I thought I’d post this spoof presentation for the fun of it on the responsible development of “unobtainium”, which seems to have some remarkable similarities with some other emerging technologies:

Last week, the Victoria branch of the Australian Education Union (AEU) passed a resolution recommending that “workplaces use only nanoparticle-free sunscreen” and that sunscreens used by members on children are selected from those “highlighted in the Safe Sunshine Guide produced by Friends of the Earth” as being nano-free.  The AEU also resolved to provide the Friends of the Earth Safe Sunscreen Guide and Recommendations to all workplaces their members are associated with.  Given what is currently known about sunscreens – nano and otherwise, I can’t help wonder whether this is an ill-advised move.

The debate over the safety or otherwise of nanoparticle-containing sunscreens has been going on for over a decade now.  Prompted by early concerns over possible penetration through the skin and into the body of the nanosized titanium dioxide and/or zinc oxide particles used in these products – and potential adverse impacts that might result – there has been a wealth of research into whether these small particles can actually get through the skin when applied in a sunscreen.  And the overall conclusion is that they cannot.  There have been a small number of studies that demonstrate that, under specific conditions, some types of nanoparticle might penetrate through the upper layers of the skin.  But the overwhelming majority of studies have failed to find either plausible evidence for significant penetration, or plausible evidence for adverse health impacts – a body of evidence that led the Environmental Working Group to make an about-face from questioning the use of nanoparticle-containing sunscreens to endorsing them in 2010.

So why is the AEU now advising against their use?  And why are they advocating selecting sunscreens based on a document that does not provide evidence-based advice on efficacy or safety – and may end up leading to decisions that increase the risk of sun-related skin damage in children (more on this below)? (Update 5/25/11 – see notes below)

In part, the answer lies in the uncertainty inherent in proving anything safe.  It’s not too difficult to show that something is unlikely to be harmful, or is probably safe.  But proving something is absolutely safe under all conditions of use is simply not possible – there is always some room for doubt.  This is why decisions on health risks are typically based on plausible risk and weight of evidence – evaluating the most reasonable and defensible interpretation of the data, and not basing decisions on speculation and fantasy.

With the use of nanoparticles in sunscreens, the weight of evidence is that they are safe and effective – and may be safer and more effective than a number of non-nanoparticle alternatives as they work by coating the skin rather than being absorbed into it.  That said, it’s always prudent to check whether anything has been missed with a relatively new technology like this, and so research is ongoing just to make doubly sure that the nanoparticles currently being used stay on top of the skin, and that manufacturers are using the safest possible types of nanoparticles.

But there is another reason I suspect why the ASU have released this advice, and that is due to a study using human volunteers that was published last year.

In this study by Brian Gulson and colleagues, sunscreens were formulated with zinc oxide particles made from a stable isotope of zinc that doesn’t occur in great abundance naturally: Zn-68. Using Zn-68 as a tracer, they were able to tell whether zinc from the applied sunscreen entered the bodies of the volunteers, and ended up in their blood and urine.

The detected presence of Zn-68 in the urine and blood of volunteers was used by Friends of the Earth Australia to renew their recommendations against using nanoparticle-containing sunscreens until more is known about their safety in.  And given the ASU’s reliance on the Friends of the Earth document, it seems to have influenced their decision to recommend not using nanoparticle-containing sunscreens.

But what does the Gulson study actually conclude?  In a nutshell, the researchers showed that:

• Small amounts of zinc from sunscreens containing any form of zinc oxide particles tested found their way into the blood and urine of volunteers.
• The amounts of zinc entering the body over the five day study were miniscule – around one thousandth of the concentration of zinc already in the volunteers’ bloodstream, and around one thousandth of the amount of zinc recommended in a person’s daily diet.
• Women in the test generally showed higher uptakes of zinc than men.
• Zinc levels in blood associated with the sunscreen peaked some days after applications ended, suggesting the zinc or zinc oxide was stored somewhere in or on the body and slowly released.
• For men, zinc uptake from sunscreens was independent of particle size.  For women, zinc uptake was greater from the sunscreens containing smaller particles.

So did the particles go through the skin?  The study only showed that the zinc passed through the skin, and did not provide any evidence of particle penetration.  Two possible explanations for this are that the particles penetrated and entered the bloodstream, or that the applied particles dissolved, and that it was dissolved zinc that was penetrating into the body.

