Tag Archives: nanoscale

Ultra-thin gold sheet.

Scientists create the thinnest gold plates ever, just two atoms thick

Researchers at the University of Leeds have created the thinnest unsupported gold plate ever — just two atoms thick.

Ultra-thin gold sheet.

The nanoscale gold sheet. Image has been artificially colored.
Image credits University of Leeds.

The team reports that the thickness of their gold plate is just 0.47 nanometres, making it one million times thinner than a human fingernail. For comparison, the thickness of a human strand of hair ranges between 17 to 181 nanometres. The researchers call the plate ‘2-D’ gold because it’s just two-atoms thick.

Nanometals

“This work amounts to a landmark achievement,” says lead author Dr. Sunjie Ye, from Leeds’ Molecular and Nanoscale Physics Group and the Leeds Institute of Medical Research.

“Not only does it open up the possibility that gold can be used more efficiently in existing technologies, it is providing a route which would allow material scientists to develop other 2-D metals. This method could innovate nanomaterial manufacturing.”

As the plate is built from only two layers of atoms, all of them are surface atoms, i.e. none of them are completely covered by others. This is especially important for catalysts, whose efficiency varies with the amount of surface area they can present to the environment.

Gold zoom.

Electron microscope image showing the arrangement of gold atoms on the nanosheet.
Image credits University of Leeds.

Laboratory tests show that the 2-D gold plate is 10 times more efficient as a catalytic substrate than the currently used gold nanoparticles. These gold nanoparticles are 3-D materials and the majority of their atoms reside in their bulk rather than on the surface, so they are inactive.

In addition to pointing the way towards new, better catalysts for a range of industrial processes, the material could also have applications in the medical device and electronics industries. The team writes that it can also form the basis of artificial enzymes that could be applied in rapid, point-of-care medical diagnostic tests and in water purification systems.

The team’s synthesis process takes place in a watered-down solution of chloroauric acid, an inorganic substance that contains gold. This substance is then reduced to produce metallic gold using a ‘confinement agent,’ a chemical that encourages the gold to form as a very thin sheet.

Because at this point the gold particles are still in the nanoscale, it appears green in the water. Also due to the resulting shapes, the team describes it as ‘gold nanoseaweed’.

Gold sheets.

Image credits University of Leeds.

Professor Stephen Evans, head of the Leeds’ Molecular and Nanoscale Research Group and lead researcher on the project, says that the findings could help several industries cut down on production costs due to the high surface-to-volume ratios of the 2-D gold sheets.

“Gold is a highly effective catalyst. Because the nanosheets are so thin, just about every gold atom plays a part in the catalysis. It means the process is highly efficient,” says Professor Evans.

“Our data suggests that industry could get the same effect from using a smaller amount of gold, and this has economic advantages when you are talking about a precious metal.”

Furthermore, the sheets are also flexible despite their extreme thinness. This makes them ideal for a variety of applications in electronics, especially in the building of components, bendable screens, electronic inks, or transparent conducting displays.

Professor Evans says there are many similarities between the 2-D gold and graphene, the first 2-d material ever created in the lab. However, he also cautions that the transition from new materials to working products takes a long time, and that “you can’t force it to do everything you might like to”.

“With graphene, people have thought that it could be good for electronics or for transparent coatings — or as carbon nanotubes that could make an elevator to take us into space because of its super strength,” he explains. “I think with 2-D gold we have got some very definite ideas about where it could be used, particularly in catalytic reactions and enzymatic reactions.”

“We know it will be more effective than existing technologies, so we have something that we believe people will be interested in developing with us.”

The paper “Sub‐Nanometer Thick Gold Nanosheets as Highly Efficient Catalysts” has been published in the journal Advanced Science.

Meet the world’s smallest snowman

He’s under 3 micrometers tall and was carved with an electron microscope.

Image credits: Credit: Todd Simpson, Western University Nanofabrication Facility, Ontario, Canada.

It’s always nice when you see a snowman in wintertime, but you won’t see one on the side of the road — unless you happen to have an electron microscope on you.

It all started in 2005, when Todd Simpson from Western University was working on creating isolated silica spheres. He used a relatively common technique in the field, taking a polymer layer with tiny holes and depositing a silica solution inside these holes. When the film is removed, round silica spheres are left behind.

However, in some cases, the silica fell through the hole, creating what is called a “dimer” — a group of two monomers joined by chemical bonds. In a few rare cases, the dimer fell on a pre-formed silica sphere, forming a three-sphere stack. That’s when Simpson realized he had all the makings of a snowman.

