The Gecko’s Foot: How Scientists are Taking a Leaf from Nature's Book

What is especially interesting about nanotechnology and bio-inspiration is the existence of hybrid technologies (#litres_trial_promo) – systems in which one part comes from technical nanotechnology and the other part from natural mechanisms. Our minds are attuned to an ‘animal, vegetable, mineral’ classification system and we generally assume that anything will belong to just one of these categories. One of the most dramatic discoveries of bio-inspiration is that technical components can be incorporated into natural systems.

Although cells never meet silicon chips or other electronics materials (which have only existed for 30–40 years) in nature, natural proteins can stick to silicon and other electronics materials and in doing so create structures on a much finer scale than would be possible for the technical materials alone.

Engineers make things by heating, beating and hacking them into shape; chemists make things by cooking up the ingredients; nature makes things through the DNA in the genes. The plan of every creature that exists is at some stage just a coded blueprint strung out along the double helix of DNA (#litres_trial_promo). Nature’s way is by far the most subtle, accurate and fine scaled. It can be seen as a combination of engineering and chemistry. DNA is a chemical but it also has architecture – the double helix – and the substances DNA makes – proteins – also have architecture. They are both chemicals and pieces of nanoengineering.

To exploit DNA’s design potential, bio-inspirationists use hybrid techniques of genetic engineering and silicon-chip fabrication. This may trouble some people – but nature does not recognize the division between organic and inorganic: gorgeous inorganic mineral shell structures are produced under organic control. The rigid organic/inorganic divide is a product of the human mind, more specifically that of chemists who have put the labels ‘Organic’ and ‘Inorganic’ over the doors of departments which used to have very little to do with each other.

When I put it to Mehmet Sarikaya, the passionate advocate of this new hybrid technology, that some would see a Frankenstein element in it, he said: ‘There will be more good happening than bad because human beings are fundamentally good people. What’s at the back of this scientist’s mind is: Can I have an impact on the early detection of cancer? Can I have an impact on assembling nanofibres for new nano-molecular devices? That’s what we have in mind, that’s why we work.’

Although bio-inspiration is still largely unfamiliar to a wide public, nanotechnology has already attained a certain notoriety. The idea is abroad that there is something inherently dangerous in the nanorealm. Michael Crichton’s bestseller Prey (#litres_trial_promo) (2002) imagines self-replicating nanorobots escaping from human control, learning rapidly and becoming ruthless predators. What lies behind this fantasy and does it have any credibility?

We have always lived in a nanoworld – our bodies and those of all living things are composed of biological nanomachines, and the dust in the air, pollen grains, smoke from all forms of combustion, contain nanoparticles – but like M. Jourdain in Molière’s Le Bourgeois Gentilhomme, who was astonished to discover that he had been speaking prose all his life, we have only just woken up to the fact. And this has caused panic in some quarters. The idea behind Prey came from Eric Drexler’s Engines of Creation (#litres_trial_promo) (1986), which first put nanotechnology into the public arena. Drexler suggested that nano-technology would spawn self-replicating systems that might get out of control, thus swamping the world with a ‘grey goo’ of synthetic nanomaterial.

The idea of ‘grey goo’ took on a life of its own; it was resurrected in 2003 by Prince Charles in a speech warning of the dangers of nano-technology (#litres_trial_promo). But, in 2004, Drexler set the record straight, in an article co-written with Chris Phoenix of the Centre for Responsible Nanotechnology, saying:

Nanotechnology-based fabrication systems can be thoroughly non-biological and safe: such systems need have no ability to move about, use natural resources, or undergo incremental mutation. Moreover, self-replication is unnecessary; the development and use of highly productive systems of nanomachinery (nanofactories) need not involve the construction of autonomous self-replicating nanomachines.

Of course, the nanotechniques of bio-inspiration are biological but, when you look at what these techniques are, you will see that there is no way that their products could reproduce themselves and get out of control.

Even if nanotechnology is not going to swamp the world, many people remain concerned about some aspects of it. In 2004, the Royal Society and the Royal Academy of Engineering published a report on its benefits and possible dangers (#litres_trial_promo). The report stressed that while it would be wise to be wary of ingesting nanoparticles and releasing them to the environment without tests to ascertain what effects these substances can have, nanostructures are a different matter. Nanoparticles are potentially dangerous on two counts: being so small they can enter cells by routes forbidden to larger particles and because they have such a large surface area relative to their volume their chemical and electrical properties are enhanced, which raises the possibility that they could trigger damaging reactions within the cell. There is no reason to fear solid objects structured at the nanolevel: the world is full of solid nanostructures. All living things, including us, are necessarily nanostructured – made from atoms which have to be assembled into nanostructures before they can make up anything large enough to be seen.

