Skip to main content

The Nanotechnology Myth – Brian Clegg

Imagine an army of self-replicating robots, each invisibly small, endlessly reproducing, forming a grey mass that swamps the world, and destroys its resources. This was the premise of Michael Crichton’s thriller, Prey, but the concept of using invisibly small technology is not just science fiction. This so-called ‘grey goo’ scenario is fantasy (grey goo because the nanobots are too small to be seen individually, and would collectively appear as a viscous, self-moving grey liquid). But nanotechnology is real and has a huge potential.
Until recently, that prefix ‘nano’ was an unfamiliar one. At the 11th Conférence Générale des Poids es Mesures in 1960 a faceless committee defined the SI (Système International) units. As well as agreeing standards of measurement like the meter, the kilogram and the second, the conference developed a range of prefixes for bigger and smaller units from tera (multiply by 1,000,000,000,000) to pico (divide by 1,000,000,000,000). The penultimate prefix was nano, (divide by 1,000,000,000), derived from nanos, the Greek word for a dwarf. One billionth, a truly tiny scale.
Twenty-six years later, American author K. Eric Drexler combined “nano” with “technology” in his book Engines of Creation. Although Drexler outlined a wide range of possibilities for products smaller than a microbe, the majority of the book focuses on molecular manufacturing, using nanomachines to assemble objects at the molecular level, a concept first suggested by physicist Richard Feynman. A single assembler working at this scale would take thousands of years to achieve anything –assembly would require trillions of nanomachines. Drexler speculated that this would require nanomachines that could replicate like a biological creature, leading to the vision of grey goo and Crichton’s Prey.
Real nanotechnology does not involve anything so complex as an assembler. One very limited form of nanotechnology is already widely used – nanoparticles. Substances reduced to particles on this scale have a very different physical behaviour to normal materials. The most common use of nanotechnology currently is sunscreens, where nanoparticles of zinc oxide or titanium dioxide are used to protect us from the sun’s rays, allowing visible light to pass through, but blocking harmful ultraviolet. In fact we have used nanoparticles unwittingly for centuries in some of the pigments used in pottery glazing.
A more recent development is to use nanotechnology in the form of films of material that are around a nanometre in thickness. We’ve seen this in the lab with graphene, the amazing new form of carbon developed at the University of Manchester, which looks to have huge potential, but nano-coatings are already employed in the real world, protecting everything from mobile phones to footwear from liquids.
Being nanotechnology makes all the difference to the protective films produced by UK manufacturer P2i, based on research originally undertaken at Durham University. Their incredible thinness makes them ideal for this purpose because the polymer coating is not noticeable to the user –visibly or to the touch – and can be used to treat an electronic device inside and out or to cling to the fibres of clothing and footwear. The coating is applied using plasma in a vacuum chamber, bonding it to the surface, as this video demonstrates:
A little further down the line are nanotubes and fibres. Often made of carbon, these molecular filaments are grown rather than constructed and have the capability both to provide super-strong materials (as an extension of the current cruder carbon fibres) and incredibly thin conductors for future generations of electronics. Semi-conducting nanotubes have already been built into (otherwise) impossibly small transistors, while carbon nanotubes could make one of the more remarkable speculations of science fiction a reality.
Writer Arthur C. Clarke conceived of a space elevator, a 100,000 kilometre cable stretching into space that could haul satellites and space craft out beyond the Earth’s gravity without the need for expensive and dangerous rocketry. Bradley Edwards, working for the NASA Institute of Advanced Concepts commented in
Nanotubes (image from NASA)
2002: “[With nanotubes] I’m convinced that the space elevator is practical and doable. In 12 years, we could be launching tons of payload every three days, at just a little over a couple hundred dollars a pound.” Clearly his timescales were way out – but the concept is still amazing.
Today’s practical applications of nanotechnology derive largely from the special properties of small assemblies of atoms, but nanotechnology has one other incredible trick up its sleeve: quantum theory. At the scale of an atom, physics operates by rules that are entirely different to the familiar world. The counter-intuitive nature of quantum behaviour, from single particle interference to tunnelling opens up new possibilities for the technology of the very small.
Perhaps the best example of nanotechnology showing the promise of quantum effects is plasmonics. Something remarkable happens if, for example, light is shone on a gold foil peppered with millions of nanoholes. It seems reasonable that only a tiny fraction of the light hitting the foil would pass through these negligible punctures, but in fact they act like funnels, channelling all the light that hits the foil through the sub-microscopic apertures. This bizarre phenomenon results from the interaction between the light and plasmons, waves in the two dimensional ocean of electrons in the metal.
The potential applications of plasmonics are dramatic. Not only the more obvious optical ones – perfect lenses and superfast computers that use light (photonics) rather than electrons to function – but also in the medical sphere to support diagnostics, by detecting particular molecules, and in drug delivery. Naomi Halas of Rice University in Texas envisions implanting tiny cylinders containing billions of plasmonic spheres, each carrying a minuscule dose of insulin. Infra red light, shone from outside the body, could trigger an exact release of the required dose. ‘Basically, people could wear a pancreas on their arm,’ said Halas.
Nanotechnology may be scary in fiction, but away from the mythology it has an awful lot to offer.

