Anyone seen my plutonium?

The news that the UK nuclear reprocessing plant at Sellafield has ‘lost’ 29.6 kg of plutonium has been accompanied by much emphasis that this doesn’t mean that the stuff has physically gone missing. It’s simply an accounting shortfall, we are reassured, and a leader in the Times on the subject is notable for being probably the most scientifically literate editorial I’ve seen in a major newspaper for some time. Nonetheless, there is a real issue here, though it’s not related to fears of nuclear terrorism. The British Nuclear Group spokesperson is reported as saying “There is no suggestion that any material has left the site. When you have got a complicated chemical procedure, quite often material remains in the plant.” In other words, in all the complex and messy operations that are involved in nuclear reprocessing, some of the plutonium is not recovered, and remains in dilute solution in waste solvent. And in that form it’s potentially another small addition to the vast tanks of radioactive soup that form such a noxious legacy of the cold war nuclear programs in the UK, USA and the former Soviet Union.

Can nanotechnology help? The idea of a fleet of nanoscale submarines making their way through the sludge pools, picking out the radioactive isotopes and concentrating them into small volumes of high level waste which could then be safely managed, is an attractive one. Even more attractive is the idea that you could pay for the whole operation by recovering the highly valuable precious metals whose presence in nuclear waste is so tantalising. Is this notion ridiculously far-fetched? I’m not so sure that it is.

A very interesting technology that gives us a flavour of what is possible has been developed at Pacific Northwest National Laboratory. Nanoporous materials, with a very high specific surface area, are made using self-assembled surfactant nanostructures as templates. This huge internal surface area is then coated with a layer of molecules a single molecule thick; functional groups on the end of each of these molecules are designed to selectively bind a heavy metal ion. Such SAMMS – self-assembled monolayers on mesoporous supports – have been designed to selectively bind toxic heavy metals, like lead and mercury, precious metals like gold and platinum, and radioactive actinides like neptunium and plutonium, and they seem to work very effectively. Applications in areas like environmental clean-up and mining are obvious, in addition to applications to nuclear processing and clean-up.

Nanotech at Hewlett-Packard

There’s a nice piece in Slate by Paul Boutin reporting on his trip round the Hewlett-Packard labs in Palo Alto. The opening stresses the evolutionary, short term, character of the research going on there, stressing that these projects only get funded if they are going to make a fast return for the company, usually within five years. The first projects he mentions are about RFID (radio frequency identification), and these are discussed in terms of Walmart, supply chains and keeping track of your pallets. I can relate to this because my wife used to be a production planner. She used to wake up in the night worrying about whether there were enough plastic overcaps in the warehouse to pack the next week’s production, but she knew that the only way to find out for sure, despite all their smart SAP systems, was to walk down to the warehouse and look. But despite these mundane immediate applications it’s the technologies that are going to underlie RFID that also have such uncomfortable implications for a universal surveillance society.

The article moves on to talk about HP’s widely reported recent development of crossbar latches as a key component for molecular electronic logic circuits (see for example this BBC report, complete with a good commentary from Soft Machines’s frequent visitor, Philip Moriarty). The author rightly highlights the need to develop new, defect tolerant computer architectures if these developments in molecular electronics are to be converted into useful products. This nicely illustrates the point I made below, that in nanotechnology you may well need to develop systems architectures that accommodate the physical realities of the nanoscale, rather than designing the architecture first and hoping that you’ll be able to find low-level operations that will suit your preconceived notions .

Nanomagnetics

Nature has some very elegant and efficient solutions to the problems of making nanoscale structures, exploiting the self-assembling properties of information-containing molecules like proteins to great effect. A very promising approach to nanotechnology is to use what biology gives us to make useful nanoscale products and devices. I spent Monday visiting a nanotechnology company that is doing just that. Nanomagnetics is a Bristol based company (I should disclose an interest here, in that I’ve just been appointed to their Science Advisory Board) which exploits the remarkable self-assembled structure of the iron-storage protein ferritin to make nanoscale magnetic particles with uses in data storage, water purification and medicine.

Ferritin

The illustration shows the ferritin structure; 24 individual identical protein molecules come together to form a hollow spherical shell 12 nm in diameter. The purpose of the molecule is to store iron until it is needed; iron ions enter through the pores and are kept inside the shell – given the tendency of iron to form a highly insoluble oxide, if we didn’t have this mechanism for storing the stuff our insides would literally rust up. Nanomagnetics is able to use the hollow shell that ferritin provides as a nanoscale chemical reactor, producing nanoparticles of magnetic iron oxide or other metals of great uniformity in size, and with a protein coat that both stops them sticking together and makes them biocompatible.

