Tag Archives: Van Der Waals Forces

Research into the properties of water at the nanoscale and water droplet networks

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I have two pieces of research with the only common element being water. First, there’s a May 9, 2014 news release on EurekAlert issued by the Politecnico di Torino (Italy; rough translation: Turin Polytechnic),

Swimming in a honey pool. That’s the sensation a water molecule should “feel” while approaching a solid surface within a nanometer (i.e. less than a ten-thousandth of hair diameter). The reduction in water mobility in the very close proximity of surfaces at the nanoscale is the well-known phenomenon of “nanoconfinement”, and it is due to both electrostatic and van der Waals attractive forces ruling matter interactions at that scale.

In this context, scientists from Politecnico di Torino and Houston Methodist Research Institute have taken a further step forward, by formulating a quantitative model and a physical interpretation able of predicting the nanoconfinement effect in a rather general framework. In particular, geometric and chemical characteristics as well as physical conditions of diverse nanoconfining surfaces (e.g. proteins, carbon nanotubes, silica nanopores or iron oxide nanoparticles) have been quantitatively related to mobility reduction and “supercooling” conditions of water, namely the persistence of water in a liquid state at temperatures far below 0°C, when close to a solid surface.

This result has been achieved after two years of in silico (i.e. computer-based) and in vitro (i.e. experiment-driven) activities by Eliodoro Chiavazzo, Matteo Fasano, Pietro Asinari (Multi-Scale Modelling Lab, Department of Energy at Politecnico di Torino) and Paolo Decuzzi (Center for the Rational Design of Multifunctional Nanoconstructs at Houston Methodist Research Institute).

I love the image of swimming in a ‘honey pool’ and while developing a schema for predicting a nanoconfinement effect may not seem all that exciting to an outsider the applications are varied according to the news release,

This study may soon find applications in the optimization and rational design of a broad variety of novel technologies ranging from applied physics (e.g. “nanofluids”, suspensions made out of water and nanoparticles for enhancing heat transfer) to sustainable energy (e.g. thermal storage based on nanoconfined water within sorbent materials); from detection and removal of pollutant from water (e.g. molecular sieves) to nanomedicine.

In fact this work is finding an immediate application in the field of medicine as pertaining to magnetic resonance imaging (MRI), from the news release,

The latter is the field where the research has indeed found a first important application. Every year, almost sixty millions of Magnetic Resonance Imaging (MRI) scans are performed, with diagnostic purposes. In the past decade, MRI technology benefitted from various significant scientific advances, which allowed more precise and sharper images of pathological tissues. Among other, contrast agents (i.e. substances used for improving contrast of structures or fluids within the body) importantly contributed in enhancing MRI performances.

This research activity has been able to explain and predict the increase in MRI performances due to nanoconfined contrast agents, which are currently under development at the Houston Methodist Research Institute. Hence, the discovery paves the way to further increase in the quality of MRI images, in order to possibly improve chances of earlier and more accurate detection of diseases in millions of patients, every year.

Here’s a link to and a citation for the research paper,

Scaling behaviour for the water transport in nanoconfined geometries by Eliodoro Chiavazzo, Matteo Fasano, Pietro Asinari & Paolo Decuzzi. Nature Communications 5 Article number: 4565 doi:10.1038/ncomms4565 Published 03 April 2014

This is an open access paper and, unusually, I am excerpting the Abstract as I find it helps to further explain this work (although the more technical aspects are lost on me),

The transport of water in nanoconfined geometries is different from bulk phase and has tremendous implications in nanotechnology and biotechnology. Here molecular dynamics is used to compute the self-diffusion coefficient D of water within nanopores, around nanoparticles, carbon nanotubes and proteins. For almost 60 different cases, D is found to scale linearly with the sole parameter θ as D(θ)=DB[1+(DC/DB−1)θ], with DB and DC the bulk and totally confined diffusion of water, respectively. The parameter θ is primarily influenced by geometry and represents the ratio between the confined and total water volumes. The D(θ) relationship is interpreted within the thermodynamics of supercooled water. As an example, such relationship is shown to accurately predict the relaxometric response of contrast agents for magnetic resonance imaging. The D(θ) relationship can help in interpreting the transport of water molecules under nanoconfined conditions and tailoring nanostructures with precise modulation of water mobility.

The second piece of ‘water’ research was featured in a May 13, 2014 news item on Nanowerk,

A simple new technique to form interlocking beads of water in ambient conditions could prove valuable for applications in biological sensing, membrane research and harvesting water from fog.

Researchers at the Department of Energy’s Oak Ridge National Laboratory have developed a method to create air-stable water droplet networks known as droplet interface bilayers. These interconnected water droplets have many roles in biological research because their interfaces simulate cell membranes. Cumbersome fabrication methods, however, have limited their use.

