Category: General

Another draft nano-taxonomy

It’s clear to most people that the term nanotechnology is almost impossibly broad, and that to be useful it needs to be broken up into subcategories. In the past I’ve distinguished between incremental nanotechnology, evolutionary nanotechnology and radical nanotechnology, on the basis of the degree of discontinuity with existing technologies. I’ve been thinking again about classifications, in the context of the EPSRC review of nanotechnology research in the UK; here one of the things we want to be able to do is to be able to classify the research that’s currently going on. In this way it will be easier to identify gaps and weaknesses. Here’s an attempt at providing such a classification. This is based partly on the classification that EPSRC developed last time it reviewed its nanotechnology portfolio, 5 years ago, and it also takes into account the discussion we had at our first meeting and a resulting draft from the EPSRC program manager, but I’ve re-ordered it in what I think is a logical way and tried to provide generic definitions for the sub-headings. Most pieces of research would, of course, fit into more than one category.

Enabling science and technology
1. Nanofabrication
Methods for making materials, devices and structures with dimensions less than 100 nm.
2. Nanocharacterisation and nanometrology
Novel techniques for characterisation, measurement and process control for dimensions less than 100 nm.
3. Nano-modelling
Theoretical and numerical techniques for predicting and understanding the behaviour of systems and processes with dimensions less than 100 nm.
4. Properties of nanomaterials
Size-dependent properties of materials that are structured on dimensions of 100 nm or below.
Devices, systems and machines
5. Bionanotechnology
The use of nanotechnology to study biological processes at the nanoscale, and the incorporation of nanoscale systems and devices of biological origin in synthetic structures.
6. Nanomedicine
The use of nanotechnology for diagnosing and treating injuries and disease.
7. Functional nanotechnology devices and machines
Nanoscale materials, systems and devices designed to carry out optical, electronic, mechanical and magnetic functions.
8. Extreme and molecular nanotechnology
Functional devices, systems and machines that operate at, and are addressable at, the level of a single molecule, a single atom, or a single electron.
Nanotechnology, the economy, and society
9. Nanomanufacturing
Issues associated with the commercial-scale production of nanomaterials, nanodevices and nanosystems.
10. Nanodesign
The interaction between individuals and society with nanotechnology. The design of products based on nanotechnology that meet human needs.
11. Nanotoxicology and the environment
Distinctive toxicological properties of nanoscaled materials; the behaviour of nanoscaled materials, structures and devices in the environment.

All comments gratefully received!

From the gallery

For no particular reason other than it is a really nice image, here’s a picture from the Sheffield Polymer Physics Group. It’s an AFM image of a thin film of a block copolymer – a molecule with a long section that can crystallise (poly ethylene oxide), attached to a shorter length of a non-crystallisable material (poly vinyl pyridine). What you can see is a crystal growing from a screw dislocation. The steps have a thickness of a single molecule folded up a few times.

AFM image of a block copolymer growing from a screw dislocation

Image width 20 microns. Image by Dr Cvetelin Vaslilev, image post-treatment by Andy Eccleston.

Scenarios for the future of transport

The UK government established a new horizon-scanning unit in its Office and Science and Technology a few years ago, and this has now issued its first report. This takes a look at likely scenarios for transport infrastructures over the next fifty years, but since transport and communications are so central to our economy these scenarios form a fairly comprehensive look at how new technology might change the way we live. In particular, they cover three big questions about technology and the future:

  • Where will the energy that currently underwrites our lifestyle in the developed world come from?
  • How will we exploit the growing amount of information processing and communication power we will have at our disposal?
  • Will the world carry on its trend to centralisation in manufacturing and energy generation, or will we see a switch to increasingly decentralised modes of production?

    • The web-site has links to lot of excellent material, including many interesting, specially commissioned background papers, but perhaps the most interesting things are the Project overview (54 page PDF), and the Scenarios (89 page PDF). The latter bring the subject to life with four plausible, but highly contrasting, scenarios for how things might turn out.

    The techno-optimist’s scenario is called “Perpetual motion”. Here it’s assumed that technology has managed to overcome the problems of sustainable energy with some combination of the hydrogen economy, nuclear fuels, coal and carbon sequestration. Everything and everyone is plugged in to the information grid, and the major problem the world faces is workplace stress. There’s a green nirvana too: “Urban colonies” imagines a future of sustainable urbanisation, where personal transport is discouraged by heavy taxation. Energy comes from microgrids, there is universal recycling and reuse. People are prosperous, but the economy revolves around fewer goods and more services. Iin short, it’s a vision of the future in which everywhere looks like Copenhagen, rather than Seoul. But, on the principle that the statistically most accurate way of predicting the weather tomorrow is to look out of the window today, what is considered the most likely scenario is called “Good intentions”. This is a world in which hard decisions have been put off until too late. Transport is both highly congested and highly priced; there’s been some progress with biofuels but accelerating climate change is leading to increasingly frequent weather disasters. Both prosperity and personal freedom are compromised.