The possibility of a hysterical reaction to things nano really came home to me when I visited the glassmakers Pilkington in St Helens, Merseyside, to discuss Activ™, their new self-cleaning glass, described in Chapter 2. Activ glass has a very thin coating on the surface that gives it self-cleaning properties. This coating is less than 20 nm thick. Kevin Sanderson, one of Activ’s inventors, told me that they had received worried telephone calls asking, ‘Are these nanoparticles on my Activ glass window going to fly off the surface and do me harm?’ In fact, the nanolayer is bonded very strongly to the glass underneath, it is harder than glass and will last as long as the window does.

As for nanoparticles, there have always been and always will be nanoparticles in the environment: they are called dust. All forms of combustion produce huge clouds of them. The air in the London Underground is full of nanoparticles and some of them may even be carbon nanotubes, the most famous nanoparticle, created by the action of electric sparks from the live rails. It seems likely that the concern about nanoparticles being added to sunscreens and cosmetics will lead to new research on our total exposure to nanoparticles – from car exhausts and the Underground, to bonfires and barbecues.

Every new technology creates fear and resistance, but as far as it is known at all, bio-inspiration has had a good press to date. It has an eco-friendly feel to it, unlike the more hard-edged nanotechnology; but once its connection to nanotechnology becomes known – that bio-inspiration is mostly nanoscale technology – it will be damned by some through association. So it is important to stress that there is nothing wrong with nanotechnology per se.

But if nanotechnology induces fear in some people, in science it is also a buzzword: play the nanocard and you unlock the funders’ purse strings. As a result, a lot of people have suddenly discovered that, in reality, they are doing nanotechnology. Physicist Andre Geim tells of engineers ‘who never make anything smaller than 1 metre in diameter and now they’re doing nanotechnology because they can position their things to within 1 nanometre accuracy!’ As Geim says, ‘Adam and Eve were nanotechnologists, they created everything from sperm, from DNA!’

Bio-inspiration arrives at a time when there is organicism in the air, especially with regard to architecture and design. The theme of Expo 2005 (#litres_trial_promo), held in Aichi, Japan, from March to September 2005, was ‘Nature’s Wisdom’. Organicism is abroad in both the Zeitgeist of general culture and in materials science and there are connections between large-scale bio-inspired architecture and bio-inspired materials. Many architects want to design smart buildings and to use the new bio-inspired materials. The first really commercial application of bio-inspiration is in paint for the exteriors of buildings, using the Lotus-Effect, closely followed by Pilkington’s self-cleaning Activ™ glass. And if other bio-inspired materials are not yet ready, there is no law against including organic curves in the shape of a building.

In September 2003, the Zoomorphic exhibition at the Victoria and Albert Museum (#litres_trial_promo) recognized this new tendency in architecture, with structures based on many creatures, from sea sponges to dinosaurs. The archetypal figure is the Spanish engineer and architect Santiago Calatrava, creator of the Athens Olympic Stadium. Calatrava’s buildings and bridges exhibit creaturely gestures rather than mimicking specific creatures: there are moth-like antennae, forest canopy train-shed roofs, reptilian snouts, a whale’s tail (or bird of prey’s wings). After the turbulent history of architectural styles since the early 20th-century modernist revolution, organic architecture seems an attractive option. It uses the same materials as hi-tech architecture, and both organic and hi-tech architectures have their roots in geometry. Indeed, the key to all bio-inspiration is that nature and human artefacts are acted upon by the same forces and they occupy the same three-dimensional world. And this is why similar solutions are possible in each.

Alongside the architecture, in cars such as the Vauxhall Tigra, Ford Ka, Volkswagen New Beetle and the latest Nissan Micra, recent car design has also shown itself leaning towards organicism. The idea behind these cars is to be expressive: they sit unusually on the road, with the tail up, and the headlights styled as eyes, giving the impression of a face. These are cars whose moods you can read. In the case of the Vauxhall Tigra, the first of the breed, there is a resemblance to the warning display of an eyed hawkmoth – which is appropriate, because the hawkmoth displays large eye patterns on its wings, trying to look like a much larger and fiercer creature; similarly, the Tigra is a tame little Corsa dressed up to be racy. Whether or not there is a functional reason for such large-scale organic structures (and often there is not) they belong to the new worldview that bio-inspiration has ushered in.