A May 13, 2014 Oak Ridge National Laboratory (ORNL) news release, which originated the news item, provides more details,

“The way they’ve been made since their inception is that two water droplets are formed in an oil bath then brought together while they’re submerged in oil,” said ORNL’s Pat Collier, who led the team’s study published in the Proceedings of the National Academy of Sciences. “Otherwise they would just pop like soap bubbles.”

Instead of injecting water droplets into an oil bath, the ORNL research team experimented with placing the droplets on a superhydrophobic surface infused with a coating of oil. The droplets aligned side by side without merging.

To the researchers’ surprise, they were also able to form non-coalescing water droplet networks without including lipids in the water solution. Scientists typically incorporate phospholipids into the water mixture, which leads to the formation of an interlocking lipid bilayer between the water droplets.

“When you have those lipids at the interfaces of the water drops, it’s well known that they won’t coalesce because the interfaces join together and form a stable bilayer,” ORNL coauthor Jonathan Boreyko said. “So our surprise was that even without lipids in the system, the pure water droplets on an oil-infused surface in air still don’t coalesce together.”

The team’s research revealed how the unexpected effect is caused by a thin oil film that is squeezed between the pure water droplets as they come together, preventing the droplets from merging into one. Watch a video of the process on ORNL’s YouTube channel.

With or without the addition of lipids, the team’s technique offers new insight for a host of applications. Controlling the behavior of pure water droplets on oil-infused surfaces is key to developing dew- or fog-harvesting technology as well as more efficient condensers, for instance.

“Our finding of this non-coalescence phenomenon will shed light on these droplet-droplet interactions that can occur on oil-infused systems,” Boreyko said.

The ability to create membrane-like water droplet networks by adding lipids leads to a different set of functional applications, Collier noted.

“These bilayers can be used in anything from synthetic biology to creating circuits to bio-sensing applications,” he said. “For example, we could make a bio-battery or a signaling network by stringing some of these droplets together. Or, we could use it to sense the presence of airborne molecules.”

The team’s study also demonstrated ways to control the performance and lifetime of the water droplets by manipulating oil viscosity and temperature and humidity levels.

Here’s another link to the paper and a citation,

Air-stable droplet interface bilayers on oil-infused surfaces by Jonathan B. Boreyko, Georgios Polizos, Panos G. Datskos, Stephen A. Sarles, and C. Patrick Collier.  PNAS 2014 ; published ahead of print May 12, 2014, doi: 10.1073/pnas.1400381111

This paper is behind a paywall.

Staying stuck when it’s wet; learning from the geckos

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Researchers from the University of Akron have published another study on geckos and their ‘stickability’ in watery environments. Last mentioned here in my Aug. 10, 2012 posting, doctoral candidate Alyssa Stark  and her colleagues were then testing the geckos by placing them on wetted glass plate surfaces and also by immersing them on water-filled tubs with glass bottom,

Next, the trio sprayed the glass plate with a mist of water and retested the lizards, but this time the animals had problems holding tight: the attachment force varied each time they took a step. The droplets were interfering with the lizards’ attachment mechanism, but it wasn’t clear how. And when the team immersed the geckos in a bath of room temperature water with a smooth glass bottom, the animals were completely unable to anchor themselves to the smooth surface. ‘The toes are superhydrophobic [water repellent]’, explains Stark, who could see a silvery bubble of air around their toes, but they were unable to displace the water surrounding their feet to make the tight van der Waals contacts that usually keep the geckos in place.

Then, the team tested the lizard’s adhesive forces on the dry surface when their feet had been soaking for 90 min and found that the lizards could barely hold on, detaching when they were pulled with a force roughly equalling their own weight. ‘That might be the sliding behaviour that we see when the geckos climb vertically up misted glass’, says Stark. So, geckos climbing on wet surfaces with damp feet are constantly on the verge of slipping and Stark adds that when the soggy lizards were faced with the misted and immersed horizontal surfaces, they slipped as soon as the rig started pulling.

In this latest research, from the Ap. 1, 2013 news release issued by the University of Akron on EurekAlert, Stark and her colleagues announce they’ve discovered the conditions under which geckos can adhere to wet surfaces,

Principal investigator Stark and her fellow UA researchers Ila Badge, Nicholas Wucinich, Timothy Sullivan, Peter Niewiarowski and Ali Dhinojwala study the adhesive qualities of gecko pads, which have tiny, clingy hairs that stick like Velcro to dry surfaces. In a 2012 study, the team discovered that geckos lose their grip on wet glass. This finding led the scientists to explore how the lizards function in their natural environments.

