15% reduction in power consumption;
A 10% speed increase.
This is an iconic example of biomimicry. It highlights one of the essential components of innovation in general, and of biomimicry in particular: multidisciplinarity. That's because Eiji Nakatsu was both engineer and ornithologist that he managed to transpose the obvious he observed into an industrially applicable solution through biomimicry.
The hydrophobia of the lotus: one of the best-known examples of biomimicry
The sacred lotus is a water flower prevalent in a large majority of Asia. Lotuses live in colonies in shallow water. They often create a rich ecosystem of amphibians, birds and insects: their large leaves form a carpet on the surface of the water on which many organisms move by depositing solid bodies (mud, excrement, particles, etc.). However, the lotus depends on the photosynthesis of its leaves to survive. If particles prevent light from reaching the surface of its leaves, or not limit it in place, it will result in lower energy performance. Evolution led the lotuses to develop an elaborate technique to optimize their energy performance: the superhydrophobia . The principle is simple: the lotus leaf surface structure so much prevents adhesion particles and water, that the slightest drop of water carries with it all the dirt on the surface of the sheet. Thus, the lotus leaf surface is self-cleaning. It is this feature that has inspired many innovations through biomimicry.
The lotus effect: what is it?
The superhydrophobia of the lotus was known for centuries but could only be explained with the invention of the electron microscope, it was only once it was understood that it could be at the origin of innovations by biomimicry. In the 1970s, the German botanist Wilhelm Barthlott solved the mystery. This is explained by villi on the surface of the leaf, themselves covered with micro-villi. This double villi structure creates a nano-scale roughness. This roughness creates so few contact points between the drops of water and the sheet that the drop “slides” over the surface, carrying with it all the micro-particles of dust or dirt. It is this nanometric structure that has inspired numerous applications by biomimicry.
Hydrophobia on lotus leaves vs water lily leaves
This discovery de Wilhelm Barthlott gave birth to industrial applications since the 1990s. Applications can be found in many sectors: self-cleaning paints for facades in construction, coatings for hydrophobic glass, superhydrophobic textiles and synthetic leathers, etc. Recently, solar panels reproducing the particular nanometric structure of the lotus have been developed to obtain the self-cleaning hydrophobic effect and, like the lotus leaf, to optimize their capture of solar energy.
Since the discovery of the lotus effect, we have noticed that many other plants have similar properties such as nasturtium or… leek!
Shark skin: the 4th leading example of biomimicry
Sharks: a rich biological organism for biomimicry
Sharks have colonized all the seas and oceans of the globe. There are about 500 different species. There are many reasons for this evolutionary success. Their highly developed olfactory system allows them to spot their prey from great distances underwater. In addition to this sense of smell, they are equipped with sensory organs called “Ampullae of Lorenzini” that allow them to detect electromagnetic fields present in water as well as temperature gradients. They are thus able to spot a muscle contraction and therefore locate their prey. But there's another characteristic of sharks that gave them an advantagecertain: their ability to move easily in water. While not all sharks actually have a hydrodynamic shape, they do have an amazing feature that allows them to greatly increase their ability to move through water with little energy expenditure: the structure of their skin.
The hydrodynamics of shark skin
Unexpectedly, the shark skin is very rough to the touch. Contrary to our intuition, hydrodynamics are not optimized by a perfectly smooth surface. On the contrary ! Shark skin is actually made up of a myriad of small scales which are entangled. These small scales have the particularity of having micro-grooves on their surface, which generate a sort of “film” of water which limits friction of the shark's body with the fluid. This is called a flow control technique. This is what reduces friction and allows the shark to move at low energy cost.
This amazing structure has spawned a wide variety of applications in hydro- and aerodynamics. Aeronautics, that is no stranger to biomimicry, grabbed the opportunity. The aircraft manufacturer Airbus was inspired by it to develop a coating for aircraft intended to reduce fuel consumption. The tests were very conclusive and allowed to reduce drag by 10% : which would result in fuel savings of more than 1% ! It's colossal! In 2019, Airbus announced the upcoming commercialization of this coating which is a very eloquent example of biomimicry.
But that's not all! Biomimicry has found other applications for this amazing structure of shark skin. The scale microstructure has a height to width ratio that prevents the attachment of microorganisms, and their overgrowth. An American company, Sharklet Technologies, was inspired of these micro-grooves present to create a structurally antibacterial surface. Groove pattern and size (2 microns wide and 3 microns high) prevents bacteria colonies from adhering and colonizing the surface . The applications of this technology are very promising in the medical sector: for example for dressings, adhesive films (to protect surfaces), catheters, etc. Depending on the type of surface, the proliferation of bacteria is reduced by 70 to 97%!
Biomimicry made it possible to imagine other applications to this shark skin structure. For the creation of swimming suits, or the design of antifouling coatings for boat hulls. After a long stay in the water, microorganisms develop on their hull (submerged part). These can increase the drag of a boat by 30% to 50%! Today the fairing is expensive and requires the use of harmful chemicals to clean the hull and repaint it. A antifouling structure inspired by shark skin could allow better efficiency with much more limited use of chemicals!
Here is another example of biomimicry that shows the diversity of applications that can be inspired of a single characteristic of life!
Gecko Skin: Latest Iconic Example of Biomimicry
Do you know geckos? They are little nocturnal lizards that we often surprise on summer evenings behind the shutters of houses in the south of France. Big eyes, a stocky body, star-shaped paws with thick fingers, and always upside down. There are many species, widespread on all continents and with very different aspects. Some have the ability to copy the shape of their support to camouflage themselves, a strategy called mimicry. But they all share a common characteristic : the amazing ability to be able to walk on any vertical or sloped surface as comfortably as we can on level ground. It is not uncommon to see them running along the walls or even on a window!
Gecko's paw grip
The secret to this ability lies in the structure of its legs. Or rather… the hairs of its paws. Indeed, the fingers of geckos are covered with very dense microscopic hairs: the setae. There are several thousand of them per mm2. Each of these hairs is branched at its end into several other small even finer hairs. This density of hair leads to an interaction at the molecular level with the support on which the gecko evolves. This molecular interaction is called “Van der Waals force”. It is a low intensity electrical interaction between atoms that creates a adhesion between the setae and surface. Thanks to these millions of hairs, the gecko is able to browse any surface. And it is this characteristic that biomimicry tries to exploit.
These hairs were discovered in 2005! Since 2005, many biomimicry innovations took inspiration from this principle to look for solutions of reversible adhesion. For example miniature robots capable of climbing on glass, or Geckskin, a structural adhesive, stickable/peelable, without adhesive substance or chemicals, which holds by the only force of Van der Walls. The gecko is famous in biomimicry because of the significant amount of ongoing research that is inspired by the structure of its legs, and by the promising prospects offered by movement on any surface. In 2015, a Stanford researcher managed to climb a glass wall thanks to a assembly of adhesive plates inspired by the paws of the gecko.
These 5 emblematic examples of biomimicry are the best known to the general public, and which are invariably found in all popular publications on biomimicry. They are indeed eloquent, but they are only the tip of the iceberg. Indeed, there are thousands of other bioinspired technologies already developed, and many more to be invented!
The biodiversity is an endless source of inspiration for innovation. Biomimicry is still a very new research and innovation methodology, which largely remains to be explored.