When nature inspires technology

Home Technologist 10 Biomimicry When nature inspires technology
Butterfly wing scales

Buildings that breathe through pores, robots that move like salamanders or surfaces that shine like the blue wings of a morpho butterfly. These are examples of biomimicry – a dynamic new discipline that looks to nature for stunning examples of functionality and efficiency. Applications range from architecture to medicine to engineering. Nature is proving particularly inspiring when it comes to energy efficiency: London’s celebrated Gherkin skyscraper, for example, consumes half the energy of a traditional tower, thanks to a ventilation system inspired by sea sponges. In biomimicry, as in other cutting-edge fields, interdisciplinary collaboration is key. In the U.S. the number of biomimicry patents, scholarly articles and research grants has increased five-fold since 2000.

Insects in the spotlight

Beetles, butterflies and spiders are some of the bugs that inspire engineers and researchers. What makes these insects so prone to imitation? 

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Inspiration: The white shel of a Cyphochilus beetles. Application: thinner paper and solar cells with better light absorption. Photo: Lorenzo Cortese.

The spectacular blue wings of the morpho butterfly fascinate scientists around the world. Some materials engineers are now trying to build an identical replica of the nanostructures that result in that vivid blue, while others want to recreate those dazzling shades for use in the automotive industry. But this species is not the only one generating such keen interest. All sorts of arthropods are increasingly inspiring biomimetics. “It makes sense because there are tons of insects and spiders on the planet,” says Kalina Raskin from the Biomimicry European Centre of Excellence in Senlis, France. “It’s the branch of the animal kingdom with the largest number of individuals.” There are 6.8 million terrestrial arthropods and 5.5 million varieties of insects, according to a 2015 study.

And materials engineers have found some amazing properties within that rich pool of species, such as the strength of spider silk. The webs woven by certain arachnids can withstand up to 380 tonnes, the weight of a Boeing 747 crammed with passengers. In 2011, Horst Kessler and his team from the Institute for Advanced Study at the Technical University of Munich (TUM) discovered the molecular mechanism that makes silk yarn so sturdy. In 2014, the TUM spin-off AMSilk took these findings and began producing a natural fibre on an industrial scale. By highlighting the fibre’s durability compared to others in plastic, the start-up has been selling its product to companies active in the textile, automotive or interior decorating industries.

Beetles for sale online

The physicist Ullrich Steiner says that insects are particularly practical to study. “Most can be ordered online. They aren’t subject to any strict animal protection laws. And compared with plants, they don’t wither and are more robust,” says the professor from the National Center of Competence in Research (NCCR) for Bio-Inspired Materials at the University of Fribourg. The NCCR brings together 15 research groups from throughout Switzerland, including those from the École Polytechnique Fédérale de Lausanne.

Using the specimens he has ordered online, Ullrich Steiner hopes to reproduce natural photonic surfaces such as the shell on the Cyphochilus beetle. The insect’s most striking feature is its bright white colour, a rare phenomenon in nature. White only occurs when a surface reflects light in all directions. “This species of beetle is as white as paper, but the layer of its shell that produces the colour is 100 times thinner than a sheet of paper,” he says. “If we use our current technology to create something similar, for now the material comes out transparent.” To solve the mystery behind this immaculate shell, the research team works with X-ray nanotomography and computer modelling. If they are able to imitate nature, they could use it in new technology including thinner paper and paint and similar structures for solar cells to improve light absorption.

The main advantage of insects and other arthropods is that they are just different enough from human beings, says Thibaud Coradin, head of the Materials and Biology team at the Chemistry of Condensed Matter Laboratory in Paris. “We won’t be discovering much new about ourselves if we study the biomimetics of mammals. And if we look at species that are too distant, it would be too difficult to adapt findings to our needs. So arthropods – which are neither too far nor too close – represent a good compromise.”

Familiar species

Another advantage of working with insects is that many scientists share a basic knowledge of entomology. “The biodiversity of insects was identified a long time ago, because these are organisms that we see, that we live with,” the French chemist says. “We’re familiar with them and understand many of their characteristics, without being zoologists. So, depending on what we’re looking for, we’ll think of a given species that can fly silently, another that can change colours or another that can live in the water for a long time, and so on.”

The blue colour of the morpho – widely known to butterfly catchers – sparked the curiosity of Anders Kristensen, a professor with the Department of Micro- and Nanotechnology at the Technical University of Denmark. Inspired by the microscopic surface structure that creates the bright colour of the wings, the physicist and his team developed an innovative technology. “We don’t use any dye or pigments, but photonic surfaces,” he says. “We’ve developed nanotextures that are cast directly into the surface of the plastic components.” And the structures are tiny. “They’re cylinders that are 100 nanometres deep and high, coated in a layer of aluminium. That’s what creates the colour using a resonance absorption technique. And last, we add a thin protective layer.” Through the IZADI-Nano2Industry project, mainly financed by the Horizon 2020 European research programme, the Danish scientist is working on producing materials for automotive, agricultural and construction machinery.