One simple, but rather neat, application of these particles is in water purification, in a process called forward osmosis. If you filled a bag made of a nanoporous membrane with sugar syrup, and immersed the bag in dirty water, water would be pulled through the membrane by the osmotic pressure exerted by the concentrated sugar solution. Microbes and contaminating molecules wouldn’t be able to get through the membrane, if its pores are small enough, and you end up with clean sugar solution. There’s a small company from Oregon, USA, HTI , which has commercialised just such a product. Essentially, it produces something like a sports drink from dirty or brackish water, and as such it’s started to prove its value for the military and in disaster relief situations. But what happens if you want to produce not sugar solution, but clean water? If you replace the sugar by magnetic nanoparticles then you can sweep the particles away with a magnetic field and then use them again to produce another batch of water, producing clean water from simple equipment with only a small cost in energy.

The illustration of ferritin is taken from the Protein Database’s Molecule of the Month feature. The drawing is by David S. Goodsell, based on the structure determined by Lawson et al., Nature 349 pp. 541 (1991).

Renewable energy and incremental nanotechnology

Over the next fifty years, mankind is going to have to find large-scale primary energy sources that aren’t based on fossil fuels. Even if stocks of oil and gas don’t start to run out, the effects of man-made global warming are likely to become so pressing that the most die-hard climate-change sceptics will begin to change their tune. Meanwhile, the inhabitants of the rapidly developing countries of Asia will demand western-style standards of living, which in turn will demand western levels of energy use. Can nanotechnology help deliver the energy needed for all the world to have a decent standard of living on a sustainable basis?

Although wind and hydroelectric energy can make significant dents in total energy requirements, it seems that only two non-fossil primary energy sources really have the potential to replace fossil fuels completely. These are nuclear fission and photovoltaics (solar cells). Nuclear power has well known problems, though there have been recent signs of a change of heart by some environmentalists, notably James Lovelock, about this. Solar power is viable, in the sense that enough sunlight falls on the earth to meet all our needs, but the capital expense of current solar cell technology is too great for it to be economically viable, except in areas remote from the electricity grid.

To make a dent in the world’s total power needs we’re talking about bringing in many gigawatts (GW) of capacity per year (total electricity generating capacity in the UK was around 70 GW in 2002, in the USA it was 905 GW). Roughly speaking 65 million square meters (i.e. 65 square kilometers) of a moderately efficient photovoltaic gives you a GW of power. Here we see the problem of conventional silicon solar cells: a silicon wafer production plant with a 30 cm wafer process produces only 88,000 square meters a year; the cost is high and so is the energy intensity of the process, to the extent that it takes about 4 years to pay back the energy used in manufacture. We need to be able to make solar cells on a continuous basis, using a roll-to-roll process, more like a high volume printing press. A typical printing press takes just a few hours to process the same area of material as a silicon plant does in a year; at this rate we’re approaching the possibility of being able to make a GW’s worth of solar cells (roughly comparable to the output of a nuclear power station) from a year’s output from one production line. Several new technologies based on incremental nanotechnology promise to give us solar cells made by just this sort of cheap, large scale, low energy manufacturing process.

The most famous, and probably best developed technology is the Graetzel cell, invented by Michael Graetzel of the EPFL, Lausanne. This relies on nanostructured titanium dioxide whose surfaces are coated by a dye; the nanoparticles are then embedded in a polymer electrolyte to make a thin film which can be coated onto a plastic sheet. This process is being commercialised by a number of companies, including Konarka and Sustainable Technologies International. Other technologies use nanostructured forms of different kinds of semiconductors; companies involved include Nanosys, Nanosolar, and Solaris. A third class of non-conventional photovoltaics uses semiconducting polymers of the kind used in polymer light emitting diode displays, sometimes in conjunction with fullerenes. These technologies still need to make improvements to their efficiencies and lifetimes to be fully viable, but progress is rapid, and all offer the crucial benefit of low energy, large scale manufacturability.

It’s not at all clear which of these technologies will be the first to deliver the promised benefits. We shouldn’t forget that more conventional technologies, like thin film amorphous silicon, are also advancing fast – Unisolar has a commercial reel-to-reel process for producing this type of solar cell in quantity, with a projected annual production of 30 MW (i.e. 3% of a nuclear power station) coming soon. But it does seem as though this is one area where incremental nanotechnology could have a transformational and positive effect on the economy and the environment.

This discussion draws on two recent articles: Manufacturing and commercialization issues in organic electronics, by J.R. Sheats, Journal of Materials Research 19 1974 (2004), and Organic photovoltaics: technology and market”, by C.J. Brabec, Solar Energy Materials and Solar Cells, 83 273 (2004).