Out of the two possibilities, there is minimal evidence for particle penetration being a plausible mechanism. On the other hand, zinc oxide is sparingly soluble, and under the acid-conditions of the outer layers of the skin the particles would have readily released zinc ions.  The weight of evidence to date therefore strongly supports dissolution of the particles and subsequent dermal penetration of dissolved zinc.  This is supported by the similarity in uptake seen in men of zinc for two different sizes of zinc oxide particles.

In other words, this study provides neither compelling evidence that nanoparticles in sunscreens can pass through the skin, or that they can lead to worrying internal exposure to harmful materials.  It did indicate on the other hand that any sunscreen containing zinc oxide will lead to zinc entering the body via the skin – including sunscreens that rely on large zinc oxide particles.

And this is where it is worth returning to the Friends of the Earth recommendations.

The Friends of the Earth Safe Sunscreen Guide recommends:

Use a nano-free zinc-based SPF 30+ broad spectrum sunscreen in conjunction with protective clothing, a broad-brimmed hat, sunglasses and shade to stay sun safe.

It goes on to list sunscreens that are “nano and chemical free”, “may use nano” and “use nano” (based on information from manufacturers and assumptions from Friends of the Earth).

Passing over the fact that Friends of the Earth are advocating the use of sunscreens that demonstrate the same behavior – zinc penetration through the skin into the body – as the sunscreens they recommend people don’t use, it’s hard to understand how this document provides an authoritative and evidence-based guide for the use of sunscreens on school children – as suggested by AEU.

For a start, this is a document that is specifically concerned with nanoparticle-containing sunscreens, and is not aimed at providing advice on selecting sunscreens as a whole based on their safety and efficacy.  It is advocating a specific course of action, and is not a tool for taking informed action. And in this respect alone it is a questionable document to be distributing to school workers. But it gets worse.

The sunscreens listed in the document are listed solely with respect to their nanoparticle content.  There is no – let me repeat that no – information on how effective these sunscreens are at protecting against UVA and UVB, and what the specific safety issues associated with their use are (update 5/25/11 – see notes below).  What is more, the top tier products – those that appear to be most strongly endendorsed by Friends of the Earth – also claim to be “free of UV-absorbing chemicals”.  In other words, this is a document that appears to be endorsing the use of products that do not necessarily protect against ultraviolet light. (Update 5/25/11 – see notes below).

To be fair to Friends of the Earth – and this is not a critique of their document so much as a questioning of its use as authoritative guidance – they do recommend the use of sunscreens providing substantial UV protection that are (presumably) based on large zinc oxide particles.  But if school workers were to base their choice of what to slather onto kids on the list of products, rather than the one sentence top level recommendation, they could well be applying sunscreens that do not protect against skin damage.

And this is my greatest concern here – by advocating the use of the Friends of the Earth document, AEU could actually be endangering the health of children in the care of their members. (Update 5/25/11 – see notes below)

Of course, there are important issues to grapple with here – including how appropriate sunscreens should be selected for use on children, irrespective of the technology being used.  But surely these selections should be based on the best possible evidence that is focused on what is most appropriate for the children, and not on an action campaign by an advocacy group, no matter how well intentioned.

Update, 5/25/11:  As clarified by Georgia Miller of Friends of the Earth Australia in the comments below, the sunscreens listed in the top tier of the Friends of the Earth document are all – as far as I can tell – marketed as offering SPF 30 + protection.  This is something that I do not think is explicitly clear in the document, and the heading of “nano and chemical-free”, clarified with “products also free of UV-absorbing chemicals” raises an obvious question to the naive reader over whether these products do indeed offer significant protection.  I also continue to have serious reservations over the use of a document designed to steer people away from nanoparticle-containing sunscreens as authoritative advice on sunscreen protection for children, given it’s lack of independent testing and evaluation of all significant factors that might affect choice in a given situation.  Nevertheless, given the protection ratings of the recommended sunscreens, I have on reflection retracted the statements made in regard to the protection offered above.

Okay so it’s more of a list of nanotech-enabled products than a lifestyle tool, but at the Project on Emerging Nanotechnologies, we’ve just released an iPhone version of our surprisingly successful web-based nanotech Consumer Products Inventory.

With findNano, it’s a piece of cake to search or browse through the 1000+ manufacturer-identified nanotechnology-enabled products in the inventory, directly from an iPhone or iPod Touch.  And the really cool part – if you come across something that isn’t in the inventory that you think should be, you can simply take a photo and email it to us directly from the app.  And if it passes muster, we’ll add it to the list.

