Since COVID-19, we’ve been advised to wear face masks. It seems some of them may not be as safe as we assumed. First, the Health Canada advisory that was issued today, April 2, 2021 and then excerpts from an in-depth posting by Dr. Andrew Maynard (associate dean in the Arizona State University College of Global Futures) about the advisory and the use of graphene in masks.
Health Canada is advising Canadians not to use face masks that contain graphene because there is a potential that they could inhale graphene particles, which may pose health risks.
Graphene is a novel nanomaterial (materials made of tiny particles) reported to have antiviral and antibacterial properties. Health Canada conducted a preliminary scientific assessment after being made aware that masks containing graphene have been sold with COVID-19 claims and used by adults and children in schools and daycares. Health Canada believes they may also have been distributed for use in health care settings.
Health Canada’s preliminary assessment of available research identified that inhaled graphene particles had some potential to cause early lung toxicity in animals. However, the potential for people to inhale graphene particles from face masks and the related health risks are not yet known, and may vary based on mask design. The health risk to people of any age is not clear. Variables, such as the amount and duration of exposure, and the type and characteristics of the graphene material used, all affect the potential to inhale particles and the associated health risks. Health Canada has requested data from mask manufacturers to assess the potential health risks related to their masks that contain graphene.
Until the Department completes a thorough scientific assessment and has established the safety and effectiveness of graphene-containing face masks, it is taking the precautionary approach of removing them from the market while continuing to gather and assess information. Health Canada has directed all known distributors, importers and manufacturers to stop selling and to recall the affected products. Additionally, Health Canada has written to provinces and territories advising them to stop distribution and use of masks containing graphene. The Department will continue to take appropriate action to stop the import and sale of graphene face masks.
Face masks labelled as containing graphene or biomass graphene.
What you should do
Do not use face masks labelled to contain graphene or biomass graphene.
Consult your health care provider if you have used graphene face masks and have health concerns, such as new or unexplained shortness of breath, discomfort or difficulty breathing.
Dr. Andrew Maynard’s Edge of Innovation series features a March 26, 2021 posting about the use of graphene in masks (Note: Links have been removed),
Face masks should protect you, not place you in greater danger. However, last Friday Radio Canada revealed that residents of Quebec and Ottawa were being advised not to use specific types of graphene-containing masks as they could potentially be harmful.
The offending material in the masks is graphene — a form of carbon that consists of nanoscopically thin flakes of hexagonally-arranged carbon atoms. It’s a material that has a number of potentially beneficial properties, including the ability to kill bacteria and viruses when they’re exposed to it.
Yet despite its many potential uses, the scientific jury is still out when it comes to how safe the material is.
As with all materials, the potential health risks associated with graphene depend on whether it can get into the body, where it goes if it can, what it does when it gets there, and how much of it is needed to cause enough damage to be of concern.
Unfortunately, even though these are pretty basic questions, there aren’t many answers forthcoming when it comes to the substance’s use in face masks.
Early concerns around graphene were sparked by previous research on another form of carbon — carbon nanotubes. It turns out that some forms of these fiber-like materials can cause serious harm if inhaled. And following on from research here, a natural next-question to ask is whether carbon nanotubes’ close cousin graphene comes with similar concerns.
Because graphene lacks many of the physical and chemical aspects of carbon nanotubes that make them harmful (such as being long, thin, and hard for the body to get rid of), the indications are that the material is safer than its nanotube cousins. But safer doesn’t mean safe. And current research indicates that this is not a material that should be used where it could potentially be inhaled, without a good amount of safety testing first.
When it comes to inhaling graphene, the current state of the science indicates that if the material can get into the lower parts of the lungs (the respirable or alveolar region) it can lead to an inflammatory response at high enough concentrations.
There is some evidence that adverse responses are relatively short-lived, and that graphene particles can be broken down and disposed of by the lungs’ defenses.
This is good news as it means that there are less likely to be long-term health impacts from inhaling the material.
There’s also evidence that graphene, unlike some forms of thin, straight carbon nanotubes, does not migrate to the outside layers of the lungs where it could potentially do a lot more damage.
Again, this is encouraging as it suggests that graphene is unlikely to lead to serious long-term health impacts like mesothelioma.
However, research also shows that this is not a benign material. Despite being made of carbon — and it’s tempting to think of carbon as being safe, just because we’re familiar with it — there is some evidence that the jagged edges of some graphene particles can harm cells, leading to local damage as the body responds to any damage the material causes.
There are also concerns, although they are less well explored in the literature, that some forms of graphene may be carriers for nanometer-sized metal particles that can be quite destructive in the lungs. This is certainly the case with some carbon nanotubes, as the metallic catalyst particles used to manufacture them become embedded in the material, and contribute to its toxicity.
The long and short of this is that, while there are still plenty of gaps in our knowledge around how much graphene it’s safe to inhale, inhaling small graphene particles probably isn’t a great idea unless there’s been comprehensive testing to show otherwise.
And this brings us to graphene-containing face masks.
Here, it’s important to stress that we don’t yet know if graphene particles are being released and, if they are, whether they are being released in sufficient quantities to cause health effects. And there are indications that, if there are health risks, these may be relatively short-term — simply because graphene particles may be effectively degraded by the lungs’ defenses.
At the same time, it seems highly irresponsible to include a material with unknown inhalation risks in a product that is intimately associated with inhalation. Especially when there are a growing number of face masks available that claim to use graphene.
… There are millions of graphene face masks and respirators being sold and used around the world. And while the unfolding news focuses on Quebec and one particular type of face mask, this is casting uncertainty over the safety of any graphene-containing masks that are being sold.
And this uncertainty will persist until manufacturers and regulators provide data indicating that they have tested the products for the release and subsequent inhalation of fine graphene particles, and shown the risks to be negligible.
I strongly recommend reading, in its entirety , Dr. Maynard’s March 26, 2021 posting, Which he has updated twice since first posting the story.
In short. you may want to hold off before buying a mask with graphene until there’s more data about safety.
What a great image of bones! This December 3, 2020 University of Arkansas news release (also on EurekAlert) by Matt McGowan features research focused on bone material looks exciting. The date for the second study citation and link that I have listed (at the end of this posting) suggests the more recent study may have been initially overlooked in the deluge of COVID-19 research we are experiencing,
University of Arkansas researchers Marco Fielder and Arun Nair have conducted the first study of the combined nanoscale effects of water and mineral content on the deformation mechanisms and thermal properties of collagen, the essence of bone material.
The researchers also compared the results to the same properties of non-mineralized collagen reinforced with carbon nanotubes, which have shown promise as a reinforcing material for bio-composites. This research aids in the development of synthetic materials to mimic bone.
Using molecular dynamics — in this case a computer simulation of the physical movements of atoms and molecules — Nair and Fielder examined the mechanics and thermal properties of collagen-based bio-composites containing different weight percentages of minerals, water and carbon nanotubes when subjected to external loads.