Nanotechnology in agriculture and food – the ETC group is against it

The environmental group ETC today released a report strongly opposed to what they refer to as “the atomic modification of food”. This is, of course, what we used to call “cooking”. ETC are now focusing their campaign against nanotechnology onto the agriculture and food industries, perhaps in the hope of replaying the controversy about genetic modification of food. What the report reveals, though, is the slow evolution of ETC’s muddled thinking on the subject.

There is some progress – ETC is now much more explicit about the possible benefits nanotechnology can bring. I very much welcome this statement, for example: “ETC acknowledges that nanotech could bring useful advances that might benefit the poor (the fields of sustainable energy, clean water and clean production appear promising…”. They also emphasise that the debate must go further than simply considering questions of safety. But still, when in doubt about what to criticise, it is the toxicological issues that they consistently return to. And here some of their biggest scientific misconceptions get trotted out again. “The nanoscale moves matter out of the realm of conventional chemistry and physics into “quantum mechanics” imparting unique characteristics to traditional materials – and unique health and safety risks”, the report states early on, and it later refers to “serious toxicity issues of quantum property changes”. But, ironically, it’s by thinking about food and the products of agriculture that we should see that this view that nanoparticles are especially toxic as a class due to quantum effects just can’t be tenable – many or even most food ingredients are naturally nanostructured or contain nanoparticles, but quantum mechanics plays no role in their properties and certainly doesn’t make them especially toxic. If you don’t want to ingest nanoparticles, you should stop drinking milk.

The results of this confusion are apparent in their discussion of nanotechnology in the agrochemical industry. Here there’s a lot of emphasis on the reformulation of agrochemicals in nanoscaled dispersions and in encapsulated and controlled release systems. I think this is an accurate reading of what the industry is concentrating on. But why are the properties of the reformulated products different? ETC admits to some uncertainty – “ETC is not in a position to evaluate whether or not pesticides formulated as nanosized droplets… exhibit property changes akin to the “quantum effects” exhibited by engineered nanoparticles.” But nonetheless, they add, “the impetus for formulating pesticides on the nanoscale is the changed behaviour of the reformulated product”. Here they are missing the point in a big way.

It’s not that any given different pesticide molecule behaves differently when it’s in a nanoscale emulsion than when it’s in a bulk solution; it’s simply that a higher proportion of the active molecules reach the destination where they do their job, and many fewer are wasted. Is this a good thing? If you are using this technology to weaponise a biological or chemical agent, it’s certainly frightening, and ETC are quite right to point out that this technology, like so many in the agrochemical industry, is a dual-use one. But from the point of view of environmental protection and the health of agricultural workers it is entirely a good thing – pesticides are toxic and potentially dangerous chemicals, and if the desired effect can be achieved with a smaller total pesticide burden that’s got to be a good thing. A scientist working formulating agrochemicals once told me “Currently we operate like a hospital that, rather than giving its patients medicines, sprays the hospital car park with antibiotics and hopes the visitors carry enough in on their feet to have some effect”. Finding ways to use powerful chemicals in more frugal and targeted ways seems a positive step forward to me. To elaborate on one example that ETC mention, Syngenta has been working on a long-lasting insecticide treatment for mosquito netting. This seems to me to be an appropriate, low cost and environmentally low impact contribution to a major problem of the developing world – malaria – and I would struggle to find anything about this sort of development one could sensibly oppose.

I’ve already discussed my views on ETC’s thesis that the replacement of commodities like cotton by nano-treated artificial fibres will greatly disadvantage the developing world below, and I’ll not add anything to that. I’ll simply point to the deep inconsistency of claiming on the one hand that nanotechnology poses a threat to farmers by taking markets away, and on the other hand being worried by the idea of new uses for crops as industrial feedstocks.

The section on nanotechnology in food manages to lose even more conviction. In the face of the difficulty of finding very much to get hold of, once again the theme of nanoparticle toxicity recurs. Food additives are being prepared in new, nanoscaled forms, and these haven’t been separately tested. They give as an example lycopene, a naturally occurring nutrient that BASF is bringing to market in a synthetic, nanodispersed form. They quote a patient explanation from BASF that once this stuff reaches the gut it behaves in just the same way as natural lycopene, lamely agree that “the explanation that all food is nano-scale by the time it reaches the bloodstream makes sense a-priori”, and then add the complete non-sequitur that we should worry that it hasn’t been tested in its nanoscale form. “What nano-scale substances are in the pipeline that have already been approved as food additives at larger scales but may now be formulated at the nano-scale with altered properties?” they ask. Let’s take this very slowly – food additives aren’t generally things that are developed on large scales – they’re molecules, and the usual state they arrive at the food manufacturer, and in which the consumer eats them, isn’t in large lumps, but in solution – i.e. about as nanodispersed as it is possible to get.

