Category Archives: graphene

3D-printed graphene sensors for highly sensitive food freshness detection

I love the opening line (lede). From a June 29, 2020 news item on Nanowerk,

Researchers dipped their new, printed sensors into tuna broth and watched the readings.

It turned out the sensors – printed with high-resolution aerosol jet printers on a flexible polymer film and tuned to test for histamine, an allergen and indicator of spoiled fish and meat – can detect histamine down to 3.41 parts per million.

The U.S. Food and Drug Administration has set histamine guidelines of 50 parts per million in fish, making the sensors more than sensitive enough to track food freshness and safety.

I find using 3D-printing techniques to produce graphene, a 2-d material, intriguing. Apparently, the technique is cheaper and offers an advantage as it allows for greater precision than other techniques (inkjet printing, chemical vapour depostion [CVD], etc.)

Here’s more detail from a June 25, 2020 Iowa State University news release (also on EurekAlert but published June 29, 2020), which originated the news item,

Making the sensor technology possible is graphene, a supermaterial that’s a carbon honeycomb just an atom thick and known for its strength, electrical conductivity, flexibility and biocompatibility. Making graphene practical on a disposable food-safety sensor is a low-cost, aerosol-jet-printing technology that’s precise enough to create the high-resolution electrodes necessary for electrochemical sensors to detect small molecules such as histamine.

“This fine resolution is important,” said Jonathan Claussen, an associate professor of mechanical engineering at Iowa State University and one of the leaders of the research project. “The closer we can print these electrode fingers, in general, the higher the sensitivity of these biosensors.”

Claussen and the other project leaders – Carmen Gomes, an associate professor of mechanical engineering at Iowa State; and Mark Hersam, the Walter P. Murphy Professor of Materials Science and Engineering at Northwestern University in Evanston, Illinois – have recently reported their sensor discovery in a paper published online by the journal 2D Materials. (…)

The paper describes how graphene electrodes were aerosol jet printed on a flexible polymer and then converted to histamine sensors by chemically binding histamine antibodies to the graphene. The antibodies specifically bind histamine molecules.

The histamine blocks electron transfer and increases electrical resistance, Gomes said. That change in resistance can be measured and recorded by the sensor.

“This histamine sensor is not only for fish,” Gomes said. “Bacteria in food produce histamine. So it can be a good indicator of the shelf life of food.”

The researchers believe the concept will work to detect other kinds of molecules, too.

“Beyond the histamine case study presented here, the (aerosol jet printing) and functionalization process can likely be generalized to a diverse range of sensing applications including environmental toxin detection, foodborne pathogen detection, wearable health monitoring, and health diagnostics,” they wrote in their research paper.

For example, by switching the antibodies bonded to the printed sensors, they could detect salmonella bacteria, or cancers or animal diseases such as avian influenza, the researchers wrote.

Claussen, Hersam and other collaborators (…) have demonstrated broader application of the technology by modifying the aerosol-jet-printed sensors to detect cytokines, or markers of inflammation. The sensors, as reported in a recent paper published by ACS Applied Materials & Interfaces, can monitor immune system function in cattle and detect deadly and contagious paratuberculosis at early stages.

Claussen, who has been working with printed graphene for years, said the sensors have another characteristic that makes them very useful: They don’t cost a lot of money and can be scaled up for mass production.

“Any food sensor has to be really cheap,” Gomes said. “You have to test a lot of food samples and you can’t add a lot of cost.”

Claussen and Gomes know something about the food industry and how it tests for food safety. Claussen is chief scientific officer and Gomes is chief research officer for NanoSpy Inc., a startup company based in the Iowa State University Research Park that sells biosensors to food processing companies.

They said the company is in the process of licensing this new histamine and cytokine sensor technology.

It, after all, is what they’re looking for in a commercial sensor. “This,” Claussen said, “is a cheap, scalable, biosensor platform.”