They found that variations of water and mineral content had a strong impact on the mechanical behavior and properties of the bio-composites, the structure of which mimics nanoscale bone composition. With increased hydration, the bio-composites became more vulnerable to stress. Additionally, Nair and Fielder found that the presence of carbon nanotubes in non-mineralized collagen reduced the deformation of the gap regions.
The researchers also tested stiffness, which is the standard measurement of a material’s resistance to deformation. Both mineralized and non-mineralized collagen bio-composites demonstrated less stability with greater water content. Composites with 40% mineralization were twice as strong as those without minerals, regardless of the amount of water content. Stiffness of composites with carbon nanotubes was comparable to that of the mineralized collagen.
“As the degree of mineralization or carbon nanotube content of the collagenous bio-composites increased, the effect of water to change the magnitude of deformation decreased,” Fielder said.
The bio-composites made of collagen and carbon nanotubes were also found to have a higher specific heat than the studied mineralized collagen bio-composites, making them more likely to be resistant to thermal damage that could occur during implantation or functional use of the composite. Like most biological materials, bone is a hierarchical – with different structures at different length scales. At the microscale level, bone is made of collagen fibers, composed of smaller nanofibers called fibrils, which are a composite of collagen proteins, mineralized crystals called apatite and water. Collagen fibrils overlap each other in some areas and are separated by gaps in other areas.
“Though several studies have characterized the mechanics of fibrils, the effects of variation and distribution of water and mineral content in fibril gap and overlap regions are unexplored,” said Nair, who is an associate professor of mechanical engineering. “Exploring these regions builds an understanding of the structure of bone, which is important for uncovering its material properties. If we understand these properties, we can design and build better bio-inspired materials and bio-composites.”
Here are links and citations for both papers mentioned in the news release,
Nanomaterials researchers in Finland, the United States and China have created a color atlas for 466 unique varieties of single-walled carbon nanotubes.
The nanotube color atlas is detailed in a study in Advanced Materials about a new method to predict the specific colors of thin films made by combining any of the 466 varieties. The research was conducted by researchers from Aalto University in Finland, Rice University and Peking University in China.
“Carbon, which we see as black, can appear transparent or take on any color of the rainbow,” said Aalto physicist Esko Kauppinen, the corresponding author of the study. “The sheet appears black if light is completely absorbed by carbon nanotubes in the sheet. If less than about half of the light is absorbed in the nanotubes, the sheet looks transparent. When the atomic structure of the nanotubes causes only certain colors of light, or wavelengths, to be absorbed, the wavelengths that are not absorbed are reflected as visible colors.”
Carbon nanotubes are long, hollow carbon molecules, similar in shape to a garden hose but with sides just one atom thick and diameters about 50,000 times smaller than a human hair. The outer walls of nanotubes are made of rolled graphene. And the wrapping angle of the graphene can vary, much like the angle of a roll of holiday gift wrap paper. If the gift wrap is rolled carefully, at zero angle, the ends of the paper will align with each side of the gift wrap tube. If the paper is wound carelessly, at an angle, the paper will overhang on one end of the tube.
The atomic structure and electronic behavior of each carbon nanotube is dictated by its wrapping angle, or chirality, and its diameter. The two traits are represented in a “(n,m)” numbering system that catalogs 466 varieties of nanotubes, each with a characteristic combination of chirality and diameter. Each (n,m) type of nanotube has a characteristic color.
Kauppinen’s research group has studied carbon nanotubes and nanotube thin films for years, and it previously succeeded in mastering the fabrication of colored nanotube thin films that appeared green, brown and silver-grey.
In the new study, Kauppinen’s team examined the relationship between the spectrum of absorbed light and the visual color of various thicknesses of dry nanotube films and developed a quantitative model that can unambiguously identify the coloration mechanism for nanotube films and predict the specific colors of films that combine tubes with different inherent colors and (n,m) designations.
Rice engineer and physicist Junichiro Kono, whose lab solved the mystery of colorful armchair nanotubes in 2012, provided films made solely of (6,5) nanotubes that were used to calibrate and verify the Aalto model. Researchers from Aalto and Peking universities used the model to calculate the absorption of the Rice film and its visual color. Experiments showed that the measured color of the film corresponded quite closely to the color forecast by the model.
The Aalto model shows that the thickness of a nanotube film, as well as the color of nanotubes it contains, affects the film’s absorption of light. Aalto’s atlas of 466 colors of nanotube films comes from combining different tubes. The research showed that the thinnest and most colorful tubes affect visible light more than those with larger diameters and faded colors.
“Esko’s group did an excellent job in theoretically explaining the colors, quantitatively, which really differentiates this work from previous studies on nanotube fluorescence and coloration,” Kono said.
Since 2013, Kono’s lab has pioneered a method for making highly ordered 2D nanotube films. Kono said he had hoped to supply Kauppinen’s team with highly ordered 2D crystalline films of nanotubes of a single chirality.
“That was the original idea, but unfortunately, we did not have appropriate single-chirality aligned films at that time,” Kono said. “In the future, our collaboration plans to extend this work to study polarization-dependent colors in highly ordered 2D crystalline films.”
The experimental method the Aalto researchers used to grow nanotubes for their films was the same as in their previous studies: Nanotubes grow from carbon monoxide gas and iron catalysts in a reactor that is heated to more than 850 degrees Celsius. The growth of nanotubes with different colors and (n,m) designations is regulated with the help of carbon dioxide that is added to the reactor.
“Since the previous study, we have pondered how we might explain the emergence of the colors of the nanotubes,” said Nan Wei, an assistant research professor at Peking University who previously worked as a postdoctoral researcher at Aalto. “Of the allotropes of carbon, graphite and charcoal are black, and pure diamonds are colorless to the human eye. However, now we noticed that single-walled carbon nanotubes can take on any color: for example, red, blue, green or brown.”
Kauppinen said colored thin films of nanotubes are pliable and ductile and could be useful in colored electronics structures and in solar cells.
“The color of a screen could be modified with the help of a tactile sensor in mobile phones, other touch screens or on top of window glass, for example,” he said.
Kauppinen said the research can also provide a foundation for new kinds of environmentally friendly dyes.
Here’s a link to and a citation for the paper,
Colors of Single‐Wall Carbon Nanotubes by Nan Wei, Ying Tian, Yongping Liao, Natsumi Komatsu, Weilu Gao, Alina Lyuleeva‐Husemann, Qiang Zhang, Aqeel Hussain, Er‐Xiong Ding, Fengrui Yao, Janne Halme. Kaihui Liu, Junichiro Kono, Hua Jiang, Esko I. Kauppinen. Advanced Materials DOI: https://doi.org/10.1002/adma.202006395 First published: 14 December 2020
It’s not ready for the COVID-19 pandemic but if I understand it properly, wearing this clothing will be a little like wearing a thermometer and that could be very useful. A March 4, 2020 news item on Nanowerk announces the research (Note: A link has been removed),
Researchers have reported a new material, pliable enough to be woven into fabric but imbued with sensing capabilities that can serve as an early warning system for injury or illness.