As in the first ETC report on nanotechnology, The Big Down, it isn’t that real things to worry about aren’t identified. The issues that surround “smart dust” and universal distributed intelligence are serious ones that need some real discussion, and it’s quite right for ETC to highlight this. There are very many very worrying aspects about the way the agri-food industry operates both in the developed and the developing worlds, and left unchecked I’m sure that developments in nanotechnology and nanomedicine could well end up being used in very negative ways. But as before, if ETC showed a bit more discrimination in what they criticised and a bit more understanding of the underlying science their contribution would be a lot more worthwhile.

I rather suspect that this report has been rushed out to hit the Thanksgiving slow news patch in the USA. Maybe it would have been better if ETC had sat on it a little longer, long enough to sort out their misunderstandings and get their message straight.

2005 – the year of nanotechnology (yet again)

When I was a small boy I could tell when Christmas was imminent; sometime around mid November the annuals published by my favourite comics appeared in the newsagents. There then followed six weeks of agonised waiting until the Beano annual appeared under the Christmas tree. Things are different now. My favourite comic characters now seem to have become leading politicians. I don’t have to wait until Christmas anymore, because I can just buy the annual myself, but sadly the annual I seem to be buying isn’t from the Beano but from the Economist.

The World in 2005 is written with the Economist’s usual mix of self-confidence and breezy optimism (I thought this prediction – “the Middle East will end the year looking either much better or far worse” – is an absolute classic of the genre). Nanotechnology gets a little box, predicting that 2005 will see the first year in which corporations outspend governments in nanotechnology, and that this will be the year in which we will see the arrival of many more nanotechnology-enabled products. The usual suspects are paraded – nano-strengthened tennis raquets, stain-resistant fabrics and self-cleaning window glass. Perhaps more interestingly, the article points to NEC’s announcement of a fuel-cell powered notebook PC, using carbon nanotubes in the electrodes. Other reports, however, suggest that this technology won’t be commercialised until 2007. Nonetheless, this does support the idea that energy technologies will be an important and potentially transformative application of near to medium-term nanotechnology.

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.

None but the brave deserve the (nano)fair

I’m in St Gallen, Switzerland, in the unfamiliar environment (for an academic) of a nanotechnology trade fair. The commercialisation arm of our polymer research activities in the University of Sheffield, the Polymer Centre, is one of the 14 UK companies and organisations that are exhibiting as part of the official UK government stall at Nanofair 2004.

It’s interesting to see who’s exhibiting. The majority of exhibitors are equipment manufacturers, which very much supports one conventional wisdom about nanotechology as a business, which is that the first people to make money from it will be the suppliers of the tools of the trade. Perhaps the second category are those countries and regions who are trying to promote themselves as desirable locations for businesses to relocate to. Companies that actually have nanotechnology products for actual consumer markets are very much in the minority, though there are certainly a few interesting ones there.

Alternative photovoltaics (dye-sensitised and/or polymer-based) are making a strong showing, helped by a lecture from Alan Heeger, largely about Konarka. This must be one of the major areas where incremental nanotechnology has the potential to make a disruptive change to the economy. A less predictable, but fascinating stand, for me, was from a Swiss plastics injection moulding company called Weidmann. Injection moulding is the familiar (and very cheap) way in which many plastic items, like the little plastic toys that come in cereal boxes, are made. Weidmann are demonstrating an injection moulded part in an ordinary commodity polymer with a controlled surface topography at the level of 5-10 nanometers. To me it is stunning that such a cheap and common processing technology can be adapted (certainly with some very clever engineering) to produce nanostructured parts in this way. Early applications will be to parts with optical effects like holograms directly printed in, and more immediately microfluidic reactors for diagnostics and testing.

The UK has a big presence here, and our stand has some very interesting exhibitors on it. I’ll single out Nanomagnetics which uses a naturally occurring protein to template the manufacture of magnetic nanoparticles with very precisely controlled sizes. These nanoparticles are then used either for high density data storage applications or for water purification, as removable forward osmosis agents. This is a great application of exploiting biological nanotechnology that very much is in accord with the philosophy outlined in my book Soft Machines; I should declare an interest in that I’ve just joined the scientific advisory board of this company.

The UK government is certainly working hard to promote the interests of its nascent nanotechnology industry. Our stall is full of well-dressed and suave diplomats and civil servants. However, one of the small business exhibitors was muttering a little that if only they were willing to spend the money directly supporting the companies with no-strings contracts, as the US government is doing with companies like Nanosys, then maybe the UK’s prospects would be even brighter.