‘Look deep into nature and you will understand everything better,’ said Albert Einstein. Yet modern industrial humans have rarely followed this advice. A glance around any city reveals a world of straight lines; one that relies on a huge input of fuel to keep things moving. Nature, by and large, abhors straight lines and the most important goal for any species is to use energy as efficiently as possible. To do so, living things have evolved over millions of years, perfecting ingenious structures, modes of behaviour and methods of communication.
This is significant in our modern world. Reliance on huge amounts of fuel and noisy, polluting construction methods are unsustainable. With this in mind, some researchers are turning to nature for answers. The field of biomimetics (and its cousins biomimicry and biophilia), in which scientists across the spectrum of biology, physics and chemistry attempt to mimic the natural world in order to engineer new products, is a thriving one. From those working to copy the astounding strength and stickiness of spider silk for commercial adhesives and bullet-proof vests, to those turning to slug mucus as inspiration for surgical sealants, inspiration is being drawn from every corner of the animal and plant kingdoms – though as the examples overleaf indicate, the underwater world is particularly prevalent.
Researchers at the forefront of this discipline operate via an entirely different set of principles from those engineers have pursued to date. ‘Nature is really efficient in her use of energy and use of materials, because neither of those things are available in abundance to an animal,’ says Dr William Megill, an engineer and biologist at Rhine-Waal University, who designs and builds propulsors and sensors inspired by underwater creatures. ‘When your energy source is shrimp, you’ve got to be careful about what you do. When your energy source is a nuclear power plant, you don’t care. We’re trying to replace the way that engineers typically look at problem solving, which is to throw energy and materials at it. In biology, the solutions that are typically used are information and structure.’
This energy-efficient approach to design logically means that many in the field consider it a discipline with answers for a more sustainable world. ‘When we look at what is truly sustainable, the only real model that has worked over long periods of time is the natural world,’ writes Janine Benyus, co-founder of The Biomimicry Institute.
Nevertheless, this vision isn’t easy to achieve. While scientists all around the world are busy extracting nature’s secrets, getting bio-inspired products to market is difficult. The most commercially successful biomimetic product to date is still one of the oldest. As the story goes, at some time in the 1940s, Swiss engineer George de Mestral was busy hunting in the Jura mountains when he noticed that the tiny hooks of cockle-burs were stuck to his trousers and his dog’s fur. De Mestral studied and finally duplicated the hook and loop structure of the burs and thus VELCRO® was born, a friend to children the world over.
A closer look reveals that other products inspired by nature surround us. Though most commonly known as the ‘bullet train’, the streamlined front of Japan’s Shinkansen trains was inspired by the beak of the kingfisher. The train faced the challenge of moving from low-drag open air to high-drag air in tunnels (a process which created a large amount of noise). The kingfisher – used to silently plunging into water – provided some answers. And, at the most basic level, all aeroplanes owe their debt to pioneers inspired by birds, something that’s still ongoing, albeit with a dip underwater instead. German company Lilium recently began flight-testing an all-electric air taxi which mimics the structure of manta rays.
Yet, these success stories aren’t indicative of the wider field, in which many products struggle to make it to market. Often it comes down to cost. A researcher in a lab might build a perfect nature-inspired prototype, but mass production with low-cost materials is difficult.
For some in the field, it also comes down to a fundamental difference in outlook between biomimetisists and engineers and, in the latter, an unwillingness to embrace change.
‘We really try hard to put our biomimetic ideas into industry, that’s the real challenge,’ says Megill. ‘Engineers by and large, don’t like change. I guess it’s the paradigm: If it ain’t broke don’t fix it. We just keep repeating a solution because it works, instead of backing off and saying: you know what, if I were to rethink concrete I would want to use lighter weight materials. There are so many really cool ways of making buildings today that don’t involve concrete.’