    Techno-optimists think that the accelerating pace of technological advances will determine how the world changes, while green-tinged social liberals believe that the future can be deliberately shaped by human, democratic values. There is a third, much uglier, possibility; that we will be unable to prevail over overwhelming societal strains imposed by external shocks. This is the world of the most pessimistic scenario, “Tribal trading”. Here an early end to the era of cheap energy has stripped the veneer from our globalised world. A decline in oil production has led to spiralling oil prices. Economic depression has ended with the near-complete collapse of world and national financial systems, with resource wars and environmental disasters adding to the gloom. It’s a world of walls and borders and vegetable gardens, in which the 90’s experience of Cuba offers some of the best coping strategies. Some technology survives, and with travel over even modest distances prohibitively difficult and expensive, robust communications are more important than ever. For advice, we’re directed to the poet Gary Snyder:

    “What is to be done? Learn to be more self-reliant, reduce your desires, and take care of yourself and your family”.

    Throbbing gels

    This month’s edition of Nano Letters includes a paper from our Sheffield soft nanotechnology group (Jon Howse did most of the work, assisted by chemists Colin Crook and Paul Topham and beam line scientists Anthony Gleeson and Wim Bras, with me and Tony Ryan providing inspiration and/or interference) demonstrating the direct conversion of chemical energy to mechanical energy at the single molecule level. This is a development of the line of work I described here. Our idea is to combine a macromolecule which changes size in response to a change in the acidity of its surroundings with a chemical reaction which spontaneously leads to an oscillation in the acidity, to get a cyclic change in size of the polymer molecule. The work is summarised in a piece on nanotechweb.org.

    Nanotechnologies, public engagement and the policy makers

    I was in London on Monday, making a brief appearance before the Nanotechnology Issues Dialogue Group. This is the UK government committee that brings together officials from all Government departments with an interest in nanotechnology, to coordinate the government’s response to the issues raised by the Royal Society report. I was there to talk about the work of Nanotechnology Engagement Group, a body funded by the government’s Office of Science and Technology and run by the NGO Involve.

    The role of the NEG is essentially to carry out a rolling meta-study of public engagement exercises around nanotechnology in the UK and elsewhere; I’m chairing it and together with project director Richard Wilson we were giving the government officials a bit of a preview of our first report, which will be published in a month or so. I’ll wait until the report is out before saying much about it, but in the spirit of open government I’m sure the officials won’t mind me reproducing the pictorial record of the meeting below.

    and when did you last see your father?
    Richard Jones attempts to persuade the government officials of the Nanotechnology Issues Dialogue Group of the importance of public engagement.

    Let’s prevail

    Martyn Amos draws our attention to the collection of dangerous ideas on The Edge – the website of every popular science writer’s favourite literary agent, John Brockman. He asked a collection of writer-scientists to nominate their dangerous idea for 2006, and the result has something for everyone. Like Martyn, I very much like Lynn Margulis’s comments about the bacterial origins of our sensory perceptions. I’d want to go further, with the statement that human brains have more in common with colonies of social bacteria than with microprocessors.

    Devotees of the nanobot have Ray Kurzweil arguing that radical life extension and expansion, enabled by radical nanotechnology, is as inevitable as it is desirable. The apparent problems of overpopulation will be overcome because “molecular nanoassembly devices will be able to manufacture a wide range of products, just about everything we need, with inexpensive tabletop devices. “ Readers of Soft Machines will already know why I think Drexlerian nanotechnology isn’t going to lead us to this particular cornucopia. To my mind, though, the biggest danger of radical life extension isn’t overpopulation; it’s stagnation and boredom. Every generation has needed its angry young men and women, its punk rockers, to spark its creativity, and even as I grow older the thought of the world being run by a gerontocracy doesn’t cheer me up.

    So I’m with Joel Garreau, in hoping that despite environmental challenges and the frightening speed of technological change, we’ll see “the ragged human convoy of divergent perceptions, piqued honor, posturing, insecurity and humor once again wending its way to glory”. In the nice phrase Garreau used in his book Radical Evolution – let’s prevail.

    At the year’s turning

    All the best to Soft Machines readers for the New Year, and warm congratulations to my collaborator and friend Tony Ryan, Professor of Chemistry at Sheffield University, who was awarded an OBE for services to science in the Queen’s New Year’s Honours. For those readers unfamiliar with the intricacies of the British honours system, that means he’s been made an Officer of the Order of the British Empire. Yes, I know, Britain hasn’t got an empire any more, but the whole point of chivalry is to be archaic…

    The UK Government’s research programme into the potential risks of nanoparticles

    As trailed in my last post, the UK government has published the first report (Characterising the risks posed by engineered nanoparticles: a first UK Government research report – a 55 page PDF) from its programme of research into the potential health and environmental risks of engineered, free nanoparticles. Or rather, it’s published a document that reveals that there isn’t really a programme of research at all, in the sense of an earmarked block of funds and a set of research goals and priorities. Instead, the report describes an ad-hoc assortment of bits and pieces of research funded by all kinds of different routes. The Royal Society’s response is sceptical, stressing that the report “reveals that no money has been specifically set aside for important research into, for example, how nanoparticles ultra small pieces of material might penetrate the skin.”

