Tag Archives: Swiss Federal Institute of Technology Zurich

ATMs (automated teller machines) fend off attackers with biomimicry and nanoparticles

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Attack an ATM (automated teller machine) and you will be in peril one day soon, if Swiss researchers at ETH Zurich (Swiss Federal Institute of Technology in Zurich) have their way. An April 11, 2014 news item on Nanowerk describes the inspiration,

Hot foam may soon send criminals running if they damage [an] ATM. ETH researchers have developed a special film that triggers an intense reaction when destroyed. The idea originates from a beetle that uses a gas explosion to fend off attackers.

An April 11, 2014 ETH Zurich news release (also on EurekAlert), which originated the news, item, provides more details about the insect inspiring this new approach to protecting ATMs and information about the increase of ATM attacks,

Its head and pronotum are usually rusty red, and its abdomen blue or shiny green: the bombardier beetle is approximately one centimetre long and common to Central Europe. At first glance, it appears harmless, but it possesses what is surely the most aggressive chemical defence system in nature. When threatened, the bombardier beetle releases a caustic spray, accompanied by a popping sound. This spray can kill ants or scare off frogs. The beetle produces the explosive agent itself when needed. Two separately stored chemicals are mixed in a reaction chamber in the beetle’s abdomen. An explosion is triggered with the help of catalytic enzymes.

“When you see how elegantly nature solves problems, you realise how deadlocked the world of technology often is,” says Wendelin Jan Stark, a professor from the ETH Department of Chemistry and Applied Biosciences. He and his team therefore looked to the bombardier beetle for inspiration and developed a chemical defence mechanism designed to prevent vandalism – a self-defending surface composed of several sandwich-like layers of plastic. If the surface is damaged, hot foam is sprayed in the face of the attacker. This technology could be used to prevent vandalism or protect valuable goods. “This could be used anywhere you find things that shouldn’t be touched,” said Stark. In agriculture and forestry, for example, it could be used to keep animals from gnawing on trees.

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The newly developed film may be particularly well suited to protecting ATMs or cash transports, write the researchers in their paper published in the Journal of Materials Chemistry A. In ATMs, banknotes are kept in cash boxes, which are exchanged regularly. The Edinburgh-based European ATM Security Team reports that the number of attacks on ATMs has increased in recent years. During the first half of 2013, more than 1,000 attacks on ATMs took place in Europe, resulting in losses of EUR 10 million.

While protective devices that can spray robbers and banknotes already exist, these are mechanical systems, explains Stark. “A small motor is set in motion when triggered by a signal from a sensor. This requires electricity, is prone to malfunctions and is expensive.” The objective of his research group is to replace complicated control systems with cleverly designed materials.

More technical information about the films and about an earlier project applying a similar technology to seeds is offered in the news release,

The researchers use plastic films with a honeycomb structure for their self-defending surface. The hollow spaces are filled with one of two chemicals: hydrogen peroxide or manganese dioxide. The two separate films are then stuck on top of each another. A layer of clear lacquer separates the two films filled with the different chemicals. When subjected to an impact, the interlayer is destroyed, causing the hydrogen peroxide and manganese dioxide to mix. This triggers a violent reaction that produces water vapour, oxygen and heat. Whereas enzymes act as catalysts in the bombardier beetle, manganese dioxide has proven to be a less expensive alternative for performing this function in the lab.

The researchers report that the product of the reaction in the film is more of a foam than a spray when compared to the beetle, as can be seen in slow motion video footage. Infrared images show that the temperature of the foam reaches 80 degrees. Just as in nature, very little mechanical energy is required in the laboratory to release a much greater amount of chemical energy – quite similar to a fuse or an electrically ignited combustion cycle in an engine.

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To protect the cash boxes, the researchers prepare the film by adding manganese dioxide. They then add a dye along with DNA enveloped in nanoparticles. If the film is destroyed, both the foam and the dye are released, thereby rendering the cash useless. The DNA nanoparticles that are also released mark the banknotes so that their path can be traced. Laboratory experiments with 5 euro banknotes have shown that the method is effective. The researchers write that the costs are also reasonable and expect one square meter of film to cost approximately USD 40.

In a similar earlier project, ETH researchers developed a multi-layer protective envelope for seed that normally undergoes complex chemical treatment. Researchers emulated the protective mechanism of peaches and other fruit, which releases toxic hydrogen cyanide to keep the kernels from being eaten. Wheat seeds are coated with substances that also form hydrocyanic acid when they react. However, the base substances are separated from each other in different layers and react only when the seeds are bitten by a herbivore. Stark describes the successful research method as “imitating nature and realising simple ideas with high-tech methods.”