Reflecting on a career in the field and in particular, research conducted into mother of pearl – a material produced by some molluscs that, due to its structure, is 3,000 times more fracture-resistant than the mineral it is made of – Dr John Vincent also highlights this cultural difference. ‘Mother of Pearl is made up of lots of platelets, about half a micrometre thick,’ he explains. ‘The plates can move relative to each other, but they don’t have flat surfaces, they’re slightly wavy. If you’re an engineer and look at that, you think: ‘Oh god nature’s cocked up again, those should be absolutely flat.’ As a result, Vincent says that a mother of pearl-like structure has not been successfully commercialised despite its useful properties – namely an impressive resistance to breakage. ‘People are still arguing about what’s the best thing to do with it, but there is a way to do it and that’s to make a material with a certain amount of randomness in it.’
It would be unfair however to lay the blame solely at the door of engineers. Dr Christian Hamm, a bioscientist at the Alfred-Wegener Institute for Polar and Marine Research believes that scientists have a responsibility to ensure that their work is commercially viable. ‘It’s necessary for scientists to be realistic,’ he says. ‘It’s very easy to build a prototype with a lot of money.’
Hamm admits that his own team has fallen prey to this in the past when designing a bionic, folding bike inspired by the microscopic structure of plankton (which can be remarkably strong yet lightweight). The bike was created using cutting edge laser additive manufacturing methods. ‘If you wanted to sell it, it would cost about 15,000 euro,’ he says. ‘The difficult thing is to make it really efficient and to adapt it to the production process. It’s not only on the side of industry, because small and medium companies have a lot of pressure to pay wages and all that stuff.’
Nevertheless, the challenges of the modern economy aren’t preventing pioneers from taking their ideas further, or from trying to unpick some of the most complex questions nature presents – how exactly does a fish propel itself through water? How does a flock of birds interact? Why does a kangaroo not lose energy the more it jumps? – and using the answers to inspire new ideas and products. And, despite obstacles, the market size is predicted to grow. A 2016 article in the International Journal of Science and Research stated that between 2005 and 2008, the market size for products and construction projects that applied biomimetics was estimated to be above $1.5 billion. By 2025, industry analysts project that products and services in biomimicry will increase to $1 trillion in market size. In the US alone, it is expected to have a $35 billion market with over 1.6 million new jobs.
That’s not to say all products will find their way out of the lab, in fact, many won’t. But those that do make it have the potential to change the look and feel of the manmade world in a way that brings it much closer to the natural one. Most importantly of all, these products could contribute to a world in which efficient use of safe, renewable resources, rather than colossal volumes of finite fuel, becomes the norm.
FISH OUT OF WATER
Transport offers some of the clearest examples of biomimicry, with planes, trains and to some extent automobiles taking inspiration from the streamlined shapes offered. Not all have been successful. Mercedes Benz’s 2016 attempt to design a car in the shape of a box fish – a small reef fish with a cuboid, compact body – was a notorious flop, with researchers later stating that the company had misinterpreted the hydrodynamic profile of the fish, actually choosing an animal with a less streamlined body than many others. There are however many new developments in the field.
Dr Claudio Abels is a scientist at Rhine-Waal University. His research into the ability of fish to detect water flowing over their scales is the basis for an project called Fluctomation. Fish possess what’s known as a ‘lateral line system’ – a series of organs located on the head and sides of the body. Within these organs tiny ‘hairs’ sense water flow and send a signal to the brain. The fish can then adapt its behaviour accordingly. ‘The fish always tries to save energy,’ says Abels. ‘There are many fluctuations and disturbances in the water flow that it can use to do so. It can use vortices to passively bend the body for example.’
Realising that this same system could have many real-world applications, Dr Abels’ team have designed miniature sensors that feature tiny ‘hairs’. When placed in a row they mimic the lateral line system and detect the flow of air. The applications are varied, with transport one of the most obvious.
‘We could use those sensors to detect air flow around a car and trailer,’ explains head of department Dr William Megill. ‘If we want autonomous vehicles, we need to protect the trailer and vehicle from offside flows that hit it and make it lose control. We want to try and give the trailer a sense of the flow around it so then it can react by applying the brakes or whatever is needed.’
Away from the road, Abels explains that the sensors could be used to detect air flow in air conditioning units, scuba diving equipment or even human lungs. His team is currently working on methods to mass-produce the sensors and make them commercially viable.
