Nanotechnology at the Royal Institution

For anyone in London and at a loose end next Monday, 1 November, there’s an event on at the Royal Institution from 7 pm to 8.30 pm: Nanotechnology: can something so tiny promise something so big?. It’s a debate about nanotechnology and its potential, chaired by the science writer Philip Ball, and featuring myself, Ray Oliver, an industrial nanotechnologist and one of the authors of the recent Royal Society report, and James Wilsdon, from the thinktank Demos, whose recent pamphlet about ways to engage the public about new technologies such as nanotechnology, See-through Science, I wrote about below. It should be an interesting evening.

Nanotechnology and the humble plastic bag

People wouldn’t usually think of the packaging industry as a place to look for technology driven advances – after all, how much high technology can there be in a crisp packet? But there’s one far-reaching area in which this industry sector is likely to be a major driver; that’s the incorporation of increasingly functional “smart tags” to facilitate supply chain management. The industry is moving from simple bar codes to RFID devices. As increasingly sophisticated computing power, communications and the capacity to sense the environment are added to RFID tags, we’ll be coming that much closer to the visions of ambient and ubiquitous computing and intelligent, networked artefacts that excite many people, and deeply worry many others.

For some background on the necessary enabling technologies, see this article – Polymers, nanotechnology and the future of packaging – that I wrote for the trade magazine Plastics in Packaging.

Let the scientists explain the science and the public speak for itself…

…is the rallying cry at the end of an opinion piece in today’s Times by Tracey Brown. The article decries both the defensiveness of scientists about nanotechnology and the tendency to treat non-governmental organisations like Greenpeace as proxies for public opinion. I think both of these are important points to make, though I don’t agree with the implicit conclusion that the public debate that is developing about nanotechnology is premature.

Who does Tracey Brown represent? Another NGO, of course – a pro-science pressure group called Sense about Science.

A new laboratory for semiconductor nanotechnology at Sheffield

A suite of refurbished laboratories in my department (Physics and Astronomy, University of Sheffield) was formally opened yesterday by Dame Julia Higgins, chair of EPSRC and Vice President of the Royal Society. The labs were refurbished with money from the Wolfson Foundation and the Royal Society and now house Maurice Skolnick’s work in semiconductor nanotechnology, as well as my own group’s labs. We marked the occasion with a set of scientific seminars.

It’s always interesting to get an update on what one’s colleagues are up to, and Maurice’s talk had some stunning examples of recent progress in semiconductor nanotechnology. I’ll show just one example.
Microresonator with quantum dots
The picture shows (left) a very small diameter photonic micropillar – one can make out a central enclosure, the cavity, sandwiched between two distributed Bragg reflectors (DBRs). These are multilayers of different semiconductors which behave as near-perfect mirrors for light; photons generated inside the cavity are essentially trapped by the mirrors and the edge of the pillar.

Simply to make these intricately structured micropillars is enough of an achievement (these were made at Sheffield by A Tahraoui and P W Fry). But within the cavity there is a further level of control. The pictures on the right show individual quantum dots, grown by self-assembly. These are incorporated within the cavity of the structure on the left (the transmission electron micrograph, labelled TEM, comes from Hopkinson and Cullis at Sheffield, the scanning tunelling micrograph, labelled STM, from Skolnick’s collaborator P.M. Koenraad at Eindhoven). The resulting structure simultaneously exploits the quantum effects that occur when electrons are confined within the quantum dots, with the optical confinement effects that occur when photons are trapped within the cavity. This allows simultaneous control both of the energies of electronic states in the quantum dot and of the way transitions between electronic states are coupled to the emission of light.

Quantum dots of this kind are already used to make solid state lasers for use in optical communications. What is really exciting Maurice and his colleagues, though, is the possibility that this kind of structure might be used as the basis for a quantum computer. Quantum computers, if one could get them to work, offer the possibility of massively parallel computing of a power unparalleled with our current CMOS technologies. The problem is that one has to keep quantum states isolated from the environment enough to work their quantum magic, but one still has to retain the ability to interact with the states enough to provide some kind of input and output to the computations. This kind of structure, with its very close control both of the states themselves, and, via the photonic control, of their interactions with the outside world, may just possibly do the trick.