Here are links to and citations for both research papers (ATM & seeds),

Self-defending anti-vandalism surfaces based on mechanically triggered mixing of reactants in polymer foils by Jonas G. Halter, Nicholas H. Cohrs, Nora Hild, Daniela Paunescu, Robert N. Grass, and Wendelin Jan Stark. J. Mater. Chem. A, 2014, DOI: 10.1039/C3TA15326F First published online 07 Mar 2014

Induced cyanogenesis from hydroxynitrile lyase and mandelonitrile on wheat with polylactic acid multilayer-coating produces self-defending seeds by Jonas G. Halter, Weida D. Chen, Nora Hild, Carlos A. Mora, Philipp R. Stoessel, Fabian M. Koehler, Robert N. Grass, and Wendelin J. Stark. J. Mater. Chem. A, 2014,2, 853-858 DOI: 10.1039/C3TA14249C
First published online 03 Dec 2013

The ‘anti-vandalism’ paper is open access but the ‘cyanogenesis’ paper is not. As for the beetle who inspired this work, here’s an image of one courtesy of ETH,

The bombardier beetle inspired the researchers of ETH Zurich. (Photo: jayvee18 – Fotolia)

The bombardier beetle inspired the researchers of ETH Zurich. (Photo: jayvee18 – Fotolia)

It looks rather pretty with its hard green (iridescent?) back shell.

Silver nanoparticles: we love you/we hate you

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We seem to have a love/hate affair with silver nanoparticles. Long recognized as biocides capable of killing bacteria, silver nanoparticles are used both in hospital settings and in sports wear. As the use of silver nanoparticles increases, there are concerns about unintended consequences to the environment and to human health. An Apr. 12, 2013 news item on Nanowerk highlights some research done in Europe in 2011 (Note: Links have been removed),

As part of an EU funded project called Prosuite, Walser [Tobias Walser, researcher at the Institute for environmental engineering at the Swiss Federal Institute of Technology Zürich {ETH}] and colleagues analysed the environmental impact of nanosilver T-shirts during their entire life cycle, from raw material extraction to end-of-life disposal (“Prospective Environmental Life Cycle Assessment of Nanosilver T-Shirts”). This, according to Walser, is the first of its kind for a nanomaterial. The scientists found that the T-shirt’s environmental impact during use would be reduced if they are washed less often than conventional ones, due to their antimicrobial properties. This would even compensate for a slightly higher climate footprint during production. Walser explains: “In comparison to all toxic releases during the life cycle of a T-shirt, the toxic releases from nanosilver from washing appear to be of minor relevance.” [emphasis mine]

The Apr. 11, 2013 article by Constanze Böttcher for Youris.com, which originated the news item, expands on the theme of toxicity, nanosilver, and wastewater (Note: A link has been removed),

Previous studies looked at single impacts of antibacterial textiles. For example, scientists found that nanosilver leaches into the wastewater during washing. According to other studies, this silver may not be that harmful to the environment because it is transformed into a nearly insoluble substance called silver sulphide in wastewater treatments. A study published by the Danish Environmental Protection Agency in 2012 did not find “specific risks” to health or environmental effects of nanosilver textiles available in Denmark.

This finding contrasts with more recent research at Duke University’s CEINT (Center for Environmental Implications of Nanotechnology) mesocosm project where a study did point to adverse responses (noted in my Feb. 28, 2013 posting where I highlighted two nanosilver environmental studies, a Finnish/Estonian research project and the CEINT project),

In experiments mimicking a natural environment, Duke University researchers have demonstrated that the silver nanoparticles used in many consumer products can have an adverse effect on plants and microorganisms.

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The main route by which these particles enter the environment is as a by-product of water and sewage treatment plants. [emphasis] The nanoparticles are too small to be filtered out, so they and other materials end up in the resulting “sludge,” which is then spread on the land surface as a fertilizer.

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The researchers found that one of the plants studied, a common annual grass known as Microstegium vimeneum, had 32 percent less biomass in the mesocosms treated with the nanoparticles. Microbes were also affected by the nanoparticles, Colman [Benjamin Colman, a post-doctoral fellow in Duke’s biology department and a member of the Center for the Environmental Implications of Nanotechnology (CEINT)] said. One enzyme associated with helping microbes deal with external stresses was 52 percent less active, while another enzyme that helps regulate processes within the cell was 27 percent less active. The overall biomass of the microbes was also 35 percent lower, he said.