Image credits: Western University Nanofabrication Facility, Ontario, Canada and Dr. Todd Simpson

Of course, it didn’t have any face or arms so Simpson got to work. He took out an old sample and used the lab’s focused ion beam instrument to carve out eyes and mouth in the top sphere. He used the same instrument to deposit platinum arms to complete his work. In total, each sphere has a diameter of about 0.9 micrometers (μm) in diameter which means that in total, the snowman is just under 3 μm tall. Just so you can get an idea of how small that is, a micrometer is 1,000 times smaller than a millimeter. The diameter of human hair ranges from about 10 to 200 µm.

This isn’t the first extra-small snowman ever created. In 2009, David Cox, a National Physical Laboratory research fellow at the University of Surrey, UK, created another nanoscale snowman using a similar technology — though that one is much taller, at 30μm. They’re both adorable and they both go to show how much our technology has progressed lately.

The Ohio University's nano-sized monster truck which participated in the first ever NanoRace hosted in France. Credit: Ohio University.

Tiniest ‘monster trucks’ race over a fraction of a width of the human hair in the first NanoRace

On a nanoscale luxurious track made of gold and silver, molecular machines competed in the world’s shortest race by distance. But although the track was a fraction of the width of a human hair, our molecular vehicles were even smaller which explains why the whole race took no fewer than 30 hours to designate the winner.

The Ohio University's nano-sized monster truck which participated in the first ever NanoRace hosted in France. Credit: Ohio University.

The Ohio University’s nano-sized monster truck which participated in the first ever NanoRace hosted in France. Credit: Ohio University.

Not your typical drag race

The so-called “nanorace” took place in April at the CNRS’s Centre d’élaboration de matériaux et d’études structurales (CEMES) in Toulouse. This research facility houses a one of a kind scanning tunneling microscope (STM), which is equivalent to four STMs and without which such a race wouldn’t have been possible. An STM is a revolutionary instrument that uses a tip to measure the electric conductance between it and a material’s surface. This screening provides an electronic map of the surface down to the molecular or atomic level. Ultimately, the French STM could image tiny ‘vehicles’ made out of molecules at a resolution of  2 picometers, or 10-12 meters.

In this case, because the objects involved were extremely tiny, the STM instrument served a double role: measuring and propulsion. Each car had to be equipped with positive charge receptors while the microscope’s tip also supplied the energy to move the cars forward.

STM images of the Nanocars. Credit: CNRS.

STM images of the Nanocars. Credit: CNRS.

[panel style=”panel-warning” title=”The rules of the NanoRace at a glance” footer=””]

  • The track is 20nm+1 turn+50nm+1 turn+20nm
  • Maximum 38 hours of racing
  • One section of the gold surface per team
  • Maximum 6h to clean the track before the race starts
  • No tip changes for 38 hours
  • Pushing the NanoCar is not allowed
  • Authorization to change the NanoCar

[/panel]

A tiny monster truck

One of the teams involved in the race came from Ohio University. Their molecular contraption only measures 3.5 nanometers in length, made out of a chassis of H-shaped pseudorotaxane with four relatively large cucurbituril molecules serving as the wheels, as captioned in this article’s first image. Ironically, when it was completed, the molecular vehicle looked like a monster truck. Its official name is the Bobcat Nanowagon, though.

“The overarching goal was to advertise nanoscience to the public,” Eric Masson, one of the co-leaders of the Ohio University team said in a statement. “Then there was the technical challenge of manipulating multiple nanocars at the same time using a scanning tunneling microscope, or STM, instrument. Additionally, every team had its own goal. Ours was to see if we could deposit an intact supramolecular assembly onto a surface, and control its motion.”

In all, six teams from three continents entered the race meant to promote nanoscience to the general public. The Bobcat Nanowagon never left the team’s lab in Ohio, though, since the Toulouse facility only had four tips that could each control only one nanocar. Instead, the Ohio scientists left their nanowagon back home in the lab, but controlled it remotely from CNRS. “We manipulated the car at the atomic scale from half a globe away,” Saw-Wai Hla, who also co-led the Bobcat Nanowagon team.

In the end, the Bobcat Nanowagon didn’t get to finish the race getting stuck 43 nanometers down the gold track after a Midwest power blip forced the molecules onto a rough section. It still traveled farther than three other contestants earning it third place in the first ever nanorace. First place went to the Nanoprix team, a US-Austrian collaboration (Rice/Graz), whose car traveled 1 micron at a snail’s pace of 29 hours. Second place went to a Swiss team from Basel which completed 133 nm of track in 6-and-a-half hours.

Credit: Nanorace, ZME Science.

Credit: Nanorace, ZME Science.

Besides promoting nanoscience to the public (and being extremely cool), such competitions could also provide new discoveries and insights. When Masson and Hla made their nanowagon, they had to make various iterations of the chassis molecules suspended in water. About 70 percent of the resulting structures looked like two-wheeled hover boards, a few had three wheels, and about 10 percent had all four wheels.