Nanoparticles everywhere

Even the cleanest environments in the world are contaminated by nanoparticles; these are the product, not of the nascent nanotechnology industry, but of natural processes. In the southern ocean between Cape Horn and the Antarctic, on the West Coast of Ireland, swept by Atlantic gales, significant numbers of particles in the 10nm – 100 nm size range can be detected. An interesting recent article in Nature (subscription required) provides an interesting analysis of natural nanoparticles from a sampling site in Ireland. These nanoparticles include, as you would expect, some made out of sea-salt. As is also already well-known, another major contribution to natural nanoparticles comes from sulfates, whose origin is probably the reduction of a chemical called DMS which is generated by plankton. This process has raised lots of interest because of its potential importance as a mechanism of climate control feedback as demanded by the Gaia hypothesis. The recent Nature paper adds a third class of materials to the mix – miscellaneous organic chemicals, that according to the season can comprise more than 60% of the mass of sub-micron particles. These, too, probably have their origin in the plankton near the sea’s surface.

Sampling sites closer to urban life predictably show greater concentrations of organic nanoparticles, arising from volatile organic compounds emitted from vehicle exhausts and other manmade sources. Even here, one surprise is the potential importance of gaseous hydrocarbons of natural origin – isoprene and terpenes – as contributors to the total VOC load. There’s a good brief discussion of the nanoparticle exposure that arises as a result of pollution in the Royal Society Report.

None of this diminishes the need to do good toxicological studies on new nanoparticles if there’s any danger of human or environmental exposure to them. But it does emphasise that a great deal is known about the behaviour of nanoparticles in the enivronment. The trouble is that the knowledge arises in a field – atmospheric chemistry – that seems at first to be far removed from the interests of nanotechnology. Nomenclature differences may seem trivial, but they actually take on a bigger significance in today’s world of computer searches. None of the literature on this subject would show up if you did a search on terms like “nanoparticles in the environment”; for these people nanoparticles aren’t “nanoparticles”, they’re “Aitken-mode aerosols”.

My thanks to Brian Davison for taking me to The Moon for an in-depth briefing on all this.

Most people aren’t engineers

If you ask a materials scientist to choose a material, the first things they will think about are things like strength, fracture toughness and stiffness – the fundamental mechanical properties that characterise the material. A materials technologist will consider these properties too, but into the equation will also go how much the material costs and how easy it is to manufacture. But when a consumer is deciding whether to buy a product made from the material, it’s not numbers like the fracture toughness that swing the decision. It’s much more intangible qualities, the way the material looks and feels, and the way the design integrates the properties of the component materials with the form of the object, that determine whether the purchase is made, the price the product can command, and in many cases the pleasure that the consumer gets from owning and using the artefact. We can create new materials with controlled nanostructures, designing combinations of properties like strength and toughness to order. But who’s thinking about how to design those human-centred properties that are so important in giving value to materials? Only engineers care about fracture toughness, and most people aren’t engineers.

These reflections arise after a day spent in the London offices of the design house, the Conran Partnership. A small group of scientists, on the one hand, and designers, on the other, met to talk about industrial design, what’s good and bad about plastics, and whether there’s any way in which one could relate the emotional response of a consumer to a material to some scientific description. Some things are obvious – the heft that comes from high density, the apparent coldness of metal that comes from its high thermal conductivity. Some are less obvious, though – why is the anodised aluminium finish of my Apple Powerbook quite so desirable? It’s clearly something to do with roughness and texture, but what, exactly? And what about the time dependence of these qualities – what is it about leather, hardwoods and natural stone that make them age so gracefully?

The promise of nanotechnology – even the incremental kind that is a natural development of the last fifty years of materials science – is that it will allow us to design materials with properties to order. Because materials development is done by scientists and engineers, the properties that we tend to concentrate on are the physical ones like strength and stiffness. Now we need to understand the other factors that make an object desirable so we can design materials that fulfill those needs.

The future of nanotechnology; Drexler and Jones exchange letters

The current edition of “Physics World” carries a letter from K. Eric Drexler, written in response to my article in the August edition, “The future of nanotechnology“. There is also a response from me to Drexler’s letter. Since the letters section of Physics World is not published online, I reproduce the letters here. The text here is as the authors wrote them; they’ve been lightly edited to conform with Physics World house style in the printed version.

From Dr K.Eric Drexler to Physics World.