The scientists studied the clinging power of six geckos, which they outfitted with harnesses and tugged upon gently as the lizards clung to surfaces in wet and dry conditions. The researchers found that the effect of water on adhesive strength correlates with wettability, or the ability of a liquid to maintain contact with a solid surface. On glass, which has high wettability, a film of water forms between the surface and the gecko’s foot, decreasing adhesion. Conversely, on surfaces with low wettability, such as waxy leaves on tropical plants, the areas in contact with the gecko’s toes remain dry and adhesion, firm. [emphasis mine]

“The geckos stuck just as well under water as they did on a dry surface, as long as the surface was hydrophobic,” Stark explains. “We believe this is how geckos stick to wet leaves and tree trunks in their natural environment.”

For interested parties, this is where the paper can be found,

The discovery, “Surface Wettability Plays a Significant Role in Gecko Adhesion Underwater,” was published April 1, 2013 by the Proceedings of the National Academy of Sciences. The study has implications for the design of a synthetic gecko-inspired adhesive.

Here’s an image of a gecko (from the University of Akron’s webpage with their Ap. 1, 2013 news release),

Courtesy University of Akron [downloaded from http://www.uakron.edu/im/online-newsroom/news_details.dot?newsId=ec9fd559-e4af-487f-a9cc-2ea5f5c9612d&pageTitle=Top%20Story%20Headline&crumbTitle=Geckos%20keep%20firm%20grip%20in%20wet%20natural%20habitat]

Courtesy University of Akron [downloaded from http://www.uakron.edu/im/online-newsroom/news_details.dot?newsId=ec9fd559-e4af-487f-a9cc-2ea5f5c9612d&pageTitle=Top%20Story%20Headline&crumbTitle=Geckos%20keep%20firm%20grip%20in%20wet%20natural%20habitat]


Not mentioned in this news release, one of the relevant applications for this work would be getting bandages and dressings  to adhere to wet surfaces.

Eliminate deodorants and antiperspirants with 1940s gas mask technology

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A Mar. 19, 2013 news item on Nanowerk details a technology from UK company, Odegon Technologies, which could eliminate the use of deodorants and antiperspirants,

Underarm clothing tags which harness and store the molecules responsible for the smell of perspiration will be made available on the UK high street from March [2013].

The breakthrough invention from technical fabric innovators, Odegon Technologies, eliminates the unwanted smell resulting from human sweat via a small and discrete 7cm x 4cm fabric tag housing a three-dimensional mesh of highly absorbent material. The DeoTags will be discreetly sewn into the underarm of three suits and one blazer available nationwide and online by UK retailer, Marks & Spencer (M&S). As part of the retailer’s summer range, the tailoring offers consumers a unique solution to unwanted smells in the summer weather, and as such, could reduce dry cleaning costs and prolong the life of the garment.

Jasmin Malik Chua in a June 16, 2010 article for ecouterre about the product (called Odour Tags at the time) gives some technical information (Note:  A link has been removed),

Dubbed “Odour Tags,” the stink-eliminating patches are chemical-free, inert, odorless (naturally), and non-allergenic, according to the Shropshire, England-based firm. The tag can be integrated into the underarm area of the garment by clothing manufacturers or sold as an iron-on patch for application at home. In both cases, notes Odegon, the tag will remain permanently in place for the life of the clothing, no matter how many times it’s washed or dried.

… Made from nanoporous carbon, the surface area of the active inner material is composed of myriad peaks and troughs, which attract and trap odor molecules by Van der Waals forces until the garment is cleaned and the molecules are flushed out.Activated carbon itself has a storied history; it was patented in 1942 by the British Ministry of Defence for use in gas masks and CBRN (chemical, biological, radiological, and nuclear) protection suits.

I gather Odegon has changed its product name from Odour Tags to DeoTags. As for the company itself, the news item states that it was formed in 2010. You can find more information in Chua’s article (which is copiously illustrated), in the news item, or at the Odegon company website.

Make your carbon atoms stand taller to improve electronic devices

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Scientists from Ireland ((Tyndall National Institute at University College Cork [UCC]) and Singapore (National University of Singapore [NUS]) have jointly published a paper about how they achieved a ten-fold increase in the switching efficiency of electronic devices by changing one carbon atom. From the Jan. 21, 2013 news item on ScienceDaily,

These devices could provide new ways to combat overheating in mobile phones and laptops, and could also aid in electrical stimulation of tissue repair for wound healing.

The breakthrough creation of molecular devices with highly controllable electrical properties will appear in the February [2013] issue of Nature Nanotechnology. Dr. Damien Thompson at the Tyndall National Institute, UCC and a team of researchers at the National University of Singapore led by Prof. Chris Nijhuis designed and created the devices, which are based on molecules acting as electrical valves, or diode rectifiers.

