What is Biomimetics
What is Biomimetics?
The following is an extract from a radio interview originally broadcast on New Zealand Public Radio. Julian Vincent is interviewed by Alison Parr.
Alison Parr (AP): You may think that Velcro and the Eiffel Tower have nothing to do with each other. But the designers of both of them have been inspired by the natural world. The two are examples of what's known as "biomimicry" - taking good designs from nature. In their struggle to survive, plants and animals have evolved solutions to the same kind of problems that scientists and engineers confront today. And so biologists, designers and engineers increasingly are working together, using those solutions from the natural world. One biologist who's working in this area is Professor Julian Vincent of the University of Bath in England. He stresses that biomimicry is an approach to design that has very practical applications.
Julian Vincent (JV): A number of times we have people from industry to talk to. They come up with a particular product that they'd like to develop or they have a particular problem. I then ask myself whereabouts in nature do we find a similar sort of mechanism or a mechanism with similar characteristics. For instance someone wants a new way of packaging liquid for a new type of food. This is just what apples do. Their basic design is that they contain food which is attractive to animals which want to come and eat them and therefore distribute the seeds. They contain the liquid in lots of tiny little cells so that an apple is 97% liquid and yet it's drip free. This is a super way of putting a meal together so that you've got something that's thirst-quenching but you can put it in your pocket without having to wrap it up in plastic. Having made that sort of analogy you then ask what are the problems involved in designing something like this. Has nature done anything in the design which we wouldn't do at present? If nature has, then you realise that it's solved a problem that you hadn't thought of. Maybe you should have a closer look at it and see how nature has solved that problem.
AP: So the idea is that because of having to solve the problems of survival over a long period of time, plants and animals have solved design problems. You've written about organisms optimising functions. What does optimising mean in this sense?
JV: The same as an engineer means. For example a tree has to grow as tall as possible to reach the light, so it wants to be as thin as possible so that it uses as little wood as possible and use it in increasing its height. But unfortunately it's then likely to bend in the middle and collapse. So it has to spread the material around the stem to increase its diameter - in the early stages with more around the base than further up, making the tree appear tapered - and it also has to put some of the energy into gluing everything together. Thus it has to partition its energy into controlling shape, making cellulose and lignin so that with the minimum amount of material it can get as tall as possible and shade out all the opposition. It has to balance all these different functions, which is optimisation. An engineer has to do the same. If you want to make a car, you want it as light as possible so that it doesn't use too much petrol getting around, but it has to have resistance to damage so that it doesn't fall apart if you hit something in it and you don't get injured.
AP: Applying the concept of optimising functions in nature to looking for design solutions in biology - does this simply mean you copy nature? Or is that not how biomimicry works?
JV: I've been trying to lay down some ground rules because I thought it would be a help if I could understand what I thought I was doing. I could then take one of our problems with our industrialists and be able to have a little check list of things I had to do in order to be sure that I had arrived at a reasonably correct answer. When you look at a natural system you look at the balancing requirements that the system or organism has got, and the optimisations that it's made. Then you have a look at the question that the engineer has asked you and see what are the different requirements of that problem. You'll usually find that the balance in requirements is different, so that the optimisations are different. So you have to understand the natural system and see where the balance occurs. Then you can see what it is you have to adjust so that you can make something that is going to work at its best in the engineering environment.
AP: So simply copying nature in terms of, for example, mimicking the structure of birds' wings..
JV: ...is disaster. Birds' wings is a lovely example, because so many of the early aviators actually did copy birds' wings. The classic story is Daedalus and Icarus, who showed that if you copy a bird's wing and make a mistake, such as using a low melting-point wax, that's it! Just sticking feathers into wax isn't good enough.
AP: So what's the next step? If we want to fly, we can see that there are some things in biology around us that could be useful in terms of designing something, but how do we then make the next step?