The material, described in a paper published by ACS Applied Nano Materials (“Poly(octadecyl acrylate)-Grafted Multiwalled Carbon Nanotube Composites for Wearable Temperature Sensors”), involves the use of carbon nanotubes and is capable of sensing slight changes in body temperature while maintaining a pliable disordered structure – as opposed to a rigid crystalline structure – making it a good candidate for reusable or disposable wearable human body temperature sensors. Changes in body heat change the electrical resistance, alerting someone monitoring that change to the potential need for intervention.
I think this is an artistic rendering of the research,
“Your body can tell you something is wrong before it becomes obvious,” said Seamus Curran, a physics professor at the University of Houston and co-author on the paper. Possible applications range from detecting dehydration in an ultra-marathoner to the beginnings of a pressure sore in a nursing home patient.
The researchers said it is also cost-effective because the raw materials required are used in relatively low concentrations.
The discovery builds on work Curran and fellow researchers Kang-Shyang Liao and Alexander J. Wang began nearly a decade ago, when they developed a hydrophobic nanocoating for cloth, which they envisioned as a protective coating for clothing, carpeting and other fiber-based materials.
Wang is now a Ph.D. student at Technological University Dublin, currently working with Curran at UH, and is corresponding author for the paper. In addition to Curran and Liao, other researchers involved include Surendra Maharjan, Brian P. McElhenny, Ram Neupane, Zhuan Zhu, Shuo Chen, Oomman K. Varghese and Jiming Bao, all of UH; Kourtney D. Wright and Andrew R. Barron of Rice University, and Eoghan P. Dillon of Analysis Instruments in Santa Barbara.
The material, created using poly(octadecyl acrylate)-grafted multiwalled carbon nanotubes, is technically known as a nanocarbon-based disordered, conductive, polymeric nanocomposite, or DCPN, a class of materials increasingly used in materials science. But most DCPN materials are poor electroconductors, making them unsuitable for use in wearable technologies that require the material to detect slight changes in temperature.
The new material was produced using a technique called RAFT-polymerization, Wang said, a critical step that allows the attached polymer to be electronically and phononically coupled with the multiwalled carbon nanotube through covalent bonding. As such, subtle structural arrangements associated with the glass transition temperature of the system are electronically amplified to produce the exceptionally large electronic responses reported in the paper, without the negatives associated with solid-liquid phase transitions. The subtle structural changes associated with glass transition processes are ordinarily too small to produce large enough electronic responses.
If I understand this research rightly, they are creating a film made of carbon nanotubes that can stimulate the growth of nerve cells (neurons) thus creating a ‘living/nonliving’ hybrid or as they call it in the press release a ‘biosynthetic hybrid’.
An August 2, 2019 news item on Nanowerk introduces the research (Note 1: There seem to be some translation issues; Note 2: Links have been removed),
Carbon nanotubes able to take on the desired shapes thanks to a special chemical treatment, called crosslinking and, at the same time, able to function as substrata for the growth of nerve cells, finely tuning their growth and activity.
The research published in ACS Nano (“Chemically Cross-Linked Carbon Nanotube Films Engineered to Control Neuronal Signaling”), is a new and important step towards the construction of neuronal regenerative-interfaces to repair spinal injuries.
The study is the new achievement of a long-term and, in terms of results, successful collaboration between the scientists Laura Ballerini of SISSA (Scuola Internazionale Superiore di Studi Avanzati), Trieste, and Maurizio Prato of the University of Trieste. The work team has also been assisted by CIC biomaGUNE of San Sebastián, Spain.
The carbon nanotubes used in the research have been modified by appropriate chemical treatments: “For many years, in our laboratories we have been working on the chemical reactivity of carbon nanotubes, a fascinating but very difficult material to work. Thanks to our experience, we have crosslinked them or, to say it more clearly, we have treated the nanotubes so they could link themselves to one another thanks to specific chemical reactions. We have discovered that this procedure gives the material very interesting characteristics. For example, the material organises itself in a stable manner according to a precise shape, we choose: a tissue where nerve cells need to be planted, for example. Or around some electrodes” explains Professor Prato. “We know from previous research that nerve cells grow well on carbon nanotubes so they could be used as a surface to build hybrid devices to regenerate nerve tissues. It was necessary to ensure that this chemical modification did not compromise this process and study whether the interaction with neurons was altered”.
Towards biosynthetic hybrids
Professor Ballerini continues: “We have discovered that the chemical process has important effects because through this treatment we can modulate the activity of neurons, in terms of growth, adhesion and survival. These materials can also regulate the communication between neurons. We can say that the carpet of crosslinked carbon nanotubes interacts intensely and constructively with the nerve cells”. This interaction depends on how much the different carbon nanotubes are linked to each other, or rather crosslinked. The lower the link number among the nanotubes the higher the activity of neurons that grow on their surface. Through the chemical control of their properties, and of the links between them, it is possible to regulate the response of the neurons. Ballerini and Prato explain: “This is an intriguing result that emerges from the important and fruitful collaboration between our research groups involving advanced research in chemistry, nanoscience and neurobiology . This study provides a further step in the design of future biosynthetic hybrids to recover injured nerve tissues functions”.
There’s a very good November 11, 2019 article by Natalie Angier for the New York Times on carbon nanotubes (CNTs) and the colour black,
On a laboratory bench at the National Institute of Standards and Technology was a square tray with two black disks inside, each about the width of the top of a Dixie cup. Both disks were undeniably black, yet they didn’t look quite the same.
Solomon Woods, 49, a trim, dark-haired, soft-spoken physicist, was about to demonstrate how different they were, and how serenely voracious a black could be.
“The human eye is extraordinarily sensitive to light,” Dr. Woods said. Throw a few dozen photons its way, a few dozen quantum-sized packets of light, and the eye can readily track them.
Dr. Woods pulled a laser pointer from his pocket. “This pointer,” he said, “puts out 100 trillion photons per second.” He switched on the laser and began slowly sweeping its bright beam across the surface of the tray.
On hitting the white background, the light bounced back almost unimpeded, as rude as a glaring headlight in a rearview mirror.
The beam moved to the first black disk, a rondel of engineered carbon now more than a decade old. The light dimmed significantly, as a sizable tranche of the incident photons were absorbed by the black pigment, yet the glow remained surprisingly strong.
Finally Dr. Woods trained his pointer on the second black disk, and suddenly the laser’s brilliant beam, its brash photonic probe, simply — disappeared. Trillions of light particles were striking the black disk, and virtually none were winking back up again. It was like watching a circus performer swallow a sword, or a husband “share” your plate of French fries: Hey, where did it all go?