BUMPS, LUMPS AND RIBULETS
Standard wisdom says that flat, smooth surfaces are the most streamlined and therefore best for reducing drag, but this isn’t the lesson nature teaches and several businesses are taking note. Since 2016, certain Airbus jetliners have been fitted with small ‘riblet’ patches – textured surfaces applied to the fuselages and wings – which mimic sharkskin and which the company claim reduce drag.
Lessons have also been learned from humpback whales. These giants have bumpy ridges on the front side of their flippers. While an initial source of mystery for biologists, research by scientists at Harvard in 2008 revealed that the bumps enable the whale to achieve a steeper angle between the flow of water and the face of the flipper than would otherwise be possible – something that ensures greater efficiency of movement.
And so, from whales to aeroplanes. A steep angle between an aeroplane wing and the air is desirable but, if too steep, can lead to ‘stall’ in which a lack of air flowing over the top surface causes increased drag and lost lift, a potentially dangerous situation that can result in a sudden loss of altitude. Previous experiments have shown, however, that the angle of attack of a humpback-whale flipper can be up to 40 per cent steeper than that of a smooth flipper before stall occurs.
This research led to the creation of WhalePower Corporation, a company which now licenses the rights to utilise humpback-style tubercles on various devices, particularly compressors, fans, pumps and wind turbines. In tests on wind turbines, the addition of tubercles has been shown to eliminate noise and boost annual energy production. One Canadian company now using the technology in its fans has been able to reduce the number of blades and still maintain the same airflow, lowering production and running costs.
It hasn’t been an easy road. ‘I don’t have the million gazillion dollars that everyone thought I would,’ says WhalePower president Dr Frank Fish. Turning back to aviation, he says: ‘We’re not used to seeing aeroplanes with bumps on the front edge of the wings and so from a traditional standpoint people may want to shy away.’ Nevertheless, he believes that if taken seriously, the technology could remove the need for the heavy and bulky safety equipment currently stored on plane wings and ‘make the plane lighter and thus more efficient and economical to run’.
ANT’S EYE VIEW
‘I figured out that desert ants were a good model for navigation because they are the best navigators known in the world,’ says Dr Julien Dupeyroux, a postdoctoral researcher at Delft University of Technology. Unlike other ants, which rely on chemical trails left by their companions to make it back home, desert ants use ultraviolet-detecting eyesight to find rough patterns in the world around them, while also counting their footsteps and monitoring how fast the ground streams past.
Following this example, Dupeyroux has created AntBot, a six-legged robot which can navigate autonomously in difficult terrain and which is more accurate than consumer GPS alone – the bot can get within centimetres of its destination, as opposed to metres. Just like the real thing, AntBot uses an eye designed to detect the sun’s ultraviolet light and a pair of rotating polarizing filters to determine its relative position. It also counts its steps and monitors the speed of the ground flowing past.
The robot may prove useful for exploring unfamiliar or dangerous terrain and in situations where a GPS signal is unavailable or unreliable. On a wider level, the navigation system is already being trialled in cars. ‘The biorobotics group in Marseille [where AntBot was developed] now has partnerships with PSA Group, the French car manufacturer,’ says Dupeyrouz. ‘It could also be used for the ground-robot industry in cities, for autonomous delivery services. And for drones,’ he adds, a subject that many others have their eye on. The latest drone project at the University of Cincinnati aims to mimic the sonar skills of bats to help drones navigate in the dark, dust or smoke.
What’s most exciting, according to Dupeyroux, is AntBot’s extremely low computational needs (it only requires a few pixels). ‘I’m a believer of bio-inspired models,’ he says. ‘When you consider autonomous cars, they have very big stuff on top of them, which consist of a lot of cameras with millions and millions of pixels, yet when I look into nature I figure out that very tiny insects with low computational resources can perform far better than we do now, with far less.’
Much of biomimicry focuses on the exterior surfaces or skins of plants and animals. Researchers in this space seek to understand how texture, colour and other properties can be replicated in useful ways.
One of the most well-known examples is the ‘lotus effect’, in which synthetic materials are created that mimic the self-cleaning properties of the ultra-hydrophobic lotus flower, the surface of which features tiny wax crystals which jut out and repel dirt and water. Surface finishes inspired by the plant have now been applied to paints, textiles and glass (including that covering the sensors of traffic control units on German autobahns) reducing the need for chemical detergents.