“That means that it was easier to break the chassis, a covalent bond, than to break the noncovalent bonds between the chassis and the wheels,” Masson said, who recently presented his team’s findings at the 254th National Meeting & Exposition of the American Chemical Society (ACS). “That’s completely counterintuitive because typically a noncovalent bond is much weaker than a covalent bond. It’s a theoretical curiosity.”

So there might be quite a few discoveries waiting to happen. At the end of the day, though, it’s all about the race itself, not the finish line.

“Our excitement is really about the fundamental science,” Hla says. “This is just the beginning.”

Image: DARPA

From atoms to life size: manufacturing from nanoscale up to macro

Image: DARPA

Image: DARPA

DARPA just announced the launch of a new extremely exciting program: Atoms to Product (A2P). The aim is to develop a suit of technologies that will allow manufacturing of products from the nanoscale up to what we know as ‘life size’. The revolutionary miniaturization and assembly methods would work at scales 100,000 times smaller than current state-of-the-art technology. If found successful, then DARPA might be able to make macroscale products (anything from the size of a tennis ball to a tank) that exhibit nanoscale or quantum properties usually encountered  when we delve in the core of atoms. 

When fabricated at extremely small scales (a few ten-billionths of a meter), materials exhibit extremely peculiar behavior which in some cases can be useful to society. These include quantized electrical characteristics, glueless adhesion, rapid temperature changes, and tunable light absorption and scattering that, if available in human-scale products and systems, could offer potentially revolutionary defense and commercial capabilities.

“If successful, A2P could help enable creation of entirely new classes of materials that exhibit nanoscale properties at all scales,” DARPA program manager John Main said in a news release, “It could lead to the ability to miniaturize materials, processes and devices that can’t be miniaturized with current technology, as well as build three-dimensional products and systems at much smaller sizes.”

This kind of scaled assembly, working from the nanoscale up to millions of orders of magnitude in size, is widely found in nature. Prime examples include all plants and animals, which are effectively systems assembled from atomic- and molecular-scale components a million to a billion times smaller than the whole organism. What DARPA is trying to do is to lay a foundation for a similar assembly method that might lead to a whole new class of materials.

So, how excited should we be about this? Not all DARPA projects work and the defense agency is known for dabbling in a slew of domains. When its projects work, however, they offer the opportunity to transform the world. Though a defense institution, DARPA has slipped many of its tech to civilian hands. To name a few: internet, GPS or graphical user interface.

Watching Nanoscale Fluids Flow

Nanoscale nanofluids flowing.

Nanofluids, fluids containing nanometer-sized particles, show immense potential for future engineering. Even water flowing through nanotubes flows much faster than traditional mechanics says it should be possible. Now, researchers have found a way to directly image nanofluids.

Researchers at Caltech have applied a new imaging technique called four-dimensional (4D) electron microscopy to the nanofluid dynamics problem. The technique was invented at Caltech, and basically involves a stream of ultra-fast-moving electrons bombarding a sample in a carefully timed manner. Each electron scatters off a sample, providing a still image that lasts about a millionth of a billionth of a second. They are able to make millions and millions of these scatters, and stitch together the images – creating the result you see below.

Ahmed Zewail, the Linus Pauling Professor of Chemistry and professor of physics, and Ulrich Lorenz, a postdoctoral scholar in chemistry, the authors of the paper, used single laser pulses to melt the lead cores of individual zinc oxide nanotubes. Then, they observed how the hot pressurized liquid moved within the tubes.

“These observations are particularly significant because visualizing the behavior of fluids at the nanoscale is essential to our understanding of how materials and biological channels effectively transport liquids,” says Zewail. In 1999, Zewail won the Nobel Prize for his development of femtosecond chemistry.

Scientific Reference: Lorenz, Ulrich J. and Zewail, Ahmed H. (2014) Observing liquid flow in nanotubes by 4D electron microscopy. Science, 344 (6191). pp. 1496-1500. ISSN 0036-8075.

Creating the smallest Mona Lisa – just 30 microns across

Mona Lisa is probably the most well known picture in the world – it’s been painted thousands of times, inspired countless artists, and her enigmatic smile still puzzles researchers and artists alike; but never before has it been painted on such a small canvas.

Picture source

Picture source

Demonstrating a very potent nanotechnique, researchers have made a miniature Mona Lisa that stretches 30 microns across – about a third of the width of a human hair. The team from Georgia Tech created the molecular masterpiece using an atomic force microscope and a process which they have called ThermoChemical NanoLithography, or TCNL for short.