Dr. Thompson explains, “These molecules are very useful because they allow current to flow through them when switched ON and block current flow when switched OFF. The results of the study show that simply adding one extra carbon is sufficient to improve the device performance by more than a factor of ten. We are following up lots of new ideas based on these results, and we hope ultimately to create a range of new components for electronic devices.” Dr. Thompson’s atom-level computer simulations showed how molecules with an odd number of carbon atoms stand straighter than molecules with an even number of carbon atoms. This allows them to pack together more closely. Tightly-packed assemblies of these molecules were formed on metal electrode surfaces by the Nijhuis group in Singapore and were found to be remarkably free of defects. These high quality devices can suppress leakage currents and so operate efficiently and reliably. The device can be cleanly switched on and off purely on the basis of the charge and shape of the molecules, just like in the biological nanomachines that regulate photosynthesis, cell division and tissue growth.

The Jan. ??, 2013 University College Cork news release, which originated the news item, provides more details,

The combined experiments and simulations show for the first time that minute improvements in molecule orientation and packing trigger changes in van der Waals forces that are sufficiently large to dramatically improve the performance of electronic devices. Dr. Thompson explains: “These van der Waals forces are the weakest of all intermolecular forces and only become significant when summed over large areas. Hence, up until now, the majority of research into ultra-small devices has used stronger “pi-pi” interactions to stick molecules together, and has ignored the much weaker, but ubiquitous, van der Waals interactions. The present study shows how van der Waals effects, which are present in every conceivable molecular scale device, can be tuned to optimise the performance of the device.”

The devices are based on molecules that act as diodes by allowing current to pass through them when operated at forward bias and blocking current when the bias is reversed. Molecular rectifiers were first proposed back in 1974, and advances in scientific computing have allowed molecular‐level design to be used over the past decade to develop new organic materials that provide better electrical responses. However, the relative importance of the interactions between the molecules, the nature of the molecule-metal contact and the influence of environmental effects have been questioned. This new research demonstrates that dramatic improvements in device performance may be achieved by controlling the van der Waals forces that pack the molecules together. Simply changing the number of carbon atoms by one provides significantly more stable and more reproducible devices that exhibit an order of magnitude improvement in ON/OFF ratio. The research findings demonstrate the feasibility of boosting device performances by creating tighter seals between molecules.

Here a citation and a link to the paper,

The role of van der Waals forces in the performance of molecular diodes by Nisachol Nerngchamnong, Li Yuan, Dong-Chen Qi, Jiang Li, Damien Thompson, & Christian A. Nijhuis. Nature Nanotechnology (2013) doi:10.1038/nnano.2012.238 Advance online publication: Jan. 6, 2013.

This paper is behind a paywall.

How do you make a harness for a gecko?

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It’s the first question (how do you make a harness for a gecko?) I had on reading the latest research about geckos and their ability to adhere to various surfaces, dry and wet. From the Aug. 9,2012 news item on Nanowerk,

But first they had to find out how well their geckos clung onto glass with dry feet. Fitting a tiny harness around the lizard’s pelvis and gently lowering the animal onto a plate of smooth glass, Stark [Alyssa Stark] and Sullivan [Timothy Sullivan] allowed the animal to become well attached before connecting the harness to a tiny motor and gently pull the lizard until it came unstuck. [emphasis mine] The geckos hung on tenaciously, and only came unstuck at forces of around 20N, which is about 20 times their own body weight. ‘The gecko attachment system is over-designed’, says Stark.

Here’s more about the research and the geckos (from the news item),

Geckos are remarkable little creatures, clinging to almost any dry surface, and Alyssa Stark, from the University of Akron, USA, explains that they appear to be equally happy scampering through tropical rainforest canopies as they are in urban settings. ‘A lot of work is done on geckos that looks at the very small adhesive structures on their toes to really understand how the system works at the most basic level’, says Stark. She adds that the animals grip surfaces with microscopic hairs on the soles of their feet that make close enough contact to be attracted to the surface by the minute van der Waals forces between atoms. However, she and her colleagues Timothy Sullivan and Peter Niewiarowski were curious about how the lizards cope on surfaces in their natural habitat.

Explaining that previous studies had focused on the reptiles clinging to artificial dry surfaces, Stark says ‘We know they are in tropical environments that probably have a lot of rain and it’s not like the geckos fall out of the trees when it’s wet’. Yet, the animals do seem to have trouble getting a grip on smooth wet surfaces, sliding down wet vertical glass after a several steps even though minute patches of the animal’s adhesive structures do not slip under humid conditions on moist glass. The team decided to find out how Tokay geckos with wet feet cope on wet and dry surfaces, and publish their discovery that geckos struggle to remain attached as their feet get wetter in The Journal of Experimental Biology (“The effect of surface water and wetting on gecko adhesion” [behind a paywall]).