Article by Blandine Guignier 


Buildings that live and breathe

From London to Hamburg to Singapore, architects draw inspiration from living organisms to design energy-efficient buildings. 

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Inspiration: Polar bear fur. Application: Surface structure of the Esplanade Theatres in Singapore for better heat regulation. Photo: Warrengoldswain / Dreamstime.

Imagine a building that can breathe through thousands of pores. Sounds outlandish? An engineer from the University of Stuttgart in Germany has recently made it happen. Tobias Becker has designed a façade that adapts indoor temperatures to create a comfortable environment for people in the building. And the energy required is minimal. The system consists of small holes in the surface of the building that open and close to let in just the right amount of air and light.

Tobias Becker drew his inspiration from the skin of living organisms. Skin can regulate its permeability to control the light, heat and other substances that flow between the inside and outside of the body. Becker’s invention is an example of biomimetics or biomimicry applied to architecture. The goal is to imitate biological systems to develop more eco-friendly construction solutions. The European Commission reports that buildings account for 40 per cent of energy consumption in Europe and 36 per centof its CO2 emissions.

“A few years ago, humans were building ‘machines for living’,” says Leonardo Saavedra, a PhD student at the Technical University of Munich (TUM) who is studying the potential of biomimetic applications based on the skin in construction. “But architects now realise the limitations of this approach and are exploring ways of designing more sustainable, energy-efficient buildings.”

Examples of architectural biomimicry abound worldwide. London’s 30 St Mary Axe skyscraper, better known as the Gherkin, features a ventilation system similar to that of sea sponges. The innovation achieves energy savings of 50 per cent over a traditional tower of equal size.

The surface of the Eastgate centre in Harare, Zimbabwe is covered in openings. Its architect designed it after watching how termites bore holes in their mounds for ventilation. The centre has no air conditioning system and only requires a tenth of the energy used by a similar building.

New fur coat

The surface of the Esplanade Theatres in Singapore is modelled after polar bear fur, a highly efficient system for regulating heat. The arts complex is covered in 7,000 triangular shades made of aluminium. Photoelectric light sensors adjust the angle and direction of these “shields” depending on the sun’s rays.

This lets light in while preventing overheating. Energy Star, the U.S. government programme set up to promote energy efficiency, estimates that this type of reflective surface cuts the demand for air conditioning by 15 per cent. “So-called ‘smart façades’ have enormous potential, especially during periods of sunshine,” says Jan Hensen, a professor with the Department of the Built Environment at the Eindhoven University of Technology. “A building envelope covered in photovoltaic panels can be used to collect electricity while also acting as a ‘shield’, for example, thus reducing the need for air conditioning.”

The Centre for Sustainable Building at TUM is also looking into these smart façades. One of the centre’s teams is developing a transparent building surface made with liquids and insulating glass. The liquids control the flow of energy between the outdoors and the building’s interior, while the glass improves its thermal performance. Again, the technology results in signi-ficant energy savings.

The BIQ House in Hamburg has gone a step further by directly integrating living organisms into its structure. Its transparent surface contains micro-algae that affect the amount of light entering the building.

When the sun is shining bright, the algae grow by photosynthesis and filter out the sun’s rays. If there is no sunlight, the algae do not multiply, letting sunlight in. Energy savings can reach up to 50 per cent.

“Today, we have the resources to apply certain biological processes to technology,” Leonardo Saavedra says. “Many natural systems adapt to their environment, providing ideal end solutions.” Luc Schuiten, a Belgian architect who designs futuristic urban ecosystems, believes that bio­- mimetics is just a step towards a future more in harmony with the environment. “Humans have been using destructive building techniques since the industrial revolution. Other methods are available.”

Article by Julien Calligaro


Turning nature into a factory

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Inspiration: The movement of salamanders. Application: An agile robot that could be used for rescue missions and industrial inspections.

How a salamander inspired a robot, a protein became a sensor and a molecule helped design a water purifier. 

The word “industrial” conjures images of cogs, pipes, smoke and metal, per–haps even robots busily assembling the latest product. What it does not evoke is nature. Yet with the number of biomimicry patents, research articles and grants increasing more than fivefold since 2000, researchers and industrialists are increasingly finding inspiration in nature to develop new and improved materials, products, buildings and processes.

Take, for example, the obvious biomimi­cry of the École Polytechnique Fédérale de Lausanne salamander robot (named Pleurobot). Capable of walking and swimming, Pleurobot can replicate the amphibian’s movement to an unpre­cedented degree of accuracy. “The robot has been designed as a scientific tool for neuroscience,” project leader Auke Ijspeert explained during a TedTalk, and yet applications are already being touted – like search and rescue, fieldwork and archaeology, and for industrial inspection, painting and coating.

Bacterial temperature control

Some natural designs, like the salaman- der’s amphibious capabilities, the hedgehog’s armour or the humming bird’s nectar-sipping beak, confer clear evolutionary advantages. Others are a little more mystifying – but could offer huge benefits to industry.

