Tag Archives: Technical University of Denmark (DTU)

World’s smallest record features Christmas classic “Rockin’ Around the Christmas Tree”

Scientists like to have a little fun too as this December 23, 2022 news item on Nanowerk shows,

Measuring only 40 micrometres in diameter, researchers at DTU Physics have made the smallest record ever cut. Featuring the first 25 seconds of the Christmas classic “Rocking Around the Christmas Tree” [sic], the single is cut using a new nano-sculpting machine – the Nanofrazor – recently acquired from Heidelberg Instruments. The Nanofrazor can engrave 3D patterns into surfaces with nanoscale resolution, allowing the researchers to create new nanostructures that may pave the way for novel technologies in fields such as quantum devices, magnetic sensors and electron optics.

”I have done lithography for 30 years, and although we’ve had this machine for a while, it still feels like science fiction. We’ve done many experiments, like making a copy of the Mona Lisa in a 12 by 16-micrometre area with a pixel size of ten nanometers. We’ve also printed an image of DTU’s founder – Hans Christian Ørsted – in an 8 by 12-micrometre size with a pixel size of 2.540.000 DPI. To get an idea of the scale we are working at, we could write our signatures on a red blood cell with this thing,” says Professor Peter Bøggild from DTU Physics.

“The most radical thing is that we can create free-form 3D landscapes at that crazy resolution – this grey-scale nanolithography is a true game-changer for our research”.

The scientists show how they inscribed the song onto the world’s smallest record (Note 1: You will not hear the song. Note 2: i don’t know how many times I’ve seen news releases about audio files (a recorded song, fish singing, etc.) that are not included … sigh),

A December 22, 2022 Technical University of Denmark press release (also on EurekAlert), which originated the news item, provides detail about the work,

Nanoscale Christmas record – in stereo
The Nanofrazor is not like a printer adding material to a medium; instead, it works like a CNC (computer numerical controle) machine removing material at precise locations, leaving the desired shape behind. In the case of the miniature pictures of Mona Lisa and H.C. Ørsted, the final image is defined by the line-by-line removal of polymer until a perfect grey-scale image emerges. To Peter Bøggild, an amateur musician and vinyl record enthusiast, the idea of cutting a nanoscale record was obvious.

“We decided that we might as well try and print a record. We’ve taken a snippet of Rocking Around The Christmas Tree and have cut it just like you would cut a normal record—although, since we’re working on the nanoscale, this one isn’t playable on your average turntable. The Nanofrazor was put to work as a record-cutting lathe – converting an audio signal into a spiralled groove on the surface of the medium. In this case, the medium is a different polymer than vinyl. We even encoded the music in stereo – the lateral wriggles is the left channel, whereas the depth modulation contains the right channel. It may be too impractical and expensive to become a hit record. To read the groove, you need a rather costly atomic force microscope or the Nanofrazor, but it is definitely doable.”

High-speed, low-cost nanostructures

The NOVO Foundation grant BIOMAG, which made the Nanofrazor dream possible, is not about cutting Christmas records or printing images of famous people. Peter Bøggild and his colleagues, Tim Booth and Nolan Lassaline, have other plans. They expect that the Nanofrazor will allow them to sculpt 3D nanostructures in extremely precise detail and do so at high speed and low cost – something that is impossible with existing tools.

“We work with 2D materials, and when these ultrathin materials are carefully laid down on the 3D landscapes, they follow the contours of the surface. In short, they curve, and that is a powerful and entirely new way of “programming” materials to do things that no one would believe were possible just fifteen years ago. For instance, when curved in just the right way, graphene behaves as if there is a giant magnetic field when there is, in fact, none. And we can curve it just the right way with the Nanofrazor,” says Peter Bøggild.

Associate professor Tim Booth adds:

“The fact that we can now accurately shape the surfaces with nanoscale precision at pretty much the speed of imagination is a game changer for us. We have many ideas for what to do next and believe that this machine will significantly speed up the prototyping of new structures. Our main goal is to develop novel magnetic sensors for detecting currents in the living brain within the BIOMAG project. Still, we also look forward to creating precisely sculpted potential landscapes with which we can better control electron waves. There is much work to do.”

Postdoc Nolan Lassaline (who cut the Christmas record), was recently awarded a DKK 2 Mio. VILLUM EXPERIMENT grant to create “quantum soap bubbles” in graphene. He will use the grant – and the Nanofrazor – to explore new ways of structuring nanomaterials and develop novel ways of manipulating electrons in atomically thin materials.

“Quantum soap bubbles are smooth electronic potentials where we add artificially tailored disorders. By doing so, we can manipulate how electrons flow in graphene. We hope to understand how electrons move in engineered disordered potentials and explore if this could become a new platform for advanced neural networks and quantum information processing.”

The Nanofrazor system is now part of the DTU Physics NANOMADE’s unique fabrication facility for air-sensitive 2D materials and devices and part of E-MAT, a greater ecosystem for air-sensitive nanomaterials processing and fabrication led by Prof. Nini Pryds, DTU Energy.

While it’s not an audio file from the smallest record, this features Brenda Lee (who first recorded the song in 1958) in a ‘singalong’ version of “Rockin’ Around the Christmas Tree,”

Bøggild was last featured here in a December 24, 2021 posting “Season’s Greetings with the world’s thinnest Christmas tree.”

Have a lovely Christmas/Winter Solstice/Kwanzaa/Hannukah/Saturnalia/??? celebration!

Season’s Greetings with the world’s thinnest Christmas tree

Courtesy: Technical University of Denmark

I haven’t seen one of these in a while. It used to be a relatively common occurrence (especially during a holiday) that scientists would create the world’s smallest XXX and send a press release. I’ve missed them so I’m glad to see this one pop up.

A December 23, 2021 news item on phys.org announces the world’s thinnest Christmas tree,

A Christmas tree with a thickness of one atom has been made at DTU [Technical University of Denmark]. It shows how terahertz measurements can be used to ensure the quality of graphene.

A December 22, 2021 DTU press release by by Tore Vind Jensen, which originated the news item, provides more technical detail,

The Christmas tree in the pictures above is 14 centimeters long. Since it is made of graphene, it consists of carbon atoms in only one layer and is only a third of a nanometer thick. It is cut out of a 10-meter long roll of graphene, transferred in one piece using a rebuilt laminating machine and then scanned with terahertz radiation.

The experiment shows that continuous quality control can be done during the production of graphene, which is expected to play a significant role in future high-speed electronics, i.e. medical instruments and sensors.

Graphene is a so-called two-dimensional material, i.e. it consists of atoms in one cohesive layer that is only one atom thin. It is more robust, stiffer and better at conducting electricity and heat than any other material we know of. Therefore, graphene is an obvious candidate for electronic circuits that take up less space, weigh less, are bendable and are more efficient than the electronics we know today.

“Even if you could make a pencil drawing of a Christmas tree and lift it off the paper—which, figuratively, is what we have done—it would be much thicker than one atom. A bacterium is, e.g. 3000 times thicker than the graphene layer we used. That’s why I dare call this the world’s thinnest Christmas tree. And although the starting point is carbon, just like the graphite in a pencil, graphene is at the same time even more conductive than copper. The “drawing” is made in one perfect layer in one piece, ” says Professor Peter Bøggild who lead the team behind the Christmas tree experiment.

“But behind the Christmas joke hides an important breakthrough. For the first time, we managed to make an in-line quality control of the graphene layer while we transferred it. Doing this is the key to gaining stable, reproducible and usable material properties, which is the prerequisite for utilizing graphene in, e.g. electronic circuits.”

30,000 times thinner than kitchen film

As the researchers have done in this case, the graphene can be “grown” on copper film. The graphene is deposited on a roll of copper foil at around 1000 ° C. That process is well known and well-functioning. But a lot can go wrong when the ultra-thin graphene film is moved from the copper roller to where it is used. Since graphene is 30,000 times thinner than kitchen film, it is a demanding process. Researcher Abhay Shivayogimath has been behind several new inventions in DTU’s transfer process, ensuring a stable transfer of the graphene layers from the copper roll.

Moreover, there has been no technology that could control the electrical quality of graphene on the go—while transferring it. This year Peter Bøggild and his colleague Professor Peter Uhd Jepsen from DTU Fotonik, one of the world’s leading terahertz researchers, established a way to do it.

The colored images are measurements of how the graphene layer absorbs terahertz radiation. The absorption is directly related to the electric conductivity: the better the conductive graphene, the better it absorbs.

Terahertz rays are high-frequency radio waves that lie between infrared radiation and microwaves. Like X-rays, they can be used to scan human bodies, as we know it from airport security. Terahertz rays can also take pictures of the electrical resistance of the graphene layer. By connecting the terahertz scanner to the machine that transfers the graphene film, it is possible to image the electrical properties of the film during the transfer process.

Official international measurement standard

Suppose the implementation of graphene and other 2D materials is to be accelerated. In that case, ongoing quality assurance is a prerequisite, says Peter Bøggild. Quality control precedes trust, he says. The technology can guarantee that graphene-based technologies are manufactured more uniformly and predictably with fewer errors. This year, the DTU researchers’ method was approved as the first official international measurement standard for graphene. Their method was described earlier this year in the article ‘Terahertz imaging of graphene paves the way to industrialisation.’

The potential is excellent. Graphene and other two-dimensional materials can e.g. enable the manufacturing of high-speed electronics performing lightning-fast calculations with far less power consumption than the technologies we use today. But before graphene can become more widespread on an industrial scale and be used in electronics, we encounter in everyday life three main problems must be solved.

First, the price is too high. More and faster production is needed to bring the price down. But with that, you face the second problem: When you increase the speed and can not at the same time check the quality, the risk of error also increases dramatically. At high high-speed transfer, everything must be set precisely.This brings us to the third problem: How do you know what is precise?

It requires measurements. And preferably measurements during the actual transfer process. The DTU team is convinced that the best bet on that method is quality control using terahertz radiation.

Peter Bøggild emphasizes that these three problems have not been solved with the new method alone: “We have taken a very significant step. We have converted a laminating machine into a so-called roll-2-roll transfer system. It gently lifts the graphene layer from the copper roll on which the graphene layer is grown and moves it onto plastic foil without it breaking, becoming wrinkled or dirty. When we combine this with the terahertz system, we can immediately see if the process has gone well. That is, whether we have unbroken graphene with low electrical resistance,” says Peter Bøggild.

Joyeux Noël et une bonne année 2022!

Fake graphene

Michael Berger’s October 9, 2018 Nanowerk Spotlight article about graphene brings to light a problem, which in hindsight seems obvious, fake graphene (Note: Links have been removed),

Peter Bøggild over at DTU [Technical University of Denmark] just published an interesting opinion piece in Nature titled “The war on fake graphene”.

The piece refers to a paper published in Advanced Materials (“The Worldwide Graphene Flake Production”) that studied graphene purchased from 60 producers around the world.

The study’s [“The Worldwide Graphene Flake Production”] findings show unequivocally “that the quality of the graphene produced in the world today is rather poor, not optimal for most applications, and most companies are producing graphite microplatelets. This is possibly the main reason for the slow development of graphene applications, which usually require a customized solution in terms of graphene properties.”

A conclusion that sounds even more damming is that “our extensive studies of graphene production worldwide indicate that there is almost no high quality graphene, as defined by ISO [International Organization for Standardization], in the market yet.”

The team also points out that a large number of the samples on the market labelled as graphene are actually graphene oxide and reduced graphene oxide. Furthermore, carbon content analysis shows that in many cases there is substantial contamination of the samples and a large number of companies produce material a with low carbon content. Contamination has many possible sources but most likely, it arises from the chemicals used in the processes.

Peter Bøggild’s October 8, 2018 opinion piece in Nature

Graphite is composed of layers of carbon atoms just a single atom in thickness, known as graphene sheets, to which it owes many of its remarkable properties. When the thickness of graphite flakes is reduced to just a few graphene layers, some of the material’s technologically most important characteristics are greatly enhanced — such as the total surface area per gram, and the mechanical flexibility of the individual flakes. In other words, graphene is more than just thin graphite. Unfortunately, it seems that many graphene producers either do not know or do not care about this. …

Imagine a world in which antibiotics could be sold by anybody, and were not subject to quality standards and regulations. Many people would be afraid to use them because of the potential side effects, or because they had no faith that they would work, with potentially fatal consequences. For emerging nanomaterials such as graphene, a lack of standards is creating a situation that, although not deadly, is similarly unacceptable.

It seems that the high-profile scientific discoveries, technical breakthroughs and heavy investment in graphene have created a Wild West for business opportunists: the study shows that some producers are labelling black powders that mostly contain cheap graphite as graphene, and selling them for top dollar. The problem is exacerbated because the entry barrier to becoming a graphene provider is exceptionally low — anyone can buy bulk graphite, grind it to powder and make a website to sell it on.

Nevertheless, the work [“The Worldwide Graphene Flake Production”] is a timely and ambitious example of the rigorous mindset needed to make rapid progress, not just in graphene research, but in work on any nanomaterial entering the market. To put it bluntly, there can be no quality without quality control.

Here are links to and citations for the study providing the basis for both Berger’s Spotlight article and Bøggild’s opinion piece,

The Worldwide Graphene Flake Production by Alan P. Kauling, Andressa T. Seefeldt, Diego P. Pisoni, Roshini C. Pradeep, Ricardo Bentini, Ricardo V. B. Oliveira, Konstantin S. Novoselov [emphasis mine], Antonio H. Castro Neto. Advanced Materials Volume 30, Issue 44 November 2, 2018 1803784 https://doi.org/10.1002/adma.201803784

The study which includes Konstantin Novoselov, a Nobel prize winner for his and Andre Geim’s work at the University of Manchester where they first isolated graphene, is behind a paywall.