The best way to discover what findNano is all about is probably to download it and take it for a spin (it’s free).  But here’s a quick overview for the curious:

The idea behind findNano is simply to give users a sense of where consumer product manufacturers are claiming to use nanotechnology, and how they are using it.  The app relies entirely on manufacturer claims (although claims that are too outlandish are ignored – Nano Ghiacciato didn’t make the cut for instance!), which means that listed products are only allegedly nanotech based – they have not been independently tested.  It also means that there are probably many products out there that are nanotech-enabled that haven’t been included, simply because manufacturers have been backward in being forward about the technology they are using.

That said, findNano does provide some insight into how nanotechnology is appearing in products that people are buying and using – something the US Environmental Protection Agency recognized when they used the web-based version to estimate the the range of engineered nanomaterials being produced (Nanoscale Materials Stewardship Program Interim Report, January 2009. Downloadable from here.)

In a nutshell, findNano allows you to do three things from your iPhone (or iPod Touch) – browse nanotech-enabled products, search for particular products, or submit products for possible inclusion in the inventory.

Selecting “Browse Products” allows you to scan through all 1000+ products currently listed, or to browse products by category, country or company.

The “Search” function allows products with specific terms in their names to be found – either from the whole inventory, or within specific categories.

“Submit a Product” is perhaps the most innovative part of the app, and allows users to take a snap of new nanotech-enabled products they stumble across, and send it to the Product on Emerging Technologies for possible inclusion in the inventory.  Nanotech product crowd-sourcing, using a nanotech-enabled product! (Yes, the iPhone does what it does because several of its components are engineered at the nanoscale).

How useful users find findNano remains to be seen.  But even if it’s just searching for the most bizarre use of nanotechnology that’s hit the streets so far, the app’s certainly a lot of fun to play around with.

And my contender for the most bizarre use so far?  Quite possibly The Handler.  What’s yours?

________________________

For more information on the Consumer Products Inventory, check out the web-based version at www.nanotechproject.org/consumer

More information on the findNano iPhone app can be found at http://nanotechproject.org/iphone

Sunday morning breakfast – a croissant, a coffee, and a stress-free morning.

But wait a minute…

I wonder how healthy all that butter is?  When did I last have my cholesterol levels checked?  Were they high?  Will my crisp, moist butter croissant push me into a French pastry-coronary?

And how about the coffee?  Didn’t I hear that caffeine gives you cancer?  Maybe that was just the Daily Mail on another cancer scare spree.

But there’s no smoke without fire…

Bother – what am I going to do?  I can already feel the panic rising!

Hang it all, I’ll just head out to MacDonald’s for a Sausage Egg and Cheese McGriddle, with a couple of hash browns on the side.  After all, didn’t someone say it’s healthy to start the day with a good breakfast?

Okay so I’m not really sitting down to croissants and coffee (more’s the pity), and I’m not going to rush off for a MacDonald’s breakfast.  But it is a Sunday morning, and with my brain in weekend mode (i.e. slow, relaxed, prone to roaming, uninformed speculation…), I found myself ruminating over something a friend said in an email a few days ago…

It concerned apparent resistance to having H1N1 flu shots in some quarters – an issue that is still bubbling away in the news.

I’m not going to write about the H1N1 vaccine directly – that would be irresponsible given my limited knowledge and my Sunday morning torpor.  But the issue does raise an interesting question of what happens when we are forced to consciously make decisions we might usually take for granted.

Martye’s email came on the tail of the latest poll from the Associated Press and GfK on people’s intentions to be vaccinated against H1N1.  The poll suggested that people were more wary of the new vaccine than “normal” flu vaccines, even though each year’s batch of flu vaccines is tailor made for that year’s prevalent virus strains – something that Martye had witnessed himself anecdotally.

He wondered how this played into people’s trust of science, scientists and government, and the role of mis-information in the decisions people make.

Because this is a Sunday morning, and there are important Sunday morning things to do (like find those croissants), this is a question that will have to wait until another day.  But it did get me thinking about the degree to which too much information, or a particular focus on an issue, can create a quandary by shifting the decisions we make from the subconscious to the conscious level.

As a species, we’re pretty adept at letting the subconscious parts of our brains do the heavy lifting when it comes to making decisions.  Just imagine how tedious life would be if we needed to analyze the pros and cons of every move or decision we made – much like the coffee and croissant illustration above, we would become paralyzed by indecision.  But we’d also more than likely end up making decisions that were more based on what we were comfortable with, rather than what was good for us.

This raises a real dilemma though, and one I don’t have a good answer to.  A major thrust of what I do is advocating for and enabling informed, evidence-based decision-making.  It’s something I believe in strongly – that in a science and technology-driven society, people should be enabled to make the best possible decisions for themselves and their society based on good evidence and strong scientific principles.