I applaud Physics World for drawing attention to the emerging field of artificial molecular machine systems. Their enormous productive potential is illustrated in biology and nature, where we observe molecular machine systems constructing molecular machinery, electronics, and digital information storage systems at rates measured in billions of tons per year. To understand the future potential of fabrication technologies (the foundation of all physical technology) we must examine the productive potential of artificial molecular machine systems. This field of enquiry has been a focus of my research since (Drexler 1981), which explored directions first suggested by (Feynman 1959).

I was surprised to find that Professor Richard Jones, in describing ���flaws in Drexler���s vision,��� ignores my physical analysis of productive molecular machine systems. He instead criticizes the implied hydrodynamics of an artist���s fantastic conception of a ���nanosubmarine��� ��� a conception not based on my work. It is, I think, important that scientific criticisms address the scientific literature, not artistic fantasies.

Professor Jones then offers a discussion of nanoscale surface forces, thermal motion, and friction that could easily leave readers with the impression that these present dire problems, which he implies have been ignored. But ignoring surface forces or thermal motion in molecular engineering would be like ignoring gravity or air in aeronautics, and physical analysis shows that well-designed molecular bearing interfaces can have friction coefficients far lower than those in conventional machines. These issues (and many others) are analyzed in depth, using the methods of applied physics, in Chapters 3, 5, and 10 of my book Nanosystems (Drexler 1992). Professor Jones fails to cite this work, noting instead only my earlier, popular book written for a general audience.

I agree with Professor Jones regarding the importance of molecular machine systems and the value of learning from and imitating biological systems at this stage of the development of our field. Where we part company is in our judgment of the future potential of the field, of the feasibility of molecular machine systems that are as far from the biological model as a jet aircraft is from a bird, or a telescope is from an eye. I invite your readers to examine the physical analysis that supports this understanding of non-biological productive molecular machine systems, and to disregard the myths that have sprung up around it. (One persistent myth bizarrely equates productive molecular machines with gooey nanomonsters, and then declares these to be impossible contraptions that grab and juggle atoms using fat, sticky fingers.)

There are many interesting research questions to address and technology thresholds to cross before we arrive at advanced artificial molecular machine systems. The sooner we focus on the real physics and engineering issues, building on the published literature, the sooner progress can be made. To focus on artist���s conceptions and myths does a disservice to the community.

K. Eric Drexler, PhD
Molecular Engineering Research Institute

K E Drexler 1981 Molecular Engineering: An approach to the development of general capabilities for molecular manipulation. Proc. Nat. Acad. Sci. (USA) 78:5275���5278
K E Drexler 1992 Nanosystems: Molecular Machinery, Manufacturing, and Computation (New York Wiley/Interscience)
R Feynman 1959 There���s Plenty of Room at the Bottom, in D Gilbert (ed) 1961 Miniaturization (New York Reinhold)

From Dr Richard A.L. Jones to Physics World.

I am pleased that Dr Drexler finds so much to agree with in my article. Our goals are the same; our research aims to understand how to make molecular scale machines and devices. Where we differ is how best to achieve that goal. The article was necessarily very brief in its discussion of surface forces, friction and thermal motion, and my book [1] contains a much fuller discussion, which does explicitly refer to Drexler���s book ���Nanosystems���. No-one who has read ���Nanosystems��� could imagine that Drexler is unaware of these problems, and it was not my intention in the article to imply that he was. Absurd images like the nanosubmarine illustration I used are widely circulated in popular writings about Drexlerian nanotechnology; they well illustrate the point that na?�ve extrapolations of macro-scale engineering to the nanoscale won���t work, but I���m happy to agree that Drexler���s own views are considerably more sophisticated than this. The point I was making was that the approach Drexler describes in detail in Nanosystems, (which he himself describes in the words: ���molecular manufacturing applies the principles of mechanical engineering to chemistry���), works within a paradigm established in macroscopic engineering and seeks to find ways to engineer around the special features of the nanoworld. In contrast to this, the design principles adopted by cell biology turn these special features to advantage and actively exploit them, using concepts such as self-assembly and molecular shape change that have no analogue in macroscopic engineering. Again, Dr Drexler and I are in agreement that in the short term biomimetic nanotechnology will be very fruitful and should be strongly pursued. We differ about the likely long term trajectory of the technology, but here, experiment will decide. Such is the unpredictable nature of the development of technology that I rather suspect that the outcome will surprise us both.