N.I.S.T. disk number two was an example of advanced ultra-black technology: elaborately engineered arrays of tiny carbon cylinders, or nanotubes, designed to capture and muzzle any light they encounter. Blacker is the new black, and researchers here and abroad are working to create ever more efficient light traps, which means fabricating materials that look ever darker, ever flatter, ever more ripped from the void.
The N.I.S.T. ultra-black absorbs at least 99.99 percent of the light that stumbles into its nanotube forest. But scientists at the Massachusetts Institute of Technology reported in September the creation of a carbon nanotube coating that they claim captures better than 99.995 of the incident light.
… The more fastidious and reliable the ultra-black, the more broadly useful it will prove to be — in solar power generators, radiometers, industrial baffles and telescopes primed to detect the faintest light fluxes as a distant planet traverses the face of its star.
Psychology and metaphors
It’s not all technical, Angier goes on to mention the psychological and metaphorical aspects,
Psychologists have gathered evidence that black is among the most metaphorically loaded of all colors, and that we absorb our often contradictory impressions about black at a young age.
Reporting earlier this year in the Quarterly Journal of Experimental Psychology, Robin Kramer and Joanne Prior of the University of Lincoln in the United Kingdom compared color associations in a group of 104 children, aged 5 to 10, with those of 100 university students.
The researchers showed subjects drawings in which a lineup of six otherwise identical images differed only in some aspect of color. The T-shirt of a boy taking a test, for example, was switched from black to blue to green to red to white to yellow. The same for a businessman’s necktie, a schoolgirl’s dress, a dog’s collar, a boxer’s gloves.
Participants were asked to link images with traits. Which boy was likeliest to cheat on the test? Which man was likely to be in charge at work? Which girl was the smartest in her class, which dog the scariest?
Again and again, among both children and young adults, black pulled ahead of nearly every color but red. Black was the color of cheating, and black was the color of cleverness. A black tie was the mark of a boss, a black collar the sign of a pit bull. Black was the color of strength and of winning. Black was the color of rage.
Then, there is the world of art,
For artists, black is basal and nonnegotiable, the source of shadow, line, volume, perspective and mood. “There is a black which is old and a black which is fresh,” Ad Reinhardt, the abstract expressionist artist, said. “Lustrous black and dull black, black in sunlight and black in shadow.”
So essential is black to any aesthetic act that, as David Scott Kastan and Stephen Farthing describe in their scholarly yet highly entertaining book, “On Color,” modern artists have long squabbled over who pioneered the ultimate visual distillation: the all-black painting.
Was it the Russian Constructivist Aleksandr Rodchenko, who in 1918 created a series of eight seemingly all-black canvases? No, insisted the American artist Barnett Newman: Those works were very dark brown, not black. He, Mr. Newman, deserved credit for his 1949 opus, “Abraham,” which in 1966 he described as “the first and still the only black painting in history.”
But what about Kazimir Malevich’s “Black Square” of 1915? True, it was a black square against a white background, but the black part was the point. Then again, the English polymath Robert Fludd had engraved a black square in a white border back in 1617.
Clearly, said Alfred H. Barr, Jr., the first director of the Museum of Modern Art, “Each generation must paint its own black square.”
Solomon and his NIST colleagues and the MIT scientists are all trying to create materials with structural colour, in this case, black. Angier goes on to discuss structural colour in nature mentioning bird feathers and spiders as examples of where you might find superblacks. For anyone unfamiliar with structural colour, the colour is not achieved with pigment or dye but with tiny structures, usually measured at the nanoscale, on a bird’s wing, a spider’s belly, a plant leaf, etc. Structural colour does not fade or change . Still, it’s possible to destroy the structures, i.e., the colour, but light and time will not have any effect since it’s the tiny structures and their optical properties which are producing the colour . (Even after all these years, my favourite structural colour story remains a Feb. 1, 2013 article, Color from Structure, by Cristina Luiggi for The Scientist magazine. For a shorter version, I excerpted parts of Luiggi’s story for my February 7, 2013 posting.)
The examples of structural colour in Angier’s article were new to me. However, there are many, many examples elsewhere,. You can find some here by using the terms ‘structural colour’ or ‘structural color’ in the blog’s search engine.
Angier’s is a really good article and I strongly recommend reading it if you have time but I’m a little surprised she doesn’t mention Vantablack and the artistic feud. More about that in a moment,
Massachusetts Institute of Technology and a ‘blacker black’
According to MIT (Massachusetts Institute of Technology), they have the blackest black. It too is courtesy of carbon nanotubes.
What you see in the above ‘The Redemption of Vanity’ was on show at the New York Stock Exchange (NYSE) from September 13 – November 29, 2019. It’s both an art piece and a demonstration of MIT’s blackest black.
With apologies to “Spinal Tap,” it appears that black can, indeed, get more black.
MIT engineers report today that they have cooked up a material that is 10 times blacker than anything that has previously been reported. The material is made from vertically aligned carbon nanotubes, or CNTs — microscopic filaments of carbon, like a fuzzy forest of tiny trees, that the team grew on a surface of chlorine-etched aluminum foil. The foil captures at least 99.995 percent* of any incoming light, making it the blackest material on record.
The researchers have published their findings today in the journal ACS-Applied Materials and Interfaces. They are also showcasing the cloak-like material as part of a new exhibit today at the New York Stock Exchange, titled “The Redemption of Vanity.”
The artwork, conceived by Diemut Strebe, an artist-in-residence at the MIT Center for Art, Science, and Technology, in collaboration with Brian Wardle, professor of aeronautics and astronautics at MIT, and his group, and MIT Center for Art, Science, and Technology artist-in-residence Diemut Strebe, features a 16.78-carat natural yellow diamond from LJ West Diamonds, estimated to be worth $2 million, which the team coated with the new, ultrablack CNT material. The effect is arresting: The gem, normally brilliantly faceted, appears as a flat, black void.
Wardle says the CNT material, aside from making an artistic statement, may also be of practical use, for instance in optical blinders that reduce unwanted glare, to help space telescopes spot orbiting exoplanets.
“There are optical and space science applications for very black materials, and of course, artists have been interested in black, going back well before the Renaissance,” Wardle says. “Our material is 10 times blacker than anything that’s ever been reported, but I think the blackest black is a constantly moving target. Someone will find a blacker material, and eventually we’ll understand all the underlying mechanisms, and will be able to properly engineer the ultimate black.”
Wardle’s co-author on the paper is former MIT postdoc Kehang Cui, now a professor at Shanghai Jiao Tong University.
Into the void
Wardle and Cui didn’t intend to engineer an ultrablack material. Instead, they were experimenting with ways to grow carbon nanotubes on electrically conducting materials such as aluminum, to boost their electrical and thermal properties.
But in attempting to grow CNTs on aluminum, Cui ran up against a barrier, literally: an ever-present layer of oxide that coats aluminum when it is exposed to air. This oxide layer acts as an insulator, blocking rather than conducting electricity and heat. As he cast about for ways to remove aluminum’s oxide layer, Cui found a solution in salt, or sodium chloride.