Comments

Popular posts from this blog

The Great Silence – Milan Cirkovic ****

The great 20th century physicist Enrico Fermi didn’t say a lot about extraterrestrial life, but his one utterance on the subject has gone down in legend. He said ‘Where is everybody?’ Given the enormous size and age of the universe, and the basic Copernican principle that there’s nothing special about planet Earth, space should be teeming with aliens. Yet we see no evidence of them. That, in a nutshell, is Fermi’s paradox.

Not everyone agrees that Fermi’s paradox is a paradox. To some people, it’s far from obvious that ‘space should be teeming with aliens’, while UFO believers would scoff at the suggestion that ‘we see no evidence of them’. Even people who accept that both statements are true – including  a lot of professional scientists – don’t always lose sleep over Fermi’s paradox. That’s something that makes Milan Cirkovic see red, because he takes it very seriously indeed. In his own words, ‘it is the most complex multidisciplinary problem in contemporary science’.

He points out th…

The Order of Time - Carlo Rovelli ***

There's good news and bad news. The good news is that The Order of Time does what A Brief History of Timeseemed to promise but didn't cover: it attempts to explore what time itself is. The bad news is that Carlo Rovelli does this in such a flowery and hand-waving fashion that, though the reader may get a brief feeling that they understand what he's writing about, any understanding rapidly disappears like the scent of a passing flower (the style is catching).

It doesn't help either that the book is in translation so some scientific terms are mangled, or that Rovelli has a habit of self-contradiction. Time and again (pun intended) he tells us time doesn't exist, then makes use of it. For example, at one point within a page of telling us of time's absence Rovelli writes of events that have duration and a 'when' - both meaningless terms without time. At one point he speaks of a world without time, elsewhere he says 'Time and space are real phenomena.'…

The Happy Brain - Dean Burnett ****

This book was sitting on my desk for some time, and every time I saw it, I read the title as 'The Happy Brian'. The pleasure this gave me was one aspect of the science of happiness that Dean Burnett does not cover in this engaging book.

Burnett's writing style is breezy and sometimes (particularly in footnotes) verging on the whimsical. His approach works best in the parts of the narrative where he is interviewing everyone from Charlotte Church to a stand-up comedian and various professors on aspects of happiness. We get to see the relevance of home and familiarity, other people, love (and sex), humour and more, always tying the observations back to the brain.

In a way, Burnett sets himself up to fail, pointing out fairly early on that everything is far too complex in the brain to really pin down the causes of something as diffuse as happiness. He starts off with the idea of cheekily trying to get time on an MRI scanner to study what his own brain does when he's happy, b…