Yet it seems that where the decisions people need to make are far from black and white, forcing them to think about things could end up leading to choices that are more harmful than helpful.

The H1N1 flu vaccine seems to be a case in point.  If it was rolled out as just another annual flu vaccine, many people would have accepted it without question – the decision-making would have been at the subconscious level.

But because the issues of its importance and possible downsides have been raised explicitly, people are being forced to make a conscious decision whether to have it or not.

And kicking up the decision-making process from the subconscious domain to the conscious level has led to confusion and indecision.

So what should we do?  Should complex decisions be left in the hands of “experts?”  Should information – evidence – be withheld from people who don’t have the ability to process and use it?  Should we just accept that others are more informed than we are – and trust them?

At this point, every bone in my body is screaming that transparency, access to information and personal decision-making autonomy are moral obligations in a mature society, and that a hierarchical technocracy is not the way to go. Yet, if this is the case, we need to face the fact that more information isn’t necessarily a good thing on its own.  We need to develop the social tools to use it wisely, empowering individuals to make decisions that benefit themselves and society without leading to undue paralysis and harm.

This is a tough task.  I’m sure there are mountains of scholarly works that address it.  But I’ve yet to see any clear routes forward emerge.

Yet if we are going to cope with new challenges in a world where information spreads like wildfire, it seems more important than ever to work out how to empower people to make responsible and informed decisions on risks and benefits, without becoming paralyzed, or forced into relying on comfortable but possibly unhelpful decision-making shortcuts.

It seems that too much choice could be bad for the health.  But I suspect that not enough choice – and a lack of help, guidance and other tools for making informed decisions – will be worse for the health in the long run.

But that is most definitely a Monday morning problem.

Now, back to that croissant and coffee…

]]> http://2020science.org/2009/10/11/is-too-much-choice-bad-for-the-health/feed/ 14 http://2020science.org/2009/10/01/nano-from-the-1970s-don-eigler-eat-your-heart-out/ http://2020science.org/2009/10/01/nano-from-the-1970s-don-eigler-eat-your-heart-out/#comments Thu, 01 Oct 2009 19:01:03 +0000 Andrew Maynard http://2020science.org/?p=2298

Twenty years ago, Don Eigler became the first person to manipulate and position individual atoms, making the breakthrough that many consider a pivotal moment in modern nanotechnology.  Unknown to Don and the rest of IBM team though (I assume), they were pipped to the “nano” post a full ten years earlier… by an Italian sparkling wine…

Yes, “Nano Ghiacciato” – a Prosecco sparkling wine from San Pellegrino – was launched on the Italian market in 1979, a full decade before Eigler’s atom-moving experiments – and it’s still available!

The first "nano" product? Kees Brekelmans holding a bottle of "Nano Ghiacciato"

Having received an extensively researched account of “Nano Ghiacciato” from Cornelis  (Kees) Brekelmans this week, I couldn’t resist posting his account of the earliest “nano” product he’s come across – especially given the dual anniversary with Don Eigler’s work.

As Brekelmans notes,

San Pellegrino “Nano” is a white, sparkling wine, “Prosecco,” to be drunk “Ghiaciatto,” i.e. ice cold

It was launched in Italy in 1979, with an advertising campaign featuring the singer Amanda Lear. (scroll to the end of this post to see her in all her “nano” glory!)

In the presentation Kees emailed to me (“Nano – what’s in the name?”), he writes:

As Amanda explains, « nano è l’aperitivo ghiacciato per te » and « nano è il mio aperitivo con te »

“Nano is the iced drink for you” and “nano is the drink I’ll have with you” (a rather loose translation I’m afraid!)

And as she further elaborates,

« Il tuo nuovo aperitivo … grande come te,fresco con tefrizzante naturale, come te »

or “your new appetizer … big as you, naturally sparkling fresh with you, like you” (okay, so it’s a Google translation – my Italian’s a little rusty!).

To cap things off, Kees notes

“Nano Ghiacciato” does not figure in the Nanotechnology Consumer Products Inventory of the Woodrow Wilson Institute.  And neither does Amanda.

Guess we have some work to do – Italy and Amanda Lear, here we come!

Sadly, unlike Don’s work, “Nano Ghiacciato” isn’t nanotechnology – it’s just a small bottle of wine.

But it did spawn what is quite possibly the first “nano” song.  Amanda, play us out please…

(The video can also be viewed here)

Update 10/13/09:  At Cornelis’ request, I’ve revised his details in the post, and added the name of the presentation he sent through to me (“Nano – what’s in the name?”)