While writing this book, I have found myself watching insects in the garden far more closely. In fact, I wonder if I ever really noticed them before, other than on the increasingly rare occasions that a butterfly flew in. A sudden flurry in the corner of my eye and a garden spider is binding an already unrecognizable insect. Hoverflies punctuate the air around the Coreopsis. Two cabbage whites lurch across the garden in a mating dance. I realize that one of the reasons I used to be impervious to this micro-choreography is that it all seemed so impenetrable. How on earth did they do it? But, increasingly, we know, or if not, we know how we are going to know in a few years’ time. Welcome to an Aladdin’s cave of bio-inspired materials and devices.

CHAPTER TWO The Great Sacred Lotus Cleans Up (#ulink_fe77cfea-352a-54eb-9455-46d02a1e4b00)

Though buried deep

In the slime of the pool,

Unstained and untouched

You come forth to the world

Glorious in beauty,

Pure and serene:

Yet in your innocence

Oft you deceive us

Transforming the dew

On your life-giving leaves Into sparkling gems!

GONNOSKé KOMAI, ‘To the Lotus-Bloom (#litres_trial_promo)’

‘Nooks and crannies harbour dirt,’ we have always been told: a piece of folk wisdom scientists would not have bothered to dispute until some 15 years ago. But the self-cleaning powers of the sacred lotus plant – recognized and sanctified thousands of years ago in the East – have turned this on its head. The lotus’s secret is that its surface is rough at the micro- and nanolevels. It is almost embarrassing that such an elemental discovery should have waited so long to be made, but it has opened up for human use a new field of self-cleaning surfaces, utilizing the Lotus-Effect

.

Water skitters off a lotus leaf like drops of mercury – it doesn’t spread and the globules it forms are highly spherical. So water doesn’t last long on a lotus leaf. As for dirt, it seems to have a greater affinity for water than for the leaf so when it rains it is simply washed off.

There is a school of thought that science has still to rediscover the greater wisdom of the Ancients. In the case of the lotus, they are right. In ancient Eastern cultures, the lotus’s immaculate emergence from muddy water was more than noticed: the plant became a symbol of the triumph of enlightenment over the dross of earthly life. So deeply does the lotus pervade Indian, Chinese and Japanese consciousness that the name is a byword for, and a guarantor of, purity. The most famous Buddhist chant, Om mani padme hum, translates as ‘Behold! The jewel in the lotus’, and the classic Buddhist texts are known collectively as the Threefold Lotus Sutra (#litres_trial_promo). The quest for spiritual cleanliness that runs through Buddhism derives from the lotus’s example, so much so that images of cleaning recur in the texts:

The Law is like water that washes off dirt. As a well, a pond, a stream, a river, a valley stream, a ditch, or a great sea, each alike effectively washes off all kinds of dirt, so the law-water effectively washes off the dirt of all delusions of living beings.

Innumerable Meaning Sutra

While researching this book, I experienced my own lotus epiphany. I had flown from San Francisco to Seattle, and was en route from the airport to the University of Washington campus. It was a long day, my trip was almost at an end and I was tired and anxious. I had to change buses in the middle of Seattle’s downtown subway system. I emerged in the middle of Chinatown and walked into the nearest café for a bite to eat. In the middle of the counter, staring up at me, were lotus cakes. I ate one – it tasted rather like chestnut – and a Proustian madeleine feeling came over me, although this was not for the recollection of time past but a kind of blessing on the future of my enterprise. I had risen from the underworld of the subway system, in which the route to enlightenment – Washington University campus – was temporarily lost. The notion of sweetness

arising from dross is such a powerful one that once you know of the lotus you cannot help but refer to it: hence its omnipresence in East and South Asian cultures.

In the West, appreciation of the lotus is more aesthetic than spiritual: ‘No more stately plant adorns our gardens than lotuses (#litres_trial_promo),’ is a typical statement from an early 20th-century horticultural book on the water lilies.