Just this kind of mystery is what Professor Ulrich Gerland and his team of physicists from the Technical University of Munich aimed to illuminate when they joined a project by a group of biologists from Ludwig Maximilian University of Munich (LMU). The project’s aim was to understand the role of a certain protein in Escherichia coli – a bacterium commonly found in the intestines of warm-blooded animals, including humans. “The LMU group already had some evidence that the membrane protein KdpD could be a dual sensor for potassium,” explains Gerland. “The question was why the dual sensor was useful when a single sensor should be able to do the job.”

Testing various designs, it slowly became clear that the dual sensor is better when both the availability and demand for potassium by the bacterium fluctuate. “This suddenly made a lot of sense – the external sensor is a useful design when the external concentration (supply) of potassium mainly fluctuates, whereas the internal sensor is advantageous primarily when the demand for potassium fluctuates.” The beauty of the dual sensor is that it can deal with both types of fluctuations simultaneously.

The KdpD dual sensor has been likened to sophisticated temperature control in modern heating systems and other control schemes, but it does so without computer memory or processing power or wires or electricity, and all at the nanoscale. “It is absolutely amazing how KdpD combines dual sensors and dual controllers into a single nanometre-sized molecule,” says Gerland. “Where engineering can primarily learn from biology is on the level of system integration and miniaturisation.”

Water of life

Another industrial area in which biomimicry is making waves is water purification. Water is essential to the industrial sector – from heating, cooling, processing, cleaning and rinsing processes to essential components of manufactured products like beverages and pharmaceuticals. But if not treated correctly, it can also be a source of problems: corroding and fouling essential materials, reducing the quality of manufactured products, and even posing health risks. So, any techno­logy capable of purifying water cheaply and effectively will pique the interest of industrial leaders.

This is the exact reason Aquaporin A/S, a Danish biotech start-up, is attracting interest from the sector. “The Aquaporin Inside Membrane technology can be seen as a generic technology capable of separating water from all other compounds,” explains Aquaporin Vice President and Technical University of Denmark Associate Professor Claus Hélix-Nielsen. “We are currently focusing on making membranes for household purifiers and also treatment of industrial wastewater.”

So far, so unremarkable, but under the hood the Aquaporin technology takes its cue directly from nature. “Aquaporin molecules are a special class of proteins normally residing in cell membranes where they essentially act as very efficient selective water channels,” Hélix-Nielsen explains. “We use these proteins as building blocks in the fabrication of the membranes.”

The Aquaporin team has looked far beyond industrial applications, investigating its use to make clean drinking water for the almost 800 million people glo­bally who do not have access to potable water, and even working with NASA and the European Space Agency to improve water purification on board the International Space Station. Their membrane filter uses Aquaporin proteins to pull clean water out of urine, sweat, wastewater, condensation and other liquid sources available in space.

After recently being tested by the first Danish astronaut, the Aquaporin solution proved lighter, quicker, more robust, more energy-efficient and cheaper than the existing filtration device on the space station. A future version of the technology may even find itself aboard trips to Mars later in the century.

Article by Benjamin Skuse 


Medical solutions inspired by biology

Sharks are a useful model, both for their slick skin and for their antibodies that can be used to treat cancer.  pioneers-in-biomimetics

Industrial manufacturers are not the only ones turning to nature for inspiration. Medicine is also making advances in biomimetics. Shark skin is often used as a model due to the anti-fouling and drag-reduction properties of its structure. But that’s not all. Johannes Buchner, a professor of biotechnology at the Technical University of Munich, has begun studying the animal’s immune system.

Medical antibodies can be used to diagnose and treat cancer, but the organism quickly breaks them down. To deal with this problem, Mr. Buchner turned to nature to find robust antibodies. He needed a species distant enough from humans to have a different immune system. “500 million years separate us from the shark, and we found out that it has extremely resistant antibodies,” Buchner says.

After identifying the structures that give the shark’s antibodies their strength, the German research team was able to alter human antibodies to better resemble those of a shark.

Microscopic pumps

Jaap den Toonder, a professor at the Institute for Complex Molecular Systems at the Eindhoven University of Technology, has been working to identify natural equivalents to engines and other pumps. He has found them in muscles and, at a molecular scale, in motor proteins such as dynein. “Motor proteins are responsible for the movement of muscle and cilia – long, thin structures measuring a few micrometres in length. They are everywhere and play a crucial role in the circulation of fluids (blood, urine, perspiration, etc.) in animals and plants.”

What is the researcher aiming for? Using these cilia to reproduce the anatomy and functions of organs in the style of microcircuits, creating “organs-on-chips” that can be used as experimental models or for medical analysis. Blood and sweat typically must be able to circulate in any experiment.

“Our devices are so small that flow has to be controlled on a scale of about 10 micrometres,” den Toonder says. “Current pumps are not precise enough.” Only bio-inspired cilia seem to be able to achieve such a feat.

Article by Yann Bernardinelli @YB_SciRedac

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