Thermochemical nanolithography (TCNL) employs heated nano-size tips to create heat which activates chemical reactions to change the functionality of a nanoscale surface  or obtain new nanostructures. It’s not a novel technique, being used for the first time in 2007, also at Georgia Tech.

The pixels of the “Mini Lisa” each measure 125-nanometer , and they are basically a confined set of chemical reactions. By controlling the amount of heat which goes into the molecules, researchers influenced the shade of grey of every ‘pixel’ – making this extremely small work of art a brilliant demonstration of TCNL’s ability to make variations in molecular concentrations on this extremely small scale. This has the potential to be applied in nanoscale manufacturing.

“We envision TCNL will be capable of patterning gradients of other physical or chemical properties, such as conductivity of graphene,” study researcher Jennifer Curtis said in a statement. “This technique should enable a wide range of previously inaccessible experiments and applications in fields as diverse as nanoelectronics, optoelectronics and bioengineering.”

This is not the first time the Mona Lisa has been used in science – earlier this year, NASA beamed the famous image to the Moon, using a very powerful laser.

The findings were detailed in the Journal Langmuir.

Graphene allows nano-engineering control for the first time

The amazing properties of graphene are being put to use more and more, as Evan Reed and Mitchell Ong from the Stanford School of Engineering have described a new way of engineering piezoelectrics into graphene. The study was published in the ACS Nano Journal.

When you apply a mechanical stress to certain materials, such as crystals, ceramics, or even biological materials, they become electrically charged, and this property is called piezoelectricity – basically, it is electricity resulting from pressure. Using this effect, their work extends engineering control to the nanoscale for the first time. Reed explained that the proportions of the applied pressure directly varies with the electrical field, and this approach might be the key to manipulating electronics at the nanoscale, and this phenomenon can bring a revolution in the field of straintronics. This is where graphene steps in.

Graphene, which is basically a one-atom thick layer of carbon may offer an unprecedented degree of control over optical, electrical and mechanical properties for applications such as nanoscale transistors and touchscreens. In order to measure the piezoelectric field of graphene, they simulated graphene doped with fluorine, potassium, hydrogen, lithium and combinations of fluorine and lithium and fluorine and hydrogen on either sides. Researchers were absolutely surprised with the results, reporting that the effect of the 2D graphene were practically similar to those of 3D materials.

Based on these positive results, scientists hope they can continue their studies, which can have a number of applications in a number of fields, including electronics, chemical sensing, energy harvesting, photonics and many, many more.

Via AZonano

“No small matter: Science on the nanoscale” review

nanoscale

Nanotechnology is perhaps the field with the most spectacular development over the past years, but it can be really hard to understand what’s going on at that scale, mostly because we can’t see it (doh!), but also because the laws that apply there are slightly different.

No small matter:  Science on the nanoscale is the work of George M. Whitesides, the man with the highest H index of all living chemists and Felice C. Frankel, winner of the Photographic Society of America’s 2009 Progress Medal, and it has to be said, it’s awesome. Before I get into talking more about the book, I want to say that this is not a paid review, and everything I write is my honest opinion.

The book is written mostly for those who are just getting into nanotechnology or have a basic grasp of what’s going on there, but everybody has something to take from it, regardless of their interests and current knowledge; it probably fits best with undergrads, though. But, if you wanted to know what happens at a molecular level when you play the violin, take a pregnancy test or lit a candle (and way more), this is what you need to read.

A small revolution is remaking the world. The only problem is, we can’t see it. This is the book’s catchphrase, but it’s a bit too simple if you ask me. The virtual voyage the authors have prepared for the readers is just breathtaking, filled with detailed pictures of seemingly invisible objects, such as nanotubes, viruses, etc., proving what photography and high power microscopes can do when working together.

Basically it provides an overview of where nanotechnology is now, looking at what it has been and what it will probably be, as well as the advantages and dangers that this microscopic (or submicroscopic) world brings. In layman’s terms, you can call it an introduction in the science of the little; and what an introduction it is! What really convinced me of the value of the book is that aside from it’s educational part (which is explained logically, in detail, but kept simple) was it’s interesting part. I often found myself reading one page after another and forgetting to look at the pictures, even though they were really great. This happened because the information is presented in a clear, explosive and informal manner, allowing readers to grasp the basic core of nanotechnology.

“The textbook is well-written and concise, allowing readers with little or no prior knowledge about nanotechnology and nanoscience to understand and appreciate the concepts easily.”
Tan Lay Theng
Republic Polytechnic, Singapore

The simplicity is definitely something worth admiring, because an area as complex as nanotech involves many fields (physics, chemistry, quantum mechanics, etc) and binds them together. All in all, this is definitely something worth reading, whether you’re a science enthusiast or not, regardless of your age.

Get it via Amazon