[1] Soft Machines, R.A.L. Jones, OUP (2004)

See-through Science

See-through Science is the title of a pamphlet by James Wilsdon and Rebecca Willis, from the left-of-centre UK think-tank, Demos. It’s a thoughtful reflection on how one ought to engage the public in the development of new technologies, with the emerging debate on nanotechnology taken as its focus. I particularly like the undogmatic tone. The report is very clear on the failings of the old ideas of the “deficit model” of public engagement, which unconvincingly and patronisingly maintained that it is sufficient to educate the public in the wise ways of science to convince them of its benefits. The report also warns against the danger that all debates about new technology get twisted round to focus narrowly on risk assessment. This is particularly timely in view of the way the nanotechnology debate has unfolded, with its excessive focus on the one issue of nanoparticle toxicity.

In terms of recommendations, perhaps for me the most telling point is the way the report highlights the almost complete absence of those parts of industry involved in nanotechnology from this debate. I think this situation needs to change, and very soon.

Then worms ‘ll come and eat thee oop

I had a late night in the prosperous, liberal, Yorkshire town of Ilkley last night, doing a talk and question and answer session on nanotechnology at the local Cafe Philosophique. An engaged and eclectic audience kept the discussion going well past the scheduled finish time. Two points particularly struck me. One recurring question was whether it was ever realistic to imagine that we can relinquish technological developments with negative consequences – “if it can be done, it will be done” was the comment made more than once. I really don’t like this conclusion, but I’m struggling to find convincing arguments against it. A more positive comment concerned the idea of regulation; we are used to thinking of this idea entirely in terms of narrow prohibitions – don’t release these nanoparticles into the environment, for example. But we need to work out how to make regulation a positive force that steers the technology in a desirable direction, rather than simply trying to sit on it.

(Non British readers may need to know that the headline is a line from a rather odd and morbid folk-song called “On Ilkley Moor baht hat”, sung mostly by drunken Yorkshiremen.)

Bad reasons to oppose nanotechnology: part 1

An article in this month’s The Ecologist Magazine, by the ETC group‘s Jim Thomas, makes an argument against nanotechnology that combines ignorance and gullibility with the risk of causing real harm to some of the worlds poorest people. What, he says, will happen to the poor cotton farmers and copper miners of the third world when nanotechnology-based fabric treatments, like those sold by the Nanotex Corp, make cotton obsolete, and carbon nanotubes replace copper as electrical conductors? This argument is so wrong on so many levels it’s difficult to know where to start.

To start with, is there any development economist who would actually argue that basing an third world economy on an extractive industry like copper mining is a good way to get sustained economic development and good living standards for the population as a whole? Likewise, it’s difficult to see that the industrial-scale farming of cotton, with its huge demand for water, can be anything other than an ecological disaster. Zambia is not exactly the richest country in Africa, and Kazakhstan is not a great advertisement for the environmental benefits of cotton growing.

And is the premise even remotely realistic? I wrote below about how novel the nanotex fibre treatments actually are; in fact there are many fibre treatments available now, some carrying a “nano” label, some not, which change handling and water resistance properties of a variety of textiles, both natural and artificial. These are just as likely to increase markets for natural fibres as for artificial ones. And as for nanotubes replacing copper, at a current cost of ��200 a gram this is not going to happen any time soon. What this argument demonstrates is that, unfortunately for a campaigning group, ETC is curiously gullible, with a propensity to mistake corporate press releases and the most uncritical nano-boosterism for reality.

This matters for two reasons. Firstly, on the positive side, nanotechnology really could benefit the environment and the world’s poor. Cheap ways of providing clean water and new sources of renewable energy are realistic possibilities, but they won’t happen automatically and there’ll be real debates about how to set priorities in a way which makes the technology bring benefits to the poor as well as the rich. What these debates are going to need from their participants is some degree of economic and scientific literacy. Secondly, there are some real potential downsides that might emerge from the development of nanotechnology; we need a debate that’s framed in a way that recognises the real risks and doesn’t waste energy and credibility on silly side-issues.

Luckily, there is at least one NGO that is demonstrating a much more sophisticated, subtle and intelligent approach – Greenpeace. The contribution of their chief scientist, Doug Parr, to a recent debate on nanotechnology held by the Royal Society in the light of their recent report, is infinitely more effective at focusing on the real issues.