According to the news item, Tokay geclos were used for this study. These are neither small, nor amiable geckos according to the webpage devoted to Tokay Geckos on the anapsid.org website,

Description
Native to SE Asia, these relatively large (12″) geckos are pale gray with bluish spots when they have been in the dark, darkening to dark gray with reddish spots in the light. Like most geckos, tokays are oviparous insectivores.

Young are 2-3″ at hatching. Eggs are laid in rocky crevices or under the eaves of houses. The 2-3 eggs, laid several times a year, are sticky and adhere to surfaces. In captivity, they may be laid on the glass sides of their terraria. Incubation time for the eggs ranges from 2-6 months for the oviparous Gekko species.

Tokays have the specialized lamellae on the pads of their toes which enable them to walk on vertical surfaces, including ceilings. Contrary to popular misconception, these pads are not “sticky” but rather are composed of tiny, microscopic filaments which find equally tiny imperfections in surface – including glass.

Like many lizards, tokays can darken or lighten their ground and spot colors to better blend in with their background.

Personality
Despite the fact that they follow human habitation, finding human dwellings to be great places to find prey, Tokays are the least lovable of the geckos. They are known for their nasty temperament, cheerfully biting the hand that feeds, cleans or otherwise comes into anything resembling close proximity to them. Their bites are powerful–one might say they are the pit bulls of the gecko world…they hang on and let go only when it suits them. Equipped as they are with numerous sharp teeth, the bites can bleed profusely and, even barring subsequent infection, are annoying for days. Note that while I am a strong believer that almost any animal can be habituated to human contact, such contact can be stressful for many species, and geckos as a whole are known for their marked preference to be left alone.

That harness question gets a lot more interesting after you’ve read about the Tokay Geckos, yes? I found the parts about being “the least lovable of the geckos’ and being known for their nasty bites particularly interesting.

Kathryn Knight’s article about the study for the Journal of Experimental Biology (which originated the news item) offers details about the testing on wet surfaces  (but no more about the harnesses),

Next, the trio sprayed the glass plate with a mist of water and retested the lizards, but this time the animals had problems holding tight: the attachment force varied each time they took a step. The droplets were interfering with the lizards’ attachment mechanism, but it wasn’t clear how. And when the team immersed the geckos in a bath of room temperature water with a smooth glass bottom, the animals were completely unable to anchor themselves to the smooth surface. ‘The toes are superhydrophobic [water repellent]’, explains Stark, who could see a silvery bubble of air around their toes, but they were unable to displace the water surrounding their feet to make the tight van der Waals contacts that usually keep the geckos in place.

Then, the team tested the lizard’s adhesive forces on the dry surface when their feet had been soaking for 90 min and found that the lizards could barely hold on, detaching when they were pulled with a force roughly equalling their own weight. ‘That might be the sliding behaviour that we see when the geckos climb vertically up misted glass’, says Stark. So, geckos climbing on wet surfaces with damp feet are constantly on the verge of slipping and Stark adds that when the soggy lizards were faced with the misted and immersed horizontal surfaces, they slipped as soon as the rig started pulling.

Therefore geckos can walk on wet surfaces, so long as their feet are reasonably dry. However, as soon as their feet get wet, they are barely able to hang on and the team is keen to understand how long it takes geckos to recover from a drenching.

Given the number of studies using geckos, I wonder if there are specialists devoted to creating gecko harnesses. In any case, one certainly can appreciate that the practice of science can sometimes be a blood sport. I think the question being asked is intriguing and it’s the first time I’ve seen any study of the gecko’s adhesive qualities being tested on wet surfaces.

Gecko-type robots and Simon Fraser University

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I had to watch the (40 sec.) video a couple times to better marvel at the ‘gecko robot’ that a team of researchers at Simon Fraser University (Vancouver, Canada) have developed.

Here’s a little more information from the Nov. 2, 2011 posting by GrrlScientist on her Punctuated Equilibrium blog at the Guardian science blogs site,

Geckos are amazing animals for so many reasons, but their ability to climb glass windows is especially amazing since their sticky toes are not at all moist, as one would expect. Instead, gecko toes are dry, their adhesive ability the result of van der Waals forces. These are very weak, attractive forces that occur between molecules. For this reason, the gecko’s dry but sticky toe pads have long inspired scientists and engineers, especially mechanical engineers trying to design wall-climbing robots.