JV: It really is very important to understand the nature of the problem from the engineering point of view and the nature of the answer in the natural system. For instance with birds the bigger you get, the more energy per unit weight you need to be able to fly, so you find that the really big birds such as the albatross and the vulture don't flap their wings very much. In other words, if you get very big, flapping your wings may not be an option for providing propulsion because the amount of muscle required is too great. If you get even bigger than that you get to the sort of things that man was trying to make in the early days such as Leonardo da Vinci's design showing a man in a huge wooden frame trying to flap his "wings". If he'd looked at the largest birds and realised that they couldn't flap their wings very much he would have realised that in a much larger structure you can only use the wings in a fixed position. You need far, far too much power to flap the things up and down to get propulsion. Man made a mistake in not defining the problem well enough and not realising the limitations of size. The problem in flight then becomes having fixed wings and getting control with them. That was the big step forward that the Wright brothers made. But the other thing is that you must have the means of propulsion separate. That's why some of the early attempts at flight by Lillienthal and others were done purely with gliders, because there was no engine which was sufficiently powerful yet light.
AP: So are there ways of using natural design without copying the features exactly? That you can use them in the abstract, almost?
JV: I think one would be ill advised to copy the features exactly, partly because nature is so incredibly complex, but also it has totally different requirements. Most natural systems you see are full of living cells. The bird has bones in the wing which are living, so it's got all sorts of structures within the wing which you wouldn't want to put in an ordinary aircraft. The nature of the problem is therefore immediately very different. One example where it seems pointless to copy nature is silk. Man has been trying to do this for about 3000 years. With the development of biotechnology, we can analyse DNA from an animal or plant and use that material in a single- celled organism to make a variety of specialist chemicals such as hormones and enzymes. A number of groups of researchers, especially in the USA, have been trying to use this technology to produce silk. It's very difficult to do this, because silk is a long fibre with lots of repeating sequences of amino acids. The standard technique for unravelling the sequence in which these amino acids occur in a protein is to break the DNA into shorter pieces which can be handled more easily, work out the order in which the chemicals (bases) which code for the amino acids are arranged, and then string the bits of DNA sequence together by looking for overlapping zones on the shorter pieces. But if the sequence of amino acids is very orderly and repeating, it's difficult to know where you are in the sequence. It's all a bit like doing the blue sky part of a jigsaw puzzle. There's not much to distinguish one piece from another, so there are few clues available for where each might fit. This means that there are huge problems in defining the DNA to make the material. But we can make excellent fibres already. Nylon and Kevlar are very silk-like in many ways and have superb mechanical properties. What our current silk technologists should really be doing is looking at the way the spider makes the silk, picking up ideas from the way that it manages to give the silk such superb mechanical properties (it's very strong and excellent at absorbing impact loads, which is the sort of property you might want in a climbing rope or a bullet-proof vest), working out how those properties are designed into the silk, and designing those properties into Kevlar, which is a material which we can make already with much simpler technology and therefore far cheaper and in far greater amounts.
AP: So it's redundant to try to copy nature if we can do it better and in easier ways.
JV: I think a tame spider is much better.
AP: You've written, too, about inspiration which in these terms I find and interesting sort of concept. Could you give us some examples of where inspiration takes ideas from the way that biology designs things that we can use.
JV: What you need is a very open mind and the ability to jump from one concept to another and be able to extract the nub of the idea. There are many examples. One of the nicest ones is the Eiffel Tower. It's a superb structure looking a bit like a plant stem in the way it's curved. All the smaller and smaller struts look as if they are taking the forces smoothly into the ground in just the right place. The basic concept of the Tower was inspired by some work which started 40 years previously in Switzerland. Hermann von Meyer, a professor of anatomy at Zurich, started looking at the bony structures inside the head of the femur, where it inserts at the hip joint. Because this bone sticks out to the side, taking loads off-centre, the solid shaft of the bone divides up when it comes close to the joint making lots of little fingers of bone which travel across the space within the femoral head, arranging themselves along the lines of force which are generated within the structure when the bone is taking its normal loads when you stand. Von Meyer described the shapes but it was left to the mathematician and engineer, Karl Cullman, to show that the bone is arranged along the load bearing directions and that this is one of the most efficient ways of taking the off-centre forces from the hip into the long bones of the leg. It's these basic concepts of building along the lines of force which are used in the Eiffel Tower.
AP: Velcro is another material which was inspired by nature. Tell us about Velcro.
JV: Georges de Mestral, a Swiss inventor, had a rather large and hairy dog which used to run through grass where there were burdock plants which have seeds covered in tiny hooks. Mestral got fed up with these burrs getting caught in his dog's fur because they stuck in so well and were so difficult to remove. It occurred to him that this would be a good way of joining two fabrics together - hence Velcro. This is made with two components. One of them has larger plastic loops which have been cut to one side making a series of hooks. On the other component there is a feltwork of fibres into which the hooks can catch. But there is a problem. Velcro makes a noise when you rip it apart, and modern soldiers' uniforms have lots of Velcro as fasteners. Fatal if you are a sniper! We have been asked to invent silent Velcro.