As I’ve suggested before, analysing the impact that new products and materials may have on the environment and on our health is a complex process.  From Böttcher’s 2013 article (Note: Links have been removed),

Some experts are concerned about their environmental risks, however. The study “is very relevant” because it “gives a fingerprint” about the impact of such T-shirts, Anders Baun says. But the professor in risk assessment of nanomaterials at the department of environmental engineering at the Technical University of Denmark, based in Lyngby, considers it “a bad idea to distribute silver in the environment”. He points to a study that found evidence for nanosilver accumulating in the food web based on a study of plants and animals of an experimental wetland environment. Moreover, he says, it is unknown how the coating of nanosilver influences its environmental behaviour. Baun has previously criticised the European policies regarding nanosilver and is currently enrolled in a scientific committee on the topic as invited expert. The expert group will publish its opinion later this year, he says.

There’s also the possibility that bacteria will develop resistance with increased use of silver nanoparticles in medical environments and in sportswear and in other applications.

For those who want to conduct their own investigations, here’s a link to and a citation for Walser’s 2011 paper,

Prospective Environmental Life Cycle Assessment of Nanosilver T-Shirts by Tobias Walser, Evangelia Demou, Daniel J. Lang, and Stefanie Hellweg.  Environ. Sci. Technol [Environmental Science and Technology], 2011, 45 (10), pp 4570–4578 DOI: 10.1021/es2001248 Publication Date (Web): April 20, 2011
Copyright © 2011 American Chemical Society

This paper is open access.

A description of PROSUITE (PROspective SUstaInability assessment of TEchnologies project) can be found here and the PROSUITE project website can found here.

ETA Apr. 18, 2013: An Apr. 18, 2013 news item (Barely any nanosilver from consumer products in the water) on Nanowerk provides some insight into why at least one European country views the presence of silver nanoparticles in sewage sludge without any particular alarm,

The study did not examine what happens to nanosilver in the sewage sludge thereafter. In Switzerland, it is not permissible to use sewage sludge on farmland, and most of the sludge is therefore burned. [emphasis mine] The heavy metals separated in this process should not be released into the environment in large quantities.

Here’s a link to and citation for the Swiss study,

Fate and transformation of silver nanoparticles in urban wastewater systems by Ralf Kaegia, Andreas Voegelina, Christoph Orta, Brian Sinneta, Basilius Thalmanna, Jasmin Krismerb, Harald Hagendorferc, Maline Elumelua, and Elisabeth Muellerd. Water Research, http://dx.doi.org/10.1016/j.watres.2012.11.060 Available online 26 March 2013

The article is behind a paywall.

Bend it, twist it, roll it—composites inspired by nature

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Researchers at ETH (Swiss Federal Institute of Technology) Zurich have developed a new composite material with bioinspired microstructures, from the Apr. 16, 2013 news item on Nanowerk,

Plant components that bend, roll or twist in response to external stimuli such as temperature or moisture are fairly commonplace in nature and often play a role in the dispersal of seeds. Pine cones, for instance, close their scales when wet and open them again once they have dried out. André Studart, a professor of complex materials at ETH Zurich’s Department of Materials, and his group have now applied the knowledge of how these movements come about to produce synthetically a composite material with comparable properties …

The Apr. 16, 2013 ETH Zurich news article by Maja Schaffner, which originated the news item, goes on to describe how the pine cone comes by its abilities,

Studart and co-workers knew from the literature how pine cone scales work: two firmly connected layers lying on top of each other inside a scale are responsible for the movement. Although the two layers consist of the same swellable material, they expand in different ways under the influence of water because of the rigid fibres enclosed in the layers. In each of the layers, these are specifically aligned, thus determining the direction of expansion. Therefore, when wet only one of the two layers expands in the longitudinal direction of the scale and bends on the other side.

The scientists then devised an artificial means of achieving the pine cone’s ability to swell in two orientations (from the article),

Inspired by nature, the scientists began to produce a similar moving material in the lab by adding ultrafine aluminium oxide platelets as the rigid component to gelatine – the swellable base material – and pouring it into square moulds. The surface of the aluminium oxide platelets is pre-coated with iron oxide nanoparticles to make them magnetic. This enabled the researchers to align the platelets in the desired direction using a very weak rotating magnetic field. On the cooled and hardened first layer, they poured a second one with the same composition, differing only in the direction of the rigid elements.

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The scientists cut this double-layered material into strips. Depending on the direction in which these strips were cut compared to the direction of the rigid elements in the gelatine pieces, the strips bent or twisted differently under the influence of moisture: some coiled lengthwise like a pig’s tail, others turned loosely or very tightly on their own axis to form a helix reminiscent of spiral pastries. “Meanwhile, we can programme the way in which a strip should take shape fairly accurately,” explains Studart.

The researchers also produced longer strips that behave differently in different sections – curl in the first section, for instance, then bend in one direction and the other in the final section. Or they created strips that expanded differently length and breadthwise in different sections in water. And they also made strips from another polymer that responded to both temperature and moisture – with rotations in different directions.