It looks like someone has finally succeeded. According to a hot-off-the-presses paper, a group of researchers from Simon Fraser University in British Columbia, Canada, have finally developed a robot – nowhere near as elegant in form as a gecko – that has the gecko’s ability to scale smooth walls and shuffle across ceilings without crashing down onto anyone’s head.

Here are some more details about the technology and the researchers (from the Nov. 1, 2011 SFU media release),

Known as the Tailless Timing Belt Climbing Platform (TBCP-11), the robot can transfer from a flat surface to a wall over both inside and outside corners at speeds of up to 3.4 cm per second. It is fitted with sensors that allow it to detect its surroundings and change direction.

Researchers mimicked the “dry, sticky toe pads” of the gecko by creating an adhesive using a material called polydimethylsiloxane (PDMS), manufactured as tiny mushroom cap-like shapes that are 17 micrometres wide by 10 micrometres high.

Meanwhile, tiny belts drive the robot’s tank-like moves, providing optimum mobility and expandability.

Lead author Jeff Krahn’s work on getting the robot to climb formed the bulk of his master’s thesis. The research was carried out together with engineering science assistant professor Carlo Menon.

This is the smoothest, most efficient climbing robot (stickybot) that I’ve seen. My August 26, 2011 posting featured  stickybots (with video) from  researchers at Stanford University.

Supraparticles, self-assembly, and uniformity and Futurity

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I’m not sure what I find more interesting the research  or the website. First the research, from the August 25, 2011 news item on Futurity,

In another instance of forces behaving in unexpected ways at the nanoscale, scientists [at the University of Michigan] discovered that if you start with small nanoscale building blocks that are varied enough in size, the electrostatic repulsion force and van der Waals attraction force will balance each other and limit the growth of the clusters, enabling formations that are uniform in size. The findings are published in the Nature Nanotechnology.

…

Researchers created the inorganic superclusters—technically called “supraparticles”—out of red, powdery cadmium selenide In many ways the structures are similar to viruses. They share many attributes with the simplest forms of life, including size, shape, core-shell structure, and the abilities to both assemble and dissemble, says co-author Nicholas Kotov.

Here’s a graphic that accompanies the news item,

Under the right circumstances, basic atomic forces can be exploited to enable nanoparticles to assemble into superclusters that are uniform in size and share attributes with viruses. (Credit: T.D.Nguyen)

I’m particularly interested in that comment about the resemblance to viruses. Now on to Futurity, a science news aggregator (from the About Futurity page)

Futurity features the latest discoveries in all fields from scientists at the top universities in the US, UK, and Canada. The site, which is hosted at the University of Rochester, launched in 2009 as a way to share research news with the public.

Who is Futurity?
A consortium of participating universities manages and funds the project. The university partners are members of the Association of American Universities (AAU) and of the Russell Group. Futurity aggregates the very best research news from these top universities.

There are two universities from Canada involved, University of Toronto and McGill University.

Electronic tattoos

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Yes, you can temporarily apply electronics that look like tattoos to your skin. From the August 11, 2011 news item on physorg.com,

Engineers have developed a device platform that combines electronic components for sensing, medical diagnostics, communications and human-machine interfaces, all on an ultrathin skin-like patch that mounts directly onto the skin with the ease, flexibility and comfort of a temporary tattoo.

The team led by professor John Rogers at the University of Illinois has create wearable electronics.

The patches are initially mounted on a thin sheet of water-soluble plastic, then laminated to the skin with water – just like applying a temporary tattoo. Alternately, the electronic components can be applied directly to a temporary tattoo itself, providing concealment for the electronics.

Here’s a video released by the University of Illinois featuring Rogers and his colleague, lead author Dae-Hyeong Kim, describing their work,
http://www.youtube.com/watch?v=tOk7OWZ-Lck

(ETA April 7, 2014: This link leads to a notice that the video is no long available.)

Possible applications for this technology include (from the news item on physorg.com),

In addition to gathering data, skin-mounted electronics could provide the wearers with added capabilities. For example, patients with muscular or neurological disorders, such as ALS, could use them to communicate or to interface with computers. The researchers found that, when applied to the skin of the throat, the sensors could distinguish muscle movement for simple speech. The researchers have even used the electronic patches to control a video game, demonstrating the potential for human-computer interfacing.

The August 11, 2011 news item about this research on Nanwerk features some technical details [Note: The news item on physorg.com also offers technical information but the Nanowerk item from the National Science Foundation offered some additional details.],

The researchers have created a new class of micro-electronics with a technology that they call an epidermal electronic system (EES). They have incorporated miniature sensors, light-emitting diodes, tiny transmitters and receivers, and networks of carefully crafted wire filaments into their initial designs.