At the time, Wardle’s group was using salt and other pantry products, such as baking soda and detergent, to grow carbon nanotubes. In their tests with salt, Cui noticed that chloride ions were eating away at aluminum’s surface and dissolving its oxide layer.
“This etching process is common for many metals,” Cui says. “For instance, ships suffer from corrosion of chlorine-based ocean water. Now we’re using this process to our advantage.”
Cui found that if he soaked aluminum foil in saltwater, he could remove the oxide layer. He then transferred the foil to an oxygen-free environment to prevent reoxidation, and finally, placed the etched aluminum in an oven, where the group carried out techniques to grow carbon nanotubes via a process called chemical vapor deposition.
By removing the oxide layer, the researchers were able to grow carbon nanotubes on aluminum, at much lower temperatures than they otherwise would, by about 100 degrees Celsius. They also saw that the combination of CNTs on aluminum significantly enhanced the material’s thermal and electrical properties — a finding that they expected.
What surprised them was the material’s color.
“I remember noticing how black it was before growing carbon nanotubes on it, and then after growth, it looked even darker,” Cui recalls. “So I thought I should measure the optical reflectance of the sample.
“Our group does not usually focus on optical properties of materials, but this work was going on at the same time as our art-science collaborations with Diemut, so art influenced science in this case,” says Wardle.
Wardle and Cui, who have applied for a patent on the technology, are making the new CNT process freely available to any artist to use for a noncommercial art project.
“Built to take abuse”
Cui measured the amount of light reflected by the material, not just from directly overhead, but also from every other possible angle. The results showed that the material absorbed at least 99.995 percent of incoming light, from every angle. In other words, it reflected 10 times less light than all other superblack materials, including Vantablack. If the material contained bumps or ridges, or features of any kind, no matter what angle it was viewed from, these features would be invisible, obscured in a void of black.
The researchers aren’t entirely sure of the mechanism contributing to the material’s opacity, but they suspect that it may have something to do with the combination of etched aluminum, which is somewhat blackened, with the carbon nanotubes. Scientists believe that forests of carbon nanotubes can trap and convert most incoming light to heat, reflecting very little of it back out as light, thereby giving CNTs a particularly black shade.
“CNT forests of different varieties are known to be extremely black, but there is a lack of mechanistic understanding as to why this material is the blackest. That needs further study,” Wardle says.
The material is already gaining interest in the aerospace community. Astrophysicist and Nobel laureate John Mather, who was not involved in the research, is exploring the possibility of using Wardle’s material as the basis for a star shade — a massive black shade that would shield a space telescope from stray light.
“Optical instruments like cameras and telescopes have to get rid of unwanted glare, so you can see what you want to see,” Mather says. “Would you like to see an Earth orbiting another star? We need something very black. … And this black has to be tough to withstand a rocket launch. Old versions were fragile forests of fur, but these are more like pot scrubbers — built to take abuse.”
[Note] An earlier version of this story stated that the new material captures more than 99.96 percent of incoming light. That number has been updated to be more precise; the material absorbs at least 99.995 of incoming light.
Here’s an August 29, 2019 news release from MIT announcing the then upcoming show. Usually I’d expect to see a research paper associated with this work but this time it seems to an art exhibit only,
The MIT Center for Art, Science &Technology (CAST) and the New York Stock Exchange (NYSE) will present The Redemption of Vanity,created by artist Diemut Strebe in collaboration with MIT scientist Brian Wardle and his lab, on view at the New York Stock Exchange September 13, 2019 -November 25, 2019. For the work, a 16.78 carat natural yellow diamond valued at $2 million from L.J.West was coated using a new procedure of generating carbon nanotubes (CNTs), recently measured to be the blackest black ever created, which makes the diamond seem to disappear into an invisible void. The patented carbon nanotube technology (CNT) absorbs more than 99.96% of light and was developed by Professor Wardle and his necstlablab at MIT.
“Any object covered with this CNT material loses all its plasticity and appears entirely flat, abbreviated/reduced to a black silhouette. In outright contradiction to this we see that a diamond,while made of the very same element (carbon) performs the most intense reflection of light on earth.Because of the extremely high light absorbtive qualities of the CNTs, any object, in this case a large diamond coated with CNT’s, becomes a kind of black hole absent of shadows,“ explains Strebe.“The unification of extreme opposites in one object and the particular aesthetic features of the CNTs caught my imagination for this art project.”
“Strebe’s art-science collaboration caused us to look at the optical properties of our new CNT growth, and we discovered that these particular CNTs are blacker than all other reported materials by an order of magnitude across the visible spectrum”, says Wardle. The MIT team is offering the process for any artist to use. “We do not believe in exclusive ownership of any material or idea for any artwork and have opened our method to any artist,” say Strebe and Wardle.“
The project explores material and immaterial value attached to objects and concepts in reference to luxury, society and to art. We are presenting the literal devaluation of a diamond, which is highly symbolic and of high economic value.It presents a challenge to art market mechanisms on the one hand, while expressing at the same time questions of the value of art in a broader way. In this sense it manifests an inquiry into the significance of the value of objects of art and the art market,” says Strebe. “We are honored to present this work at The New York Stock Exchange, which I believe to be a most fitting location to consider the ideas embedded in The Redemption of Vanity.”
“The New York Stock Exchange, a center of financial and technological innovation for 227 years, is the perfect venue to display Diemut Strebe and Professor Brian Wardle’s collaboration. Their work brings together cutting-edge nanotube technology and a natural diamond, which is a symbol of both value and longevity,” said John Tuttle, NYSE Group Vice Chairman & Chief Commercial Officer.
“We welcome all scientists and artists to venture into the world of natural color diamonds. The Redemption of Vanity exemplifies the bond between art, science, and luxury. The 16-carat vivid yellow diamond in the exhibit spent millions of years in complete darkness, deep below the earth’s surface. It was only recently unearthed —a once-in-a-lifetime discovery of exquisite size and color. Now the diamond will relive its journey to darkness as it is covered in the blackest of materials. Once again, it will become a reminder that something rare and beautiful can exist even in darkness,”said Larry West.
The “disappearing” diamond in The Redemption of Vanity is a $2 Million Fancy Vivid Yellow SI1 (GIA), Radiant shape, from color diamond specialist, L.J. West Diamonds Inc. of New York.
The Redemption of Vanity, conceived by Diemut Strebe, has been realized with Brian L. Wardle, Professor of Aeronautics and Astronautics and Director of necstlab and Nano-Engineered Composite aerospace STructures (NECST) Consortium and his team Drs. Luiz Acauan and Estelle Cohen, in conjunction with Strebe’s residency at MIT supported by the Center for Art, Science & Technology (CAST).