AP: So you can undress quietly! (giggle . . ) That's fascinating. You've also written about the glass roof of the Crystal Palace.
JV: It's a building I would love to have seen. Unfortunately it was burned down in 1938. It was built in Hyde Park in London for the Great Exhibition of1851, designed by Joseph Paxton. He was a gardener,who grew exotic plants. One of the plants he knew was a large water lily called Victoria amazonica. This has leaves a meter or more across with curled up edges so that they float. He had a look at the underside and saw all the beautiful ribbing which was supporting this huge area. The ribbing stiffens the membrane, which suggested a good way of making a light but stiff roof which could span a large gap. He started by building a greenhouse at Chatsworth House just south of Sheffield, where he was employed. That was very successful. Then he entered the competition for the Crystal Palace with the same design. Paxton had no training in architecture or engineering. Yet he won the competition to make one of the most prestigious buildings of the Victorian era.
AP: And obviously it worked. That is almost, getting back to what we were talking about before, an exact copy of nature.
JV: It stood for 80 years, and even then was burned down. It didn't fall down under its own weight. Brilliant.
AP: So what's the future for biomimicry? Where are we likely to go with it in the next century?
JV: Gosh . . .
AP: Just a small question!
JV: Yes. Where's the crystal ball? It has been said that the next century will be the century of materials. If you go back through history and prehistory you have the Stone Age and the Bronze Age and the Iron Age . . . all these "Ages" are named after materials. At the time, those materials represented the equivalent of space technology. They were the most advanced materials available at the time, and they were the materials which could give you an advantage over other people. You could say that history is driven by the technology of materials, which allows you to make artifacts and machines which allow our technology to advance. For that sort of reason it has been said that since we are now beginning to understand materials at the molecular level and can make materials from the molecule upwards (nanofabrication), the next century will be the age of materials. We will be able to produce some of those materials with such a fine degree of control that instead of having to make something bigger and more massive in order for it to work we'll be able to make it the same size but under much more controlled conditions and get a better performance out of it by more care.
AP: And what are the likely uses of this? In terms of our practical day-to-day lives?
JV: I doubt if you'll notice very much. Other than that you can do more and more with less and less. Part of this depends on the imagination of the people who are running industry, actually. About ten years ago one of our institutes in the UK had a wish list for industries to fill in, asking them what they wanted to happen in the future. Almost all the answers could be paraphrased as "We'd like 10% more of most things". They couldn't actually come up with any new ideas. My suspicion is that you won't see very much change on the outside but you'll find that everything seems to work better or last longer or is cheaper.
AP: I wonder whether biomimicry is something which has been around for a long time, but it's advancing now because of modern science and technology. Is that a fair observation, do you think?
JV: There are more scientists alive today than have ever lived before. So you can't fail but have science advance more quickly. But just as man has wanted to fly for thousands of years, so people go on having the same ideas. Human nature doesn't change and human aspirations don't change. It's simply the means of achieving them that advances. The Chinese wanted to make artificial silk 3000 years ago, Leonardo da Vinci was wanting to fly 400 years ago . . . The most recent semi-historical reference I have found refers to Jack Steven in the US Air Force in the 50s. They had a meeting at the large research establishment at Wright-Patterson airbase in Dayton Ohio, and invented the word "bionics" which he defined as copying nature and taking ideas from nature. Biomimetics, which is what we call what we do, is another American neologism. We picked it up in 1988 and have run with the concept ever since. It's based upon understanding the way in which natural materials are put together, so we couldn't really say that what we are doing is terribly new, but we are able to apply all sorts of concepts of new technologies, and manipulate things at the molecular scale. We can now design a molecule on a computer. We don't have to go anywhere near a chemistry bench. The same thing is starting to happen with materials. You don't have physically to put bits of things together in order to be able to design them and understand the way they work. You're going to end up being able to design new materials at arm's length and have them just crystallise out of solution and know exactly the way in which they are going to perform.
AP: Thank you very much for that insight into the future, and the way in which the evolution of nature can help us to realise it.