The Environmental Working Group (EWG) – a US-based non-profit organization committed to using public information to protect public health and the environment – has just released what is probably the most comprehensive evaluation to date of the safety and effectiveness of using titanium dioxide and zinc oxide nanoparticles in sunscreens.  And their conclusion?

On balance, EWG researchers found that zinc and titanium-based formulations are among the safest, most effective sunscreens on the market based on available evidence.

In other words, not only are zinc oxide and titanium oxide nanoparticle-based sunscreens OK, but they are safer and more effective than many non nanotechnology-enabled sunscreens.

What makes this statement so startling is that EWG is not known for treating regulators and industry with kid gloves.  This is how the organization describes it’s way of working:

Our research brings to light unsettling facts that you have a right to know. It shames and shakes up polluters and their lobbyists. It rattles politicians and shapes policy. It persuades bureaucracies to rethink science and strengthen regulation.

EWG is about as far as you can get from a bunch of industry lackeys.  Yet here they are endorsing one of the more controversial products of nanotechnology…

For the past few years, the safety of using nanometer-scale particles in sunscreens has been hotly debated.  As manufacturers have  turned increasingly to nanoscale mineral UV-blocking agents in place of more conventional chemicals, speculative questions over whether the nanometer-scale particles of titanium dioxide or zinc oxide being used could penetrate through the skin and harm people have been asked.  In the absence of conclusive safety-focused research, some groups have suggested that nanoparticle-based sunscreens should be avoided in favor of more conventional products, where there we have a clearer idea of the possible risks.  In 2007, Friends of the Earth published “A consumer guide for avoiding nano-sunscreens,” kicking off with:

Sun worshippers beware.  While slathering up with sunscreens to block dangerous ultra-violet (UV) rays you may be exposing yourself to a new danger.  Sunscreen manufacturers are adding nanoparticles to sunscreens to make sun-blocking ingredients like titanium dioxide and zinc oxide rub on clear instead of white. These nanoparticles are being added without appropriate labeling or reliable safety information.

Even EWG admit that their researchers were skeptical about the use of nanoparticles in sunscreens, and thought the organization would end up advising against their use.

Over the past few years, there has been a growing body of published data addressing the effectiveness and safety of nanoparticle-containing sunscreens.  EWG researchers ploughed through nearly 400 studies in their quest to assess what the upsides and downsides might be for consumers.  Importantly, they also compared these data to what is known about conventional UV-blocking agents like octinoxate and oxybenzone.

The result is a comprehensive, robust analysis that wouldn’t be out of place in a peer reviewed scientific journal.  The conclusions are highly relevant to consumers concerned over which sunscreens to use, companies paranoid over how they present their products, and governments wondering how to regulate nanotech-enabled sunscreens.  The report states:

Our study shows that consumers who use sunscreens without zinc and titanium are likely exposed to more UV radiation and greater numbers of hazardous ingredients than consumers relying on zinc and titanium products for sun protection. We found that consumers using sunscreens without zinc and titanium would be exposed to an average of 20% more UVA radiation — with increased risks for UVA-induced skin damage, premature aging, wrinkling, and UV-induced immune system damage — than consumers using zinc- and titanium-based products. Sunscreens without zinc or titanium contain an average of 4 times as many high hazard ingredients known or strongly suspected to cause cancer or birth defects, to disrupt human reproduction or damage the growing brain of a child. They also contain more toxins on average in every major category of health harm considered: cancer (10% more), birth defects and reproductive harm (40% more), neurotoxins (20% more), endocrine system disruptors (70% more), and chemicals that can damage the immune system (70% more) (EWG 2007).

We also reviewed 16 peer-reviewed studies on skin absorption, nearly all showing no absorption of small-scale zinc and titanium sunscreen ingredients through healthy skin. In a 2007 assessment the European Union found no evidence of nano-scale particles absorbing through pig skin, healthy human skin, or the skin of patients suffering from skin disorders (NanoDerm 2007). Overall, we found few available studies on the absorption of nano-scale ingredients through damaged skin, but nearly all other sunscreen chemicals approved for use in the U.S. also lack these studies.

In contrast to zinc and titanium, the common sunscreens octinoxate and oxybenzone absorb into healthy skin — in large amounts according to some studies. These 2 sunscreens can cause allergic reactions, can lead to hormone-driven uterine damage, and can act like estrogen in the body, raising potential concerns for breast cancer.