ABOUT THE ARTISTS
Diemut Strebe is a conceptual artist based in Boston, MA and a MIT CAST Visiting Artist. She has collaborated with several MIT faculty, including Noam Chomsky and Robert Langer on Sugababe (2014), Litmus (2014) and Yeast Expression(2015); Seth Lloyd and Dirk Englund on Wigner’s Friends(2014); Alan Guth on Plötzlich! (2018); researchers in William Tisdale’s Lab on The Origin of the Works of Art(2018); Regina Barzilay and Elchanan Mossel on The Prayer (2019); and Ken Kamrin and John Brisson on The Gymnast (2019). Strebe is represented by the Ronald Feldman Gallery.
Brian L. Wardle is a Professor of Aeronautics and Astronautics at MIT and the director of the necstlab research group and MIT’s Nano-Engineered Composite aerospace STructures (NECST) Consortium. Wardle previously worked with CAST Visiting Artist Trevor Paglen on The Last Picturesproject (2012).
ABOUT THE MIT CENTER FOR ART, SCIENCE & TECHNOLOGY
A major cross-school initiative, the MIT Center for Art, Science & Technology (CAST) creates new opportunities for art, science and technology to thrive as interrelated, mutually informing modes of exploration, knowledge and discovery. CAST’s multidisciplinary platform presents performing and visual arts programs, supports research projects for artists working with science and engineering labs, and sponsors symposia, classes, workshops, design studios, lectures and publications. The Center is funded in part by a generous grant from the Andrew W. Mellon Foundation. Evan Ziporyn is the Faculty Director and Leila W. Kinney is the Executive Director.Since its inception in 2012, CAST has been the catalyst for more than 150 artist residencies and collaborative projects with MIT faculty and students, including numerous cross-disciplinary courses, workshops, concert series, multimedia projects, lectures and symposia. The visiting artists program is a cornerstone of CAST’s activities, which encourages cross-fertilization among disciplines and intensive interaction with MIT’s faculty and students. More info at https://arts.mit.edu/cast/ .
HISTORY OF VISITING ARTISTS AT MIT
Since the late 1960s, MIT has been a leader in integrating the arts and pioneering a model for collaboration among artists, scientists and engineers in a research setting. CAST’s Visiting Artists Program brings internationally acclaimed artists to engage with MIT’s creative community in ways that are mutually enlightening for the artists and for faculty, students and research staff at the Institute. Artists who have worked extensively at MIT include Mel Chin, Olafur Eliasson, Rick Lowe, Vik Muniz, Trevor Paglen, Tomás Saraceno, Maya Beiser, Agnieszka Kurant, and Anicka Yi.
ABOUT L.J. WEST DIAMONDS
L.J. West Diamonds is a three generation natural color diamond whole sale rfounded in the late 1970’s by Larry J. West and based in New York City. L.J. West has established itself as one of the world’s prominent houses for some of the most rare and important exotic natural fancy color diamonds to have ever been unearthed. This collection includes a vast color spectrum of rare pink, blue, yellow, green, orange and red diamonds. L.J. West is an expert in every phase of the jewelry process –from sourcing to the cutting, polishing and final design. Each exceptional jewel is carefully set to become a unique work of art.The Redemption of Vanity is on view at the New York Stock Exchange by appointment only.
Press viewing: September 13, 2019 at 3pmNew York Stock Exchange, 11 Wall Street, New York, NY 10005RSVP required. Please check-in at the blue tent at 2 Broad Street(at the corner of Wall and Broad Streets). All guests are required to show a government issued photo ID and go through airport-like security upon entering the NYSE.NYSE follows a business casual dress code -jeans & sneakers are not permitted.
No word yet if there will be other showings.
An artistic feud (of sorts)
Earlier this year, I updated a story on Vantablack. It was the blackest black, blocking 99.8% of light when I featured it in a March 14, 2016 posting. The UK company making the announcement, Surrey NanoSystems, then laid the groundwork for an artistic feud when it granted exclusive rights to their carbon nanotube-based coating, Vantablack, to Sir Anish Kapoor mentioned here in an April 16, 2016 posting.
This exclusivity outraged some artists notably, Stuart Semple. In his first act of defiance, he created the pinkest pink. Next, came a Kickstarter campaign to fund Semple’s blackest black, which would be available to all artists except Anish Kapoor. You can read all about the pinkest pink and blackest black as per Semple in my February 21, 2019 posting. You can also get a bit of an update in an Oct. 17, 2019 Stuart Semple proffile by Berenice Baker for Verdict,
… so I managed to hire a scientist, Jemima, to work in the studio with me. She got really close to a super black, and we made our own pigment to this recipe and it was awesome, but we couldn’t afford to put it into manufacture because it cost £25,000.”
Semple launched a Kickstarter campaign and was amazed to raise half a million pounds, making it the second most-supported art Kickstarter of all time.
The ‘race to the blackest’ is well underway, with MIT researchers recently announcing a carbon nanotube-based black whose light absorption they tested by coasting a diamond. But Semple is determined that his black should be affordable by all artists and work like a paint, not only perform in laboratory conditions. He’s currently working with Jemima and two chemists to upgrade the recipe for Black 3.2.
I don’t know how Semple arrived at his blackest black. I think it’s unlikely that he achieved the result by working with carbon nanotubes since my understanding is that CNTs aren’t that easy to produce.
Interesting, eh? In just a few years scientists have progressed from achieving a 99.8% black to 99.999%. It doesn’t seem like that big a difference to me but with Solomon Woods, at the beginning of this post, making the point that our eyes are very sensitive to light, an artistic feud, and a study uncovering deep emotions, getting the blackest black is a much more artistically fraught endeavour than I had imagined.
A June 3, 2019 news item on Nanowerk describes an inexpensive way to safely handle carbon nanotubes (CNTs), Note: A link has been removed,
With a little practice, it doesn’t take much more than 10 minutes, a couple of bags and a big bucket to keep nanomaterials in their place.
The Rice University lab of chemist Andrew Barron works with bulk carbon nanotubes on a variety of projects. Years ago, members of the lab became concerned that nanotubes could escape into the air, and developed a cheap and clean method to keep them contained as they were transferred from large containers into jars for experimental use.
More recently Barron himself became concerned that too few labs around the world were employing best practices to handle nanomaterials. He decided to share what his Rice team had learned.
“There was a series of studies that said if you’re going to handle nanotubes, you really need to use safety protocols,” Barron said. “Then I saw a study that said many labs didn’t use any form of hood or containment system. In the U.S., it was really bad, and in Asia it was even worse. But there are a significant number of labs scaling up to use these materials at the kilogram scale without taking the proper precautions.”
The lab’s inexpensive method is detailed in an open-access paper in the Springer Nature journal SN Applied Sciences (“The safe handling of bulk low-density nanomaterials”).