However, Studart was most interested in rotational movements (from the article),

“Bending movements,” he says, “are relatively straightforward.” Metallic bilayer compounds that bend upon temperature changes are widely used in thermostats, for instance. The new method, however, is largely material-independent, which means that any material that responds to external stimuli – and, according to Studart, there are quite a few – can potentially be rendered self-shaping. “Even the solid component is freely selectable and can be made magnetically responsive through the iron-oxide coating,” he says.

Here’s a link to and a citation for the article,

Self-shaping composites with programmable bioinspired microstructures by Randall M. Erb, Jonathan S. Sander, Roman Grisch, & André R. Studart. Nature Communications 4, Article number: 1712 doi:10.1038/ncomms2666 Published 16 April 2013

This article is behind a paywall.

According to Schaffner’s article, Studart believes this work could have applications in the field of medical devices and for self-shaping ceramic devices.

Where do all those particles go or what does degradable mean at the nanoscale?

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Scientists at Switzerland’s ETH Zurich (Swiss Federal Institute of Technology Zurich) note that cerium oxide nanoparticles do not degrade. From the May 21, 2012 article by Simone Ulmer on the ETH Zurich website,

Tiny particles of cerium oxide do not burn or change in the heat of a waste incineration plant. They remain intact on combustion residues or in the incineration system, as a new study by researchers from ETH Zurich reveals.

Over 100 million tons of waste are incinerated worldwide every year. Due to the increasing use of nanoparticles in construction materials, paints, textiles and cosmetics, for instance, nanoparticles also find their way into incineration plants. What happens to them there, however, had not been investigated until now. Three ETH-Zurich teams from fields of chemistry and environmental engineering thus set about finding out what happens to synthetic nano-cerium oxide during the incineration of refuse in a waste incineration plant. Cerium oxide itself is a non-toxic ceramic material, not biologically degradable and a common basic component in automobile catalytic converters and diesel soot filters.

Here’s their reasoning (from Ulmer’s article),

Experts fear that non-degradable nanomaterials might be just as harmful for humans and the environment as asbestos. As yet, however, not enough is known about the properties of nanomaterials (see ETH Life, 25 March 2010). One thing is for sure: they differ greatly from larger particles of the same material. Nanoparticles are more mobile and have a different surface structure. Knowledge of these properties is important with the increasing use of nanomaterials as, as they are transferred through incineration plants or sewage, and as they are absorbed by people in food (see ETH Life, 15 July 2008) and perhaps even through the skin and respiration, and can thus enter the body. [emphases mine]

Recent research suggests that there are many, many naturally occurring nanoparticles which we and other living beings have been innocently ingesting for millenia as noted in my Feb. 9, 2012 posting and my Nov. 24, 2011 posting. More recently, Dr. Andrew Maynard at his 2020 Science blog posted about carbon nanoparticles, which are  ubiquitous. From Andrew’s May 19, 2012 posting,

This latest paper was published in the journal Science Progress a few weeks ago, and analyzes the carbon nanoparticle content of such everyday foods as bread, caramelized sugar, corn flakes and biscuits.  The authors found that products containing caramelized sugar – including baked goods such as bread – contained spherical carbon nanoparticles in the range 4 – 30 nm (with size being associated with the temperature of caramelization).

Getting back to the cerium oxide project, here’s what the Swiss scientists found (from Ulmer’s article),

The researchers’ tests revealed that cerium oxide does not change significantly during incineration. The fly-ash separation devices proved extremely efficient: the scientists did not find any leaked cerium oxide nanoparticles in the waste incineration plant’s clean gas. That said, the nanoparticles remained loosely bound to the combustion residues in the plant and partially in the incineration system, too. The fly ash separated from the flue gas also contained cerium oxide nanoparticles.

Nowadays, combustion residues – and thus the nanoparticles bound to them – end up on landfills or are reprocessed to extract copper or aluminium, for instance. The researchers see a need for action here. “We have to make sure that new nanoparticles don’t get into the water and food cycle via landfills or released into the atmosphere through further processing measures,” says Wendelin Stark, head of the study and a professor of chemical engineering at ETH Zurich. Moreover, the fact that nanoparticles that could be inhaled if inadequate protection is worn might be present in the incineration system needs to be taken into consideration during maintenance work.

I have a couple questions for the researchers. First, is nanoscale cerium dioxide dangerous and do you have any studies?  Second, does anything ever degrade? As I recall (dimly), matter cannot be destroyed. Are they trying to break down the nanoscale cerium oxide to a smaller scale? And, what would the impact be then?

All in all, this is very interesting research to me as it has raised some questions in a way I had not previously considered. Thanks to Nanowerk where I found the May 24, 2012 news item that alerted me to the article.