On balance, EWG researchers found that zinc and titanium-based formulations are among the safest, most effective sunscreens on the market based on available evidence. The easy way out of the nano debate would be to steer people clear of zinc and titanium sunscreens with a call for more data. In the process such a position would implicitly recommend sunscreen ingredients that don’t work, that break down soon after they are applied, that offer only marginal UVA protection, or that absorb through the skin.

EWG acknowledge that more research is still needed, alongside effective oversight, to ensure that nanotech-enabled sunscreens are as safe as possible.  But the key message is that the current balance of evidence supports their use as a safe and effective alternative to more conventional sunscreens.

I cannot emphasize enough how important this report is.  The analysis is credible and the conclusions drawn are supported by the current state of the science.  It should reduce consumer concerns over using nanoparticle-based sunscreens, and allow them to make informed decisions that will result in better UV protection.  It should also encourage companies developing and selling nanoparticle-enabled sunscreens to stop obscuring  the fact – either by avoiding any mention of nanoparticles, hiding behind silly euphamisms alike “micronized,” or coming up with elaborate explanations of why their product doesn’t actually contain any nanoparticles.  These are good products using an effective technology, and companies shouldn’t be shy to let people know!

That said, there is still work to be done.  There are gaps in our understanding of how titanium dioxide and zinc oxide nanoparticles behave on the skin and in the environment that it would be good to fill.  Approaches to testing these materials need to be fully evaluated. And regulators need to clarify the rules concerning the safe use of these materials.

Given what still isn’t known, EWG cautioned against the use of nanoparticles in cosmetics at the moment, where they are not being used to protect the wearer’s health.  But when it comes to protecting the skin the organization was clear – nanoparticle-based sunscreens.

End Notes

The full EWG report on “Nanotechnology & Sunscreens” can be read here.

This is part of a larger review of sunscreens, which is accessible here.

Something not covered in the EWG report is nanoparticle agglomeration.  Some companies have claimed that, while the basic size of titanium dioxide and zinc oxide particles they use is in the range of 1 – 100 nm, they form much larger agglomerates in the products and should therefore not be considered “nanoparticles.”  While this may be the case for some products, it isn’t universal, and there are still questions over whether large agglomerates could disaggregate when applied to the skin.  However, given the EWG’s findings and conclusions, the question of agglomeration doesn’t seem to be that important from a consumer’s perspective.

One concern over the use of titanium dioxide and zinc oxide nanoparticles in sunscreens is that these materials are photoactive, and could become more harmful when exposed to sunlight.  As the EWG report notes, most manufaturers treat the nanoparticles to supress their photoactivity.  Howere, there is some evidence that products containing photoactive particles could still be entering the market.   Whether this is important from a health perspective is unknown, although the indications are that it probably isn’t a significant concern when the particle-containing sunscreens are appolied to healthy skin.

]]> http://2020science.org/2009/07/03/nanotechnology-sunscreens/feed/ 17 http://2020science.org/2008/11/26/carbon-nanotubes-rock%e2%80%94literally/ http://2020science.org/2008/11/26/carbon-nanotubes-rock%e2%80%94literally/#comments Wed, 26 Nov 2008 23:03:42 +0000 Andrew Maynard http://2020science.wordpress.com/?p=496

A nanotechnology fix for high-end audio addicts?

I’m sitting at my computer watching a surreal balletic movie—a sheet of highly aligned carbon nanotubes is being slowly stretched, then allowed to slowly contract.  In the background is a soundtrack of traditional-sounding Chinese music.

At least I think the soundtrack is over-dubbed, until I realize that the music is coming directly from the nanotube sheet itself, which has been attached to a small amplifier.

And it suddenly dawns on me that I am watching something rather special—perhaps the biggest breakthrough in loudspeaker technology in decades…

The movie comes out of the lab of Kaili Jiang at Tsinghua University in Beijing, and accompanies a paper recently published on-line in the journal Nano Letters (Flexible, Stretchable, Transparent Carbon Nanotube Thin Film Loudspeakers, Xiao et al. DOI: 10.1021/nl802750z).

Jiang’s team has been perfecting a technique for growing “forests” of uniform carbon nanotubes on silicon wafers, and “drawing” them out into films just a few tens of nanometres thick.  These self-supporting films of closely aligned nanotubes have plenty of commercial potential, from transparent conducting surfaces to strong materials.  So it’s hard to imagine what prompted the research team hook one of their films up to an audio amplifier.