The technology is presented—along with initial measurements that researchers captured using the EES—in a paper by lead author Dae-Hyeong Kim of the University of Illinois and colleagues in the August 12, 2011, issue of Science (“Epidermal Electronics “).

…

While existing technologies accurately measure heart rate, brain waves and muscle activity, EES devices offer the opportunity to seamlessly apply sensors that have almost no weight, no external wires and require negligible power.

Because of the small power requirements, the devices can draw power from stray (or transmitted) electromagnetic radiation through the process of induction and can harvest a portion of their energy requirements from miniature solar collectors.

The EES designs yield flat devices that are less than 50-microns thick—thinner than the diameter of a human hair—which are integrated onto the polyester backing familiar from stick-on tattoos.

The devices are so thin that close-contact forces called van der Waals interactions dominate the adhesion at the molecular level, so the electronic tattoos adhere to the skin without any glues and stay in place for hours. The recent study demonstrated device lifetimes of up to 24 hours under ideal conditions.

In light of today’s earlier posting on surveillance, I’m torn between appreciating the technological advance with its attendant possibilities and my concerns over increased monitoring.

Adding to my disconcertment is this comment from one of Rogers’ other colleagues (from the news item on physorg.com),

“The blurring of electronics and biology is really the key point here,” Huang [Northwestern University engineering professor Yonggang Huang] said. “All established forms of electronics are hard, rigid. Biology is soft, elastic. It’s two different worlds. This is a way to truly integrate them.”

Engineers never talk about the social implications of these concepts (integrating biology and electronics) which can be quite frightening and upsetting to some folks depending on how they are introduced to the concept.

While existing technologies accurately measure heart rate, brain waves and muscle activity, EES devices offer the opportunity to seamlessly apply sensors that have almost no weight, no external wires and require negligible power.
Because of the small power requirements, the devices can draw power from stray (or transmitted) electromagnetic radiation through the process of induction and can harvest a portion of their energy requirements from miniature solar collectors.
The EES designs yield flat devices that are less than 50-microns thick—thinner than the diameter of a human hair—which are integrated onto the polyester backing familiar from stick-on tattoos.
The devices are so thin that close-contact forces called van der Waals interactions dominate the adhesion at the molecular level, so the electronic tattoos adhere to the skin without any glues and stay in place for hours. The recent study demonstrated device lifetimes of up to 24 hours under ideal conditions.

Stickybots at Stanford University

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I’ve been intrigued by ‘gecko technology’ or ‘spiderman technology’ since I first started investigating nanotechnology about four years ago.  This is the first time I’ve seen theory put into practice. From the news item on Nanowerk,

Mark Cutkosky, the lead designer of the Stickybot, a professor of mechanical engineering and co-director of the Center for Design Research [Stanford University], has been collaborating with scientists around the nation for the last five years to build climbing robots.

After designing a robot that could conquer rough vertical surfaces such as brick walls and concrete, Cutkosky moved on to smooth surfaces such as glass and metal. He turned to the gecko for ideas.

“Unless you use suction cups, which are kind of slow and inefficient, the other solution out there is to use dry adhesion, which is the technique the gecko uses,” Cutkosky said.

Here’s a video of Stanford’s Stickybot in  action (from the Stanford University News website),

As Cutkosky goes on to explain in the news item,

The interaction between the molecules of gecko toe hair and the wall is a molecular attraction called van der Waals force. A gecko can hang and support its whole weight on one toe by placing it on the glass and then pulling it back. It only sticks when you pull in one direction – their toes are a kind of one-way adhesive, Cutkosky said.

…

“Other adhesives are sort of like walking around with chewing gum on your feet: You have to press it into the surface and then you have to work to pull it off. But with directional adhesion, it’s almost like you can sort of hook and unhook yourself from the surface,” Cutkosky said.

After the breakthrough insight that direction matters, Cutkosky and his team began asking how to build artificial materials for robots that create the same effect. They came up with a rubber-like material with tiny polymer hairs made from a micro-scale mold.

The designers attach a layer of adhesive cut to the shape of Stickybot’s four feet, which are about the size of a child’s hand. As it steadily moves up the wall, the robot peels and sticks its feet to the surface with ease, resembling a mechanical lizard.

The newest versions of the adhesive, developed in 2009, have a two-layer system, similar to the gecko’s lamellae and setae. The “hairs” are even smaller than the ones on the first version – about 20 micrometers wide, which is five times thinner than a human hair. These versions support higher loads and allow Stickybot to climb surfaces such as wood paneling, painted metal and glass.

The material is strong and reusable, and leaves behind no residue or damage. Robots that scale vertical walls could be useful for accessing dangerous or hard to reach places.