Here’s a link to and a citation for the two papers mentioned in the news release,

Aerosol-jet-printed graphene electrochemical histamine sensors for food safety monitoring by Kshama Parate, Cícero C Pola, Sonal V Rangnekar, Deyny L Mendivelso-Perez, Emily A Smith, Mark C Hersam, Carmen L Gomes and Jonathan C Claussen. 2D Materials, Volume 7, Number 3 DOI https://doi.org/10.1088/2053-1583/ab8919 Published 10 June 2020 • © 2020 IOP Publishing Ltd

Aerosol-Jet-Printed Graphene Immunosensor for Label-Free Cytokine Monitoring in Serum by Kshama Parate, Sonal V. Rangnekar, Dapeng Jing, Deyny L. Mendivelso-Perez, Shaowei Ding, Ethan B. Secor, Emily A. Smith, Jesse M. Hostetter, Mark C. Hersam, and Jonathan C. Claussen. ACS Appl. Mater. Interfaces 2020, 12, 7, 8592–8603 DOI: https://doi.org/10.1021/acsami.9b22183 Publication Date: February 10, 2020 Copyright © 2020 American Chemical Society

Both papers are behind paywalls.

You can find the NanoSpy website here.

New capacitor for better wearable electronics?

Supercapacitors are a predictable source of scientific interest and excitement. The latest entry in the ‘supercapacitor stakes’ is from a Russian/Finnish/US team according to a June 11, 2020 Skoltech (Skolkovo Institute of Science and Technology) press release (also on EurekAlert),

Researchers from Skoltech [Russia], Aalto University [Finland] and Massachusetts Institute of Technology [MIT; US] have designed a high-performance, low-cost, environmentally friendly, and stretchable supercapacitor that can potentially be used in wearable electronics. The paper was published in the Journal of Energy Storage.

Supercapacitors, with their high power density, fast charge-discharge rates, long cycle life, and cost-effectiveness, are a promising power source for everything from mobile and wearable electronics to electric vehicles. However, combining high energy density, safety, and eco-friendliness in one supercapacitor suitable for small devices has been rather challenging.

“Usually, organic solvents are used to increase the energy density. These are hazardous, not environmentally friendly, and they reduce the power density compared to aqueous electrolytes with higher conductivity,” says Professor Tanja Kallio from Aalto University, a co-author of the paper.

The researchers proposed a new design for a “green” and simple-to-fabricate supercapacitor. It consists of a solid-state material based on nitrogen-doped graphene flake electrodes distributed in the NaCl-containing hydrogel electrolyte. This structure is sandwiched between two single-walled carbon nanotube film current collectors, which provides stretchability. Hydrogel in the supercapacitor design enables compact packing and high energy density and allows them to use the environmentally friendly electrolyte.

The scientists managed to improve the volumetric capacitive performance, high energy density and power density for the prototype over analogous supercapacitors described in previous research. “We fabricated a prototype with unchanged performance under the 50% strain after a thousand stretching cycles. To ensure lower cost and better environmental performance, we used a NaCl-based electrolyte. Still the fabrication cost can be lowered down by implementation of 3D printing or other advanced fabrication techniques,” concluded Skoltech professor Albert Nasibulin.

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

Superior environmentally friendly stretchable supercapacitor based on nitrogen-doped graphene/hydrogel and single-walled carbon nanotubes by Evgeniia Gilshtein, Cristina Flox, Farhan S.M. Ali, Bahareh Mehrabimatin, Fedor S.Fedorov, Shaoting Lin, Xuanhe Zhao, Albert G. Nasibulin, Tanja Kallio. Journal of Energy Storage Volume 30, August 2020, 101505 DOI: https://doi.org/10.1016/j.est.2020.101505

This paper is behind a paywall.

I’m trying to remember if I’ve ever before seen a material that combines graphene and single-walled carbon nanotubes (SWCNTs). Anyway, here’s an image the researchers are using illustrate their work,

Caption: This is an outline of the new supercapacitor. Credit: Pavel Odinev / Skoltech

Improving bacteria detection with the ‘unboil an egg’ machine

Vortex Fluidic Device (VFD) is the technical name for the more familiarly known ‘unboil an egg machine’ and, these days, it’s being used in research to improve bacteria detection. A June 23, 2020 news item on Nanowerk announces the research (Note: A link has been removed),

The versatility of the Vortex Fluidic Device (VFD), a device that famously unboiled an egg, continues to impress, with the innovative green chemistry device created at Flinders University having more than 100 applications – including the creation of a new non-toxic fluorescent dye that detects bacteria harmful to humans.

Traditional fluorescent dyes to examine bacteria viability are toxic and suffer poor photostability – but using the VFD has enabled the preparation of a new generation of aggregation-induced emission dye (AIE) luminogens using graphene oxide (GO), thanks to collaborative research between Flinders University’s Institute for NanoScale Science and Technology and the Centre for Health Technologies, University of Technology Sydney.

Using the VFD to produce GO/AIE probes with the property of high fluorescence is without precedent – with the new GO/AIE nanoprobe having 1400% brighter high fluorescent performance than AIE luminogen alone (Materials Chemistry Frontiers, “Vortex fluidic enabling and significantly boosting light intensity of graphene oxide with aggregation induced emission luminogen”).

A June 24, 2020 Flinders University [Australia] press release, which originated the news item, delves further into the work,

“It’s crucial to develop highly sensitive ways of detecting bacteria that pose a potential threat to humans at the early stage, so health sectors and governments can be informed promptly, to act quickly and efficiently,” says Flinders University researcher Professor Youhong Tang.

“Our GO/AIE nanoprobe will significantly enhance long-term tracking of bacteria to effectively control hospital infections, as well as developing new and more efficient antibacterial compounds.”

The VFD is a new type of chemical processing tool, capable of instigating chemical reactivity, enabling the controlled processing of materials such as mesoporous silica, and effective in protein folding under continuous flow, which is important in the pharmaceutical industry. It continues to impress researchers for its adaptability in green chemistry innovations.

“Developing such a deep understanding of bacterial viability is important to revise infection control policies and invent effective antibacterial compounds,” says lead author of the research, Dr Javad Tavakoli, a previous researcher from Professor Youhong Tang’s group, and now working at the University of Technology Sydney.

“The beauty of this research was developing a highly bright fluorescence dye based on graphene oxide, which has been well recognised as an effective fluorescence quenching material.”

The type of AIE luminogen was first developed in 2015 to enable long-term monitoring of bacterial viability, however, increasing its brightness to increase sensitivity and efficiency remained a difficult challenge. Previous attempts to produce AIE luminogen with high brightness proved very time-consuming, requires complex chemistry, and involves catalysts rendering their mass production expensive.

By comparison, the Vortex Fluidic Device allows swift and efficient processing beyond batch production and the potential for cost-effective commercialisation.

Increasing the fluorescent property of GO/AIE depends on the concentration of graphene oxide, the rotation speed of the VFD tube, and the water fraction in the compound – so preparing GO/AIE under the shear stress induced by the VFD’s high-speed rotating tube resulted in much brighter probes with significantly enhanced fluorescent intensities.

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

Vortex fluidic enabling and significantly boosting light intensity of graphene oxide with aggregation induced emission luminogen by Javad Tavakoli, Nikita Joseph, Clarence Chuah, Colin L. Raston and Youhong Tang. Mater. Chem. Front., [Materials Chemistry Frontiers] 2020, Advance Article DOI: https://doi.org/10.1039/D0QM00270D First published: 28 May 2020

This paper is behind a paywall.

I first marveled about the VFD (unboil an egg machine) in a March 16, 2016 posting.

Architecture, the practice of science, and meaning

The 1979 book, Laboratory Life: the Social Construction of Scientific Facts by Bruno Latour and Steve Woolgar immediately came to mind on reading about a new book (The New Architecture of Science: Learning from Graphene) linking architecture to the practice of science (research on graphene). It turns out that one of the authors studied with Latour. (For more about laboratory Life see: Bruno Latour’s Wikipedia entry; scroll down to Main Works)

A June 19, 2020 news item on Nanowerk announces the new book (Note: A link has been removed),

How does the architecture of scientific buildings matter for science? How does the design of specific spaces such as laboratories, gas rooms, transportation roots, atria, meeting spaces, clean rooms, utilities blocks and mechanical workshops affect how scientists think, conduct experiments, interact and collaborate? What does it mean to design a science lab today? What are the new challenges for the architects of science buildings? And what is the best method to study the constantly evolving architectures of science?

Over the past four decades, the design of lab buildings has drawn the attention of scholars from different disciplines. Yet, existing research tends to focus either purely on the technical side of lab design or on the human interface and communication aspects.

To grasp the specificity of the new generation of scientific buildings, however, a more refined gaze is needed: one that accounts simultaneously for the complex technical infrastructure and the variability of human experience that it facilitates.

Weaving together two tales of the NGI [National Graphene Institute] building in Manchester, lead scientist and one of the designers, Kostya [or Konstantin] Novoselov, and architectural anthropologist, Albena Yaneva, combine an analysis of its distinctive design features with ethnographic observation of the practices of scientists, facility managers, technicians, administrators and house service staff in The New Architecture of Science: Learning from Graphene.

A June 19 (?), 2020 World Scientific press release (also on EurekAlert), which originated the news item, provides more insight into the book’s ambitions,

Drawing on a meticulous study of ‘the social life’ of the building, the book offers a fresh account of the mutual shaping of architecture and science at the intersection of scientific studies, cognitive anthropology and architectural theory. By bringing the voices of the scientist as a client and the architectural theorist into a dual narrative, The New Architecture of Science presents novel insights on the new generation of science buildings.

Glimpses into aspects of the ‘life’ of a scientific building and the complex sociotechnical and collective processes of design and dwelling, as well as into the practices of nanoscientists, will fascinate a larger audience of students across the fields of Architecture, Public Communication of Science, Science and Technology Studies, Physics, Material Science, Chemistry.

The volume is expected to appeal to academic faculty members looking for ways to teach architecture beyond authorship and seeking instead to develop a more comprehensive perspective of the built environment in its complexity of material and social meanings. The book can thus be used for undergraduate and post-graduate course syllabi on the theory of architecture, design and urban studies, science and technology studies, and science communication. It will be a valuable guidebook for innovative studio projects and an inspirational reading for live project courses.

The New Architecture of Science: Learning from Graphene retails for US$49 / £45 (hardcover). To order or know more about the book, visit http://www.worldscientific.com/worldscibooks/10.1142/11840.

The building and the architects

Here’s what it looks like,

©DanielShearing Jestico + Whiles

In addition to occasioning a book, the building has also garnered an engineering award for Jestico + Whiles according to a page dedicated to the UK’s National Institute of Graphene on theplan.it website. Whoever wrote this did an excellent job of reviewing the history of graphene and its relation to the University of Manchester and provides considerable insight into the thinking behind the design and construction of this building,

The RIBA [Royal Institute of British Architects] award-winning National Graphene Institute (NGI) is a world-leading research and incubator centre dedicated to the development of graphene. Located in Manchester, it is an essential component in the UK’s bid to remain at the forefront of the commercialisation of this pioneering and revolutionary material.

Jestico + Whiles was appointed lead architect of the new National Graphene Institute at the University of Manchester in 2012, working closely with Sir Kostya Novoselov – who, along with Sir Andre Geim, first isolated graphene at the University of Manchester in 2004. The two were jointly awarded the Nobel Prize in Physics in 2010. [emphases mine]

Located in the university campus’ science quarter, the institute is housed in a compact 7,600m2 five-storey building, with the main cleanroom located on the lower ground floor to achieve best vibration performance. The ceiling of the viewing corridor that wraps around the cleanroom is cleverly angled so that scientists in the basement are visible to the public from street level.

On the insistence of Professor Novoselov most of the laboratories, including the cleanrooms, have natural daylight and view, to ensure that the intense work schedules do not deprive researchers of awareness and enjoyment of external conditions. All offices are naturally ventilated with openable windows controlled by occupants. Offices and labs on all floors are intermixed to create flexible and autonomous working zones which are easily changed and adapted to suit emerging new directions of research and changing team structures, including invited industry collaborators.

The building also provides generous collaborative and breakout spaces for meetings, relaxation and social interaction, including a double height roof-lit atrium and a top-floor multifunction seminar room/café that opens onto a south facing roof terrace with a biodiverse garden. A special design feature that has been incorporated to promote and facilitate informal exchanges of ideas is the full-height ‘writable’ walls along the corridors – a black PVC cladding that functions like traditional blackboards but obviates the health and safety issue of chalk dust.

The appearance and imagery of this building was of high importance to the client, who recognised the significant impact a cutting-edge research facility for such a potentially world-changing material could bring to the university. Nobel laureate end users, heads of departments, the Estates Directorate, and different members of the design and project team all made contributions to deciding what this was. Speaking in an article in the New Yorker, fellow graphene researcher James Tour of Rice University, Texas said ‘What Andre Geim and Kostya Novoselov did was to show the world the amazingness of graphene.’ Our design sought to convey this ‘amazingness’ through the imagery and materiality of the NGI.

The material chosen for the outer veil is a black Rimex stainless steel, which has the quality of mirror-like reflectivity, but infinitely varies in colour depending on light conditions and the angle of the view. The resulting image is that of a mysterious, ever-changing mirage that evokes the universal experience of scientific exploration. An exploration enveloped by a 2D, ultra-thin, black material that has a mercurial, undefinable character – a perfect visual reference for graphene.

This mystery is deepened by subtle delineation of the equations used in graphene research all over the façade through perforations in the panels. These are intentionally obscure and only apparent upon inspection. The equations include two hidden deliberate mistakes set by Professor Novoselov.

The perforations themselves are hexagonal in shape, representing the 2D atomic formation of graphene. They are laser cut based on a completely regular orthogonal grid, with only the variations in the size of each hole making the pattern of the letters and symbols of the equations. We believe this is a unique design in using parametric design tools to generate organic and random looking patterns out of a completely regular grid.

Who are Albena Yaneva and Sir Konstantin (Kostya) Sergeevich Novoselov?

Yaneva is the author who studied with Latour as you can see in this excerpt from her Univerisiy of Manchester faculty webpage,

After a PhD in Sociology and Anthropology from Ecole Nationale Supérieure des mines de Paris (2001) with Professor Bruno Latour, Yaneva has worked at Harvard University, the Max-Planck Institite for the History of Science in Berlin and the Austrian Academy of Science in Vienna. Her research is intrinsically transdisciplinary and spans the boundaries of science studies, cognitive anthropology, architectural theory and political philosophy. Her work has been translated in German, Italian, Spanish, Portuguese, French, Thai, Polish, Turkish and Japanese.  

Her book The Making of a Building: A Pragmatist Approach to Architecture (Oxford: Peter Lang, 2009) provides a unique anthropological account of architecture in the making, whereas Made by the OMA: An Ethnography of Design (Rotterdam: 010 Publishers, 2009) draws on an original approach of ethnography of design and was defined by the critics as “revolutionary in analyzing the day-to-day practice of designers.” For her innovative use of ethnography in the architectural discourses Yaneva was awarded the RIBA President’s Award for Outstanding University-located Research (2010).

Yaneva’s book Mapping Controversies in Architecture (Routledge, 2012) brought the newest developments in social sciences into architectural theory. It introduced Mapping Controversies as a research and teaching methodology for following design debates. A recent volume in collaboration with Alejandro Zaera-Polo What is Cosmopolitical Design? (Routledge, 2015) questioned the role of architectural design at the time of the Anthropocene and provided many examples of cosmopolitically correct design.  

Her monograph Five Ways to Make Architecture Political. An Introduction to the Politics of Design Practice (Bloomsbury, 2017) takes inspiration from object-oriented political thought and engages in an informed enquiry into the different ways architectural design can be political. The study contributes to a better understanding of the political outreach of the engagement of designers with their publics.  

Professor Yaneva’s monograph Crafting History: Archiving and the Quest for ArchitecturalLegacy (Cornell University Press, 2020) explores the daily practices of archiving in its mundane and practical course and is based on ethnographic observation of the Canadian Centre for Architecture (CCA) [emphasis mine] in Montreal, a leading archival institution, and interviews with a range of practitioners around the world, including Álvaro Siza and Peter Eisenman. Unravelling the multiple epistemic dimensions of archiving, the book tells a powerful story about how collections form the basis of Architectural History. 

I did not expect any Canadian content!

Oddly, I cannot find anything nearly as expansive for Novoselov on the University of Manchester website. There’s this rather concise faculty webpage and this more fulsome biography on the National