Yet at some point, some enterprising researcher took the initiative, and the music flowed…

Since the paper was posted on the Nano Letters website it has attracted a flood of web-chatter (for example, check out Michael Berger’s excellent coverage at Nanowerk, or the recent article in the Economist).  And much of it has focused on meshing the new technology with consumer electronics—phones, TV’s, laptop computers, even clothing that quite literally speaks volumes about the wearer (the nanotube films continue to work as an audio transducer when attached to fabric, and even when bent, stretched or otherwise manipulated).

But what caught my attention was the possibility here for high-end audio—not the aural mediocrity that consumers seem more than willing to put up with, but the drive to make sound production as real as… well, reality itself.

Surprisingly perhaps, nanotechnology hasn’t had much of a presence in the field of high-end audio so far—a sector that often adopts new technologies early on in the push to make ever-more exclusive, unique and audibly superior products.  The closest manufacturers have got to using nanotechnology (to my knowledge) are the rather superb 800D loudspeakers from Bowers and Wilkerson, that use micrometer-thin Chemical Vapour Deposition-formed diamond tweeters to produce some of the purest high notes possible (or so I’m told—the 800D’s are a tad above my pay grade!).

But the nanotube loudspeaker may change all that.  And here’s why:

Current loudspeaker technologies are the weak link in the audio chain—even the best loudspeakers distort the sound and add their own character to it to some degree.  And much of the problem lies in converting an electrical signal into a mechanical signal (an oscillating cone for instance), and thence into an acoustic signal.  Along the way, the purity of the sound is always compromised in some way.  And as a result, even a $20,000 pair of speakers will still have an audible influence on music heard through them.

The carbon nanotube film in contrast cuts out the mechanical stage, and makes it possible to convert an electrical signal directly into an audio signal.  Unlike any conventional loudspeaker I can think of, in a nanotube loudspeaker, there will be no moving parts.  This in itself would be a major leap forward in sound reproduction.  But there’s more.

In theory, the radiating surface of a nanotube loudspeaker could be made pretty large—meters square even—with every part of the surface generating sound in perfect coherence with every other part. This is a huge deal. It means having power and purity at the same time—something that is near-impossible with cheaper conventional loudspeakers, and barely possible with megabucks high-end models.

Add to this the electrical simplicity of the nanotube film (it presents a predominantly resistive load) and an ability to work over a very large frequency range, and you have a package this is looking very attractive, and might even have what it takes to make high quality digital speakers a practical reality—loudspeakers that take a digital signal from CD’s, DVD’s or computer audio files, and convert that signal directly into sound (without having to convert it into an analogue signal first—another weak link in the audio chain).

Even if these carbon nanotube films live up to just a fraction of their promise, this is a technology that should have any self-respecting audiophile addict in an ecstasy of anticipation.

Of course there are hurdles to overcome.  It’s unclear how quality control will affect sound quality, or how delicate the resulting transducers will be.  Some nifty electronics will also be needed to drive the nanotube loudspeakers to their maximum capability.

And then there is the question of safety.  It’s not clear whether the carbon nanotubes being used in Jiang’s lab match those that could cause health problems if inhaled, or whether there is any possibility of the films shedding potentially harmful carbon nanotubes.  But some judicious investigations on this front would seem in order—if only to assure people that listening to the finest quality high-end audio systems in the future will not end up being a terminally exhilarating experience.

There is also the cost of the carbon nanotubes themselves—which is still on the high end of expensive.

Actually, I’m not sure this is such a barrier, judging by what people will pay for the last word in high-end audio equipment.  Take the pinnacle of the Bowers and Wilkerson loudspeaker range for example—the Nautilus loudspeaker.  A result of five years’ development with the goal being perfection—or as close as is humanly possible—a pair will set you back in excess of $60,000.  Yet people still buy them!

In this business, people aren’t going to be phased by paying a few thousand dollars extra in the quest for audio nirvana.  Which is why I think that high-end loudspeaker manufacturers will be taking this new technology seriously—and most likely will be paving the way for more accessible carbon nanotube audio products that really do rock—figuratively as well as literally.

And as a last word, if you are one of the millions who couldn’t care a jot about high-end audio, check out Jiang’s nanotube-enabled musical flag below. What it lacks in quality, it certainly makes up for in novelty!

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Technical stuff (added Nov 27 2008)

For the technically minded, Jiang’s team aren’t entirely certain how the nanotube film works as a loudspeaker, but they are pretty sure it is due to the thermoacoustic effect, where the audio signal leads to rapid heating ad cooling of the nanotubes, leading to the formation of soundwaves (Michael Berger’s Nanowerk article includes useful background on the effect, and an animation of what is most likely going on in the nanotube speaker can be found in the Jiang paper supplemental material).  The result is that electrical signals are converted directly into soundwaves, simultaneously at each point on the film, and without any moving parts.  And it is this that makes the nanotube film so robust, versatile, and potentially high quality.