In bulk form, carbon nanotubes are fluffy and disperse easily if disturbed. The Rice lab typically stores the tubes in 5-gallon plastic buckets, and simply opening the lid is enough to send them flying because of their low density.
Varun Shenoy Gangoli, a research scientist in Barron’s lab, and Pavan Raja, a scientist with Rice’s Nanotechnology-Enabled Water Treatment center, developed for their own use a method that involves protecting the worker and sequestering loose tubes when removing smaller amounts of the material for use in experiments.
Full details are available in the paper, but the precautions include making sure workers are properly attired with long pants, long sleeves, lab coats, full goggles and face masks, along with two pairs of gloves duct-taped to the lab coat sleeves. The improvised glove bag involves a 25-gallon trash bin with a plastic bag taped to the rim. The unopened storage container is placed inside, and then the bin is covered with another transparent trash bag, with small holes cut in the top for access.
After transferring the nanotubes, acetone wipes are used to clean the gloves and more acetone is sprayed inside the barrel so settling nanotubes would stick to the surfaces. These can be recovered and returned to the storage container.
Barron said it took lab members time to learn to use the protocol efficiently, “but now they can get their samples in 5 to 10 minutes.” He’s sure other labs can and will enhance the technique for their own circumstances. He noted a poster presented at the Ninth Guadalupe Workshop on the proper handling of carbon nanotubes earned recognition and discussion among the world’s premier researchers in the field, noting the importance of the work for agencies in general.
“When we decided to write about this, we were originally just going to put it on the web and hope somebody would read it occasionally,” Barron said. “We couldn’t imagine who would publish it, but we heard that an editor at Springer Nature was really keen to have published articles like this.
“I think this is something people will use,” he said. “There’s nothing outrageous but it helps everybody, from high schools and colleges that are starting to use nanoparticles for experiments to small companies. That was the goal: Let’s provide a process that doesn’t cost thousands of dollars to install and allows you to transfer nanomaterials safely and on a large scale. Finally, publish said work in an open-access journal to maximize the reach across the globe.”
Just when I thought I’d seen all the carbon nanotube abbreviations; I find two new ones in my first news bit about adhesion. Later, I’m including a second news bit that has to do with the upcoming American Chemical Society (ACS) Meeting in San Diego, California.
Sticky carbon nanotubes (CNTs)
Scientists have developed an adhesive that retains its stickiness in extreme temperatures according to a July 10, 2019 news item on Nanowerk (Note: A link has been removed),
In very hot or cold environments, conventional tape can lose its stickiness and leave behind an annoying residue. But while most people can avoid keeping taped items in a hot car or freezer, those living in extreme environments such as deserts and the Antarctic often can’t avoid such conditions.
Now, researchers reporting in ACS’ journal Nano Letters (“Continuous, Ultra-lightweight, and Multipurpose Super-aligned Carbon Nanotube Tapes Viable over a Wide Range of Temperatures”) say they have developed a new nanomaterial tape that can function over a wide temperature range.
In previous work, researchers have explored using nanomaterials, such as vertically aligned multi-walled carbon nanotubes (VA-MWNTs), to make better adhesive tapes. Although VA-MWNTs are stronger than conventional tapes at both high and low temperatures, the materials are relatively thick, and large amounts can’t be made cost-effectively.
These are my first vertically aligned multi-walled carbon nanotubes (VA-MWNTs) and superaligned carbon nanotubes (SACNTs). I was a little surprised that VA-MWNTs didn’t include the C since these are carbon nanotubes (CNTs) and there are other types of nanotubes. So, I searched and found that inclusion of the letter ‘C’ for carbon seems to be discretionary. Moving on.
… Kai Liu, Xide Li, Wenhui Duan, Kaili Jiang and coworkers wondered if they could develop a new type of tape composed of superaligned carbon nanotube (SACNT) films. As their name suggests, SACNTs are nanotubes that are precisely aligned parallel to each other, capable of forming ultrathin but strong yarns or films.
To make their tape, the researchers pulled a film from the interior of an array of SACNTs — similar to pulling a strip of tape from a roll. The resulting double-sided tape could adhere to surfaces through van der Waals interactions, which are weak electric forces generated between two atoms or molecules that are close together. The ultrathin, ultra-lightweight and flexible tape outperformed conventional adhesives, at temperatures ranging from -321 F to 1,832 F. Researchers could remove the tape by peeling it off, soaking it in acetone or burning it, with no noticeable residues. The tape adhered to many different materials such as metals, nonmetals, plastics and ceramics, but it stuck more strongly to smooth than rough surfaces, similar to regular tape. The SACNT tape can be made cost-effectively in large amounts. In addition to performing well in extreme environments, the new tape might be useful for electronic components that heat up during use, the researchers say.
American Chemical Society (ACS) National Meeting in San Diego, Aug. 25to 29, 2019: an invite to journalists
A July 18, 2019 ACS press release (received via email) announced their upcoming meeting and it included an invitation to journalists. (ACS has two meetings per year, one on the East Coast and the other on the West, roughly speaking).
Materials science and nanotechnology topics at the upcoming 2019 American Chemical Society national meeting in San Diego
WASHINGTON, July 18, 2019 — Journalists who register for the American Chemical Society’s (ACS’) Fall 2019 National Meeting & Exposition in San Diego will have access to more than 9,500 presentations on the meeting’s theme, “Chemistry & Water,” will include nanotechnology and materials science topics. The meeting, one of the largest scientific conferences of the year, will be held Aug. 25 to 29  in San Diego.
Nobel Prize winner Frances Arnold, Ph.D., of the California Institute of Technology and Thomas Markland, DPhil, of Stanford University will deliver the two Kavli Foundation lectures on Aug. 26 .
The more than 9,500 presentations will include presentations on nanotechnology and materials science, such as:
Colloids and nanomaterials for water purification Nanozymes for bioanalysis and beyond The latest in wearable and implantable sensors Nanoscale and molecular assemblies: designing matter to control energy transport Colloidal quantum dots for solar and other emerging technologies Nanoscience of bourbon Targeted delivery of nanomedicines Advances in nanocellulose research for engineered functionality Water sustainability through nanotechnology
ACS will operate a press center with press conferences, a news media workroom fully staffed to assist in arranging interviews and free Wi-Fi, computers and refreshments.
Embargoed copies of press releases and a press conference schedule will be available in mid-August. Reporters planning to cover the meeting from their home bases will have access to the press conferences on YouTube at http://bit.ly/acs2019sandiego.
ACS considers requests for press credentials and complimentary registration to national meetings from reporters (staff and freelance) and public information officers at government, non-profit and educational institutions. See the website for details.
The ACS provides complimentary registration to national meetings to reporters (staff and freelancers) and public information officers from government, non-profit and educational institutions. Marketing and public relations professionals, lobbyists and scientists do not qualify as press and must register via the main meeting registration page. Journal managing editors, book commissioning editors, acquisitions editors, publishers and those who do not produce news for a publication or institution also do not qualify. We reserve the right to refuse press credentials for any reason.