(#litres_trial_promo) Concerning the flowers, the book goes on: ‘These great blossoms are among the noblest products of the vegetable world. They fairly glow in the morning sunlight.’ With flowers 20–30 cm across, some of the leaves sit on the water, as water lily leaves do, and some stand 1 m from the surface. The water that collects on them is tossed back into the lake by the wind. In size they are dwarfed by the largest water lily, the Victoria regia from the Amazon, which was first brought to flower in England by Joseph Paxton in 1849, but the grace conferred by the lotus’s exceptional purity more than compensates for that. (Incidentally, Victoria regia also has a role in the development of bio-inspiration; Paxton, as the engineer of the Crystal Palace in 1851, was much influenced by its structure; see Chapter 9.)

I was not sure whether I had ever seen a lotus before I became interested in the Lotus-Effect: water lilies of course, but had some of these been lotuses? I went to the Botanic Gardens at Kew, London, to find out for myself. Lotus plants die down every year and in cultivation are replanted from the runners that spread from the rhizomes rooted in the mud. At Kew in April they had plants of a variety of the American lotus, ‘Perry’s Giant Sunburst’, growing in tanks next to water lilies. Although it had a name redolent of out-of-town garden centres, nevertheless it was a real lotus: the leaves had that bluish bloom you see on some cabbage leaves. Dropping water on the lotus leaves was like dropping mercury on the table. The water drops gleamed with internal reflection and skittered around like quicksilver (fig. 2.1).

The Lotus-Effect’s discoverer, Professor Wilhelm Barthlott, Director of the Nees-Institute for Biodiversity at Bonn, Germany, is unusual in pursuing parallel careers as a research botanist and as a patent-holding industrial inventor working closely with many industrial partners. ‘Technology transfer’ is a buzz phrase in universities these days, as governments try to kickstart economic growth by applying university expertise to the commercial world. The Lotus-Effect is a model of how it should be done.

Wilhelm Barthlott had no intention of becoming a technologist. He is a benign, avuncular and energetic man with bristling bottlebrush hair and a moustache that perhaps evoke some of plants he encounters. He has made a particular study of cacti and his interest in biodiversity stemmed from visits to Madagascar, where many of the plants are unique to the island. As often happens in life, Barthlott found the Lotus-Effect when he was looking for something else. Evolution was his obsession and in those days – before the emergence of molecular biology in the early 1960s – evolutionary

relationships were studied purely by comparing the anatomy of creatures, especially their micro-anatomy: pollen grains for example. So Barthlott spent a lot of time at the microscope.

But then the scanning electron microscope (SEM) arrived that was to transform his work and would ultimately lead to his discovery of the Lotus-Effect. The SEM, which came onto the market in 1965, uses television-style scanning to produce richly contoured images with the appearance of 3-D.

With the SEM, a wonderland of fine structure, as detailed as any architect’s fantasy, came into view. The surface of plants is a strange other-worldly terrain (#litres_trial_promo). The outer surface does not consist of living cells but a non-living shell, the cuticle, covered in layers of waxes of varied composition. Sometimes the waxes are deposited on the surface in bizarre shapes (fig. 2.2). Through the microscope these structures often look more like animals than plants: Virola surinamensis seems to have miniature starfish nestling on a bed of waxy bobbles; the surface of Colletia cruciata resembles nothing so much as Anthony Gormley clay figurines, lolling about on the leaf; and Williamodendron quadrilocellatum has little piles of wax rings that could be a new form of pasta. Then there are miraculous architectural sweeps – the seed coat of Lychnis viscaria has plates that lock together like the tessellations of an Escher drawing. (Chapter 9 explores how structures like this have become important sources of inspiration for contemporary architects.) But most plants have bobbles like miniature topiary yew trees, with a frosting of waxy crystals on top.

(#litres_trial_promo)

For a while, Barthlott was engrossed in the sheer beauty of these structures, but then something unexpected emerged. Specimens must be cleaned to be looked at in detail – at very high levels of magnification, contaminants can ruin the picture. But, in 1974, Barthlott realized that certain plants never seemed to need cleaning (#litres_trial_promo) and that these, under the microscope, were always the ones with the roughest surfaces.

This was the beginning of a trail that was to take Barthlott far from his comparative studies of the structure of plants (although he is still highly productive in this field), into the world of technical production of a new invention. The full impact of the self-cleaning effect crept up on Barthlott over a long period: the early work, he says, was ‘purely descriptive, without measurements’. He believed he had discovered something important in botany but ‘it never occurred to me that it could be something new to physicists and materials scientists’.