    It’s clear, then, that if there is a nanotoxicity bandwagon developing (as identified by TNTlog), UK government is being pretty half-hearted about jumping on. I don’t think this is an entirely bad thing. Rather than joining some auction to declare what arbitrary percentage of their nanotechnology spend goes on toxicology, it makes sense to take a cold look at what research needs to be done (taking a realistic, hype-free view of how much of this stuff there really is in the work-place and the market), and what research is already going on. No-one gains by duplicating research, and identifying the gaps and the real needs is a good place to start.

    What the government should understand, though, is that when it does identify knowledge gaps, it has to be forward in filling them. Money has to be ear-marked, and if necessary capacity has to be built. One can’t rely on the scientific market, as it were, by expecting research proposals in the required areas to come forward spontaneously. Toxicology, occupational health and environmental science are crucially important , but they are often not exciting science as that would be defined by a Research Council peer review panel.

    David Tabor 1913-2005

    I was sorry to learn that David Tabor, Emeritus Professor of Physics at Cambridge University, died on Saturday at the age of 92. Tabor was a brilliant and insightful experimental physicist whose name is perhaps not very widely known outside the scientific community. This is a pity, because he has a substantial claim to be considered one of the founding fathers of nanoscience.

    Tabor began his research career in Australia, working for Council for Scientific and Industrial Research on lubricants and bearings. After moving to Cambridge University in 1946, he essentially created our modern understanding of the nanoscale origins of friction. His classic monograph on friction, written with F.P. Bowden in 1950, The Friction and Lubrication of Solids, is still in print and still very much worth reading. Tabor’s work on friction made him understand the importance of understanding the nature and structure of surfaces at the atomic level, and his group in the Cavendish Laboratory made major contributions to the development of surface science. Perhaps the highlight of his work on fundamental surface physics was his development of an apparatus to measure the van der Waals force between atomically smooth mica surfaces. This Surface Forces Apparatus, developed in the late ’60’s and early ’70’s in collaboration with his students Winterton and Israelachvili, was a technical tour de force, able to control and measure the separation between two surfaces with Angstrom resolution.

    Tabor retired in 1981, but he was frequently to be found in the Cavendish Laboratory throughout the next 20 years. I joined the Cavendish as a lecturer in his old group in 1989, and thus I was lucky enough to be able to spend a great deal of time talking to him in that period. He was a great man to discuss physics with; despite his eminence and many honours he was modest and unassuming, yet with a tremendous insight into the way matter behaves at the nanoscale. Indeed, the recent surge of experimental studies of friction made possible by new tools like the atomic force microscope has only served to remind people how accurate Tabor’s intuition was.

    Self-assembly vs self-organisation – can you tell the difference?

    Self-assembly and self-organisation are important concepts in both nanotechnology and biology, but the distinction between them isn’t readily apparent, and this can cause considerable confusion, particularly when the other self-word – self-replication– is thrown into the mix.

    People use different definitions, but it seems to me that it makes lots of sense to reserve the term self-assembly for equilibrium situations. As described in my book Soft Machines, the combination of programmed patterns of stickiness in nanoscale objects and constant Brownian motion mean that on the nanoscale complex 3-dimensional structures can assemble themselves from their component parts with no external intervention, purely driven by the tendency of systems to minimise their free energy in accordance with the second law of thermodynamics.

    We can then reserve self-organisation as a term for those types of pattern forming system which are driven by a constant input of energy. A simple prototype from physics are the well-defined convection cells you get if you heat a fluid from below, while in chemistry there are the beautiful patterns you get from systems that combine some rather special non-linear chemical kinetics with slow diffusion – the Belousov-Zhabotinsky reaction being the most famous example. A great place to read about such systems is the book by Philip Ball – The self-made tapestry – pattern formation in nature (though Ball doesn’t in fact make the distinction I’m trying to set up here).

    Self-assembly is pretty well understood, and it’s clear that at small length scales it is important in biology. Protein folding, for example, is a very sophisticated self-assembly process, and viable viruses can be made in the test-tube simply by mixing up the component proteins and nucleic acid. Self-organisation is much less well understood; it isn’t entirely clear that there are universal principles that underly the many different examples observed, and the relevance of the idea in biology is still under debate. There’s a very nice concrete example of the difference between the two ideas reported in a recent issue of Physical Review Letters (abstract here, full PDF preprint here). These authors consider a structural feature of living cells – the pattern of embedded proteins in the cell membrane – and ask, with the help of mathematical models, whether this pattern is likely to arise from equilibrium self-assembly or non-equilibrium self-organisation. The conclusion is that both processes can lead to patterns such as the ones observed, but that self-assembly leads to smaller scale patterns which take longer to develop.

    One thing one can say with certainty – living organisms can’t arise wholly from self-assembly, because we know that in the absence of a continuous supply of energy they die. In summary, viruses self-assemble, but elephants (perhaps) self-organise.