The research team’s paper, Effect of fibril shape on adhesive properties, was published online Aug. 2, 2010 in Applied Physics Letter.

Nano activities for the summer months

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Courtesy of the July 2010 NISE (Nanoscale Informal Science Education) Net (work) newsletter, I have a list of nano-related activities taking place in various science museums and centres in the US. From the newsletter,

  • The Sciencenter in Ithaca, NY is integrating two mornings of nano programming into every two-week camp session. Sciencenter camp activities are designed for girls and boys entering grades 2 – 6 in the fall of 2010. Sciencenter educators plan an assortment of active, physical games, focused classroom experiences, special presentations, and free exploration of the museum and the science park. More information can be found at http://www.sciencenter.org/programs/sciencentersummercamp.asp
  • The Children’s Museum of Science and Technology (CMOST) in Troy, NY is partnering with the College of Nanoscale Science and Engineering to offer two week long sessions of Nano Camp! One week will be all inclusive, and the second week is a ladies-only GIST (Girls in Science and Technology) program. More information can be found at http://www.cmost.org/programs/summer_gist.php
  • The Arts and Science Center in Pine Bluff, AR held a weeklong nano camp in early June using some of the NanoDays kit activities.
  • The Museum of Science in Boston, MA is hosting its fourth round of science communication workshops for NSF-funded REU (Research Experience for Undergraduate) students from Boston-area nano research centers, and is working with the Discovery Center Museum and the UW Madison NSEC and MRSEC to adapt this set of workshops for integration into their REU programs. The goal of these workshops is to help to cultivate a new generation of nano and materials science researchers aware of the broader context of their research and equipped with the skills to communicate effectively on interdisciplinary research teams and to engage broader audiences.[emphases mine]
  • In about a month, the National Nanotechnology Infrastructure Network (NNIN) REU will gather at the University of Minnesota for their network-wide convocation.  All 80 NNIN REU interns will present a talk and a poster.  Plus, all 18 International REUs, the iREUs, will be attending having just gotten home from Belgium, Germany or Japan!  Finally, staff from every site, along with many of the interns’ parents and friends, attend.  It’s an exciting event where staff and interns meet and find out what everyone has been up to over the summer. The presentations are web-cast and details and schedules can be found at http://www.nano.umn.edu/nninreuconvocation2010/.
  • The Summer Institute for Physics Teachers is currently going on at Cornell’s Center for Nanoscale Systems. The course, open to high school physics teachers, includes lectures are given by Dr. Julie Nucci and many Cornell faculty on topics such as electronics, photonics, nanotechnology, and particle physics. Lab tours provide a glimpse into state-of-the-art academic research.  The lab activities, which are co-developed by high school physics teachers and Cornell scientists, are presented by teachers.

I highlighted the science communication workshops for the US undergraduates in light of a recent (July 8, 2010) University of British Columbia media release announcing two recent federal grants including this one,

young researchers at UBC were awarded a further $1.6 million from the Collaborative Research and Training Experience (CREATE) program to help upgrade their skills for a successful transition to the workplace.

…

The CREATE grant to UBC is part of a $32-million investment over six years from NSERC, for 20 projects at Canadian universities. The funding will give science and engineering graduates an opportunity to expand their professional and personal skills to prepare them for the workplace.

While the two programmes are markedly different, the fact of their existence is intriguing. I don’t believe communication skills workshops or programmes to upgrade workplace skills for budding young scientists have been a feature of science training (in Canada anyway) until fairly recently. If you know differently, please do comment.

I’ve long been interested in the work being done on adhesive forces (usually Spiderman or geckos are featured in the headline for the news release) so I was quite happy to see this in the newsletter,

→ Geckos!

Check out our new program Biomimicry: Synthetic Gecko Tape through Nanomolding.  The hands-on activity gives visitors a glimpse of one of the methods used by researchers to make synthetic gecko tape.  Visitors make their own synthetic gecko tape with micron-sized hairs that mimic the behavior of the gecko foot and test how much weight their gecko tape can hold using LEGOs. The activity was designed to fit into a classroom/camp program, but can be adapted for a museum floor.

If the scientists are successful, it means you won’t need glue to stick things together, for example, putting up curtain rods. (Some curtain rods use adhesive pads so you can pull them on and off the walls but if you do that too many times you lose the adhesive properties; Spiderman and geckos don’t experience that problem.)

I found the document which tells you exactly how to create your synthetic gecko tape. You may not have the materials needed easily available but if you’re interested, the instructions are here.

This month’s nano haiku,

Surface to Volume
new science with a nano
Golden Ratio

by Luke Doney of the Museum of Nature and Science in Dallas, TX

If you want to check NISE Net, go here.