More recent lab-work has focused on colour, in particular the colour-changing properties of animals such as cuttlefish, zebra fish, octopus and chameleons, with applications from camouflage clothing to fast, efficient blood-testing in mind.
At Cambridge University, researchers have created an artificial skin that changes colour when exposed to light. Dr Andrew Salmon, a research associate, explains that the material adopts the process by which cephalopods concentrate pigments into specific locations within their cells, making them more or less transparent. To mimic these pigments, the team suspend nanoparticles of gold in solution (a nanometre is one billionth of a metre). These minuscule particles can be clumped together or ‘unclumped’. When the solution is exposed to heat or light, the particles stick together, changing the colour of the solution.
This fairly simple approach is a far cry from the mesmerising dance of the cuttlefish, but could still be useful.
Salmon’s eventual aim is to use the material for rooftops, the idea being that when it’s hot the material will be transparent and thereby reflect sunlight, keeping the building cool. When it’s cold, the material would automatically switch to black.
‘We’re working out how to make sheets of it and how to make it reliable enough to work all the time,’ he says. First step is to replace the gold particles with a less costly material. The team are trialling carbon black – the material that colours car tyres.
As long as the wound sustained isn’t too significant, all living creatures have the ability to heal – an ability with obvious benefits. Perhaps unsurprising then that scientists are attempting to copy this mechanism, with those at Penn State University once again turning to the ocean to do so – this time, to squid.
It is well known that squid have teeth inside their suckers, known as squid ring teeth (SRTs), which allow them to attach to prey. SRTs contain a protein that enables them to heal when damaged. The protein contains both soft and hard parts which enable broken proteins to fuse back together in water, while also reinforcing the structure.
The Penn State researchers have now discovered that the protein in SRTs can be used to create a hardy coating for fabric that has the ability to stick itself back together when damaged. This self-healing occurs in the presence of water, so the researchers are working on a material that could heal under normal washing conditions. Thankfully, this shouldn’t involve capturing thousands of squid. An average sized squid only contains around 100 milligrams of SRT protein, so the Penn State team have genetically engineered E. coli bacteria to grow it in the lab.
Tellingly, the research at Penn State is being funded in part by the Army Research Office and the Office of Naval Research in the US. The idea is that self-healing garments could be tailored for protection against chemical and biological warfare agents. Nevertheless, the coating could have many other uses. The researchers point to the potential for self-healing fibre-optic cables and coatings for medical devices such as meshes and biomedical implants.
BUILDINGS THAT BREATHE
‘I started looking more at building skins, and wondering why we don’t look at a building as an organism,’ says Doris Sung, a US-based architect who works with smart-materials that move in response heat. ‘If the heart is the main mechanical system, and the control of air conditioning and heating is the circulatory system, then why isn’t the building envelope much like human skin? Skin is the first line of defence so that the heart and the lungs don’t have to overwork. With the same basic idea, I kept thinking: why can’t the building envelope do that?’
Sung is one of only a few architects currently working to apply these concepts to buildings. She uses a thermal biometal that moves in response to solar energy and which can be laid out, scale-like, over a structure. As the scales move autonomously, they can shade a building in the heat and let in sunlight in darker conditions.
Across the Atlantic, Dr Cordt Zollfrank, a professor at the Technical University of Berlin is working on a similar concept. His recent work takes inspiration from the pine cone, a plant that opens and closes in response to moisture. Motivated by the fact that worldwide, the use of buildings accounts for 40 per cent of total energy consumption, around half of which is used for climate control, he believes buildings can be adapted to self-shade and self-ventilate. ‘I’ve almost spent my whole academic life looking into these materials,’ he says. ‘I’m an organic chemist by training, but did my PhD in forest sciences so I came in touch with natural materials, which normal chemists do not.’
There is still work to be done. Pine cones open and close over several hours – too slow to be useful – but Zollfrank believes his team will overcome these limitations: ‘The main aim is to make the systems faster and make them larger.’