No bloggers, eh? it’s been a long time since I’ve seen a press registration process that doesn’t mention bloggers at all.
Increasing awareness of bioeffects and toxicity of nanomaterials interacting with cells puts in focus the mechanisms by which nanomaterials can cross lipid membranes. Apart from well-discussed energy-dependent endocytosis for large objects and passive diffusion through membranes by solute molecules, there can exist other transport mechanisms based on physical principles. Based on this hypothesis, the team of theoretical physics at Universitat Rovira i Virgili in Tarragona, led by Dr. Vladimir Baulin, designed a research project to investigate the interaction between nanotube and lipid membranes. In computer simulations, the researchers studied what they call a “model bilayer”, composed only by one type of lipids. Based on their calculations, the team of Dr. Baulin observed that ultra -short nanotube (10nm length) can insert perpendicularly to the lipid bilayer core.
They observed that these nanotubes stay trapped in the cell
membrane, as commonly accepted by the scientific community. But a
surprise appears when they stretched their model cell membrane, then
inserted nanotubes which were trapped in the bilayer, suddenly started
to escape from the bilayer on both sides. This means that it is possible
to control the transport of nanomaterial across a cell membrane by
tuning the membrane tension.
This is where Dr. Baulin contacted Dr. Jean-Baptiste Fleury at the
Saarland University (Germany) to confirm this mechanism and to study
experimentally this tension-mediated transport phenomena. Dr. Fleury and
his team, designed a microfluidic experiment with a well-controlled
phospholipid bilayer, an experimental model for cell membranes and added
ultra-small carbon nanotubes (10nm in length) in solution. The
nanotubes had an adsorbed lipid monolayer that guarantees their stable
dispersion and prevent their clustering. Using a combination of optical
fluorescent microscopy and electrophysiological measurements, the team
of Dr. Fleury could follow individual nanotube crossing a bilayer and
unravel their pathway on a molecular level. And as predicted by the
simulations, they observed that nanotubes inserted into the bilayer by
dissolving their lipid coating into the artificial membrane. When a
tension of 4mN/m was applied to the bilayer, nanotubes spontaneously
escaped the bilayer just in few milliseconds, while at lower tensions
nanotubes remain trapped inside the membrane.
This discovery of translocation of tiny nanotubes through barriers
protecting cells, i.e. lipid bilayer, may raise concerns about safety of
nanomaterials for public health and suggest new mechanical mechanisms
to control the drug delivery.
The monitoring of air contamination by engineered nanomaterials (ENM) is a complex process with many uncertainties and limitations owing to the presence of particles of nanometric size that are not ENMs, the lack of validated instruments for breathing zone measurements and the many indicators to be considered.
In addition, some organizations, France’s Institut national de recherche et de sécurité (INRS) and Québec’s Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) among them, stress the need to also sample surfaces for ENM deposits.
In other words, to get a better picture of the risks of worker exposure, we need to fine-tune the existing methods of sampling and characterizing ENMs and develop new one. Accordingly, the main goal of this project was to develop innovative methodological approaches for detailed qualitative as well as quantitative characterization of workplace exposure to ENMs.
A PDF of the 88-page report is available in English or in French.
An August 30, 2018 (?) abstract of the IRSST report titled An Assessment of Methods of Sampling and Characterizing Engineered Nanomaterials in the Air and on Surfaces in the Workplace (2nd edition) by Maximilien Debia, Gilles L’Espérance, Cyril Catto, Philippe Plamondon, André Dufresne, Claude Ostiguy, which originated the news item, outlines what you can expect from the report,
This research project has two complementary parts: a laboratory investigation and a fieldwork component. The laboratory investigation involved generating titanium dioxide (TiO2) nanoparticles under controlled laboratory conditions and studying different sampling and analysis devices. The fieldwork comprised a series of nine interventions adapted to different workplaces and designed to test a variety of sampling devices and analytical procedures and to measure ENM exposure levels among Québec workers.
The methods for characterizing aerosols and surface deposits that were investigated include: i) measurement by direct-reading instruments (DRI), such as condensation particle counters (CPC), optical particle counters (OPC), laser photometers, aerodynamic diameter spectrometers and electric mobility spectrometer; ii) transmission electron microscopy (TEM) or scanning transmission electron microscopy (STEM) with a variety of sampling devices, including the Mini Particle Sampler® (MPS); iii) measurement of elemental carbon (EC); iv) inductively coupled plasma mass spectrometry (ICP-MS) and (v) Raman spectroscopy.
The workplace investigations covered a variety of industries (e.g., electronics, manufacturing, printing, construction, energy, research and development) and included producers as well as users or integrators of ENMs. In the workplaces investigated, we found nanometals or metal oxides (TiO2, SiO2, zinc oxides, lithium iron phosphate, titanate, copper oxides), nanoclays, nanocellulose and carbonaceous materials, including carbon nanofibers (CNF) and carbon nanotubes (CNT)—single-walled (SWCNT) as well as multiwalled (MWCNT).
The project helped to advance our knowledge of workplace assessments of ENMs by documenting specific tasks and industrial processes (e.g., printing and varnishing) as well as certain as yet little investigated ENMs (nanocellulose, for example).
Based on our investigations, we propose a strategy for more accurate assessment of ENM exposure using methods that require a minimum of preanalytical handling. The recommended strategy is a systematic two-step assessment of workplaces that produce and use ENMs. The first step involves testing with different DRIs (such as a CPC and a laser photometer) as well as sample collection and subsequent microscopic analysis (MPS + TEM/STEM) to clearly identify the work tasks that generate ENMs. The second step, once work exposure is confirmed, is specific quantification of the ENMs detected. The following findings are particularly helpful for detailed characterization of ENM exposure:
The first conclusive tests of a technique using ICP-MS to quantify the metal oxide content of samples collected in the workplace
The possibility of combining different sampling methods recommended by the National Institute for Occupational Safety and Health (NIOSH) to measure elemental carbon as an indicator of NTC/NFC, as well as demonstration of the limitation of this method stemming from observed interference with the black carbon particles required to synthesis carbon materials (for example, Raman spectroscopy showed that less than 6% of the particles deposited on the electron microscopy grid at one site were SWCNTs)
The clear advantages of using an MPS (instead of the standard 37-mm cassettes used as sampling media for electron microscopy), which allows quantification of materials
The major impact of sampling time: a long sampling time overloads electron microscopy grids and can lead to overestimation of average particle agglomerate size and underestimation of particle concentrations
The feasibility and utility of surface sampling, either with sampling pumps or passively by diffusion onto the electron microscopy grids, to assess ENM dispersion in the workplace
These original findings suggest promising avenues for assessing ENM exposure, while also showing their limitations. Improvements to our sampling and analysis methods give us a better understanding of ENM exposure and help in adapting and implementing control measures that can minimize occupational exposure.