One downside of the thermoacoustic effect is that the frequency in a normal alternating current signal  is doubled when converted into sound, leading to a rather disconcerting shift in pitch in what is heard.  The nanotubes are heated just as much when the incoming signal goes negative as when it goes positive, leading to the doubling.  The trick Jiang and colleagues used to overcome this was to bias the electrical signal, so it was always positive (essentially making this a “class A” speaker).

Intriguingly, this tendency to double the incoming frequency shouldn’t be a problem if the nanotube film is used as a digital speaker.  The idea here is that a stream of digital pulses is fed directly into the loudspeaker, and the conversion of the signal from digital to analogue starts as the electrcal input is transformed into an acoustic output.  Because the pulses in a digital stream are all of the same polarity (the signal is either on or off, rather than varying from positive to negaitive), there will be no frequency doubling.  And the frequency response of the nanotube film is wide enough to convert the pulses of a digitally sampled audio track into sound waves that will be interpreted as music or speech by the human ear.

Just one niggling question – will feeding a digital signal directly into the nanotube film cause a melt-down through excessive heating?  It’s a possibility, but it would be a great experiment to try!

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UK Consumer Organization Which? Releases New Report

Who needs an emerging technologies blog when you have The Daily Mail?  For those of you that missed it, Wednesday’s on-line issue of the British tabloid newspaper highlighted

“The beauty creams with nanoparticles that could poison your body”

I’m so glad someone’s tracking this issue, while us folks over on the other side of the pond are dealing with the considerably less-interesting issues surrounding the incoming Obama administration.  The only trouble is, the Mail didn’t quite get it right.  In fact on a scale of 1 – 10, I’m not even sure they even make it to first base…

The article is based on a new report from the UK-based consumer organization Which? The report “Small Wonder? Nanotechnology and Cosmetics” [PDF, 3.9 MB] takes a clear-eyed view of nanotechnology-based cosmetics on the market, and asks what information is available about them, and whether or not users can be sure they are safe.

Unlike The Daily Mail story, this is an exceedingly good report.  If you are at all interested in nanotechnology and cosmetics, read it—it’s only a few pages long, but conveys the issues with clarity and style.  And by building on perspectives from industry, researchers and consumers, it presents a well-balanced overview.

The report is so accessible that it’s hardly worth summarizing it.  But here anyway are the take-home messages—Which?’s 10 point action plan:

• CO-ORDINATION:  The Government should establish a strategic stakeholder group to ensure there is effective input from all sectors of society and that the necessary measures are implemented and progress monitored.
• DEFINITIONS:  International agreement is needed on definitions for nanotechnologies.
• PRODUCTS:  The Government and EU need to understand what products are already on the market, in the pipeline or at the research stage and identifying those likely to raise most concerns based on current understanding.
• RESEARCH:  The Government and EU need to ensure that uncertainties around the environmental and health risks presented by some manufactured nano materials are urgently addressed – and ensure that research to enable this is funded.
• ASSESSMENT:  The Government and EU must provide clarity over how the safety of nano materials should be assessed given the current knowledge gaps.
• PRECAUTION:  The precautionary principle should be applied to products where there are potential risks, but where it is not currently possible to assess their safety, so that consumers are not put at risk.
• TRANSPARENCY:  Government and industry should be open about the uncertainties that some nano materials may raise, the research underpinning safety assessments as well as claims about potential benefits.
• REGULATION:  The EU needs to address the loopholes in regulations so that nano materials are included and there is clear guidance on how the regulations apply.
• INFORMATION:  The Government must ensure consumers, industry and regulators have clear information about where nano materials are being used and that any claims they make are true.
• ENGAGEMENT:  The public should be involved in meaningful discussions, at all levels, about the development of the technology, priority applications and any no-go areas.

This is a reasonable action plan, and a far cry from the scare-mongering pervading The Daily Mail story.

And unlike many of the reports that appeared in the popular press, Which? do an admirable job of fitting the story to the facts—rather than the other way around!

*At the time of posting, the report “Small Wonder? Nanotechnology and Cosmetics” wasn’t available on the Which? website.  As soon as it is up, the links in this posting will be updated.  In the meantime, the press release associated with the report can be accessed here.

Update, 11/7/08 – the report “Small Wonder? Nanotechnology and Cosmetics” can be accessed here [PDF, 3.9 MB]

[Minor edits made to the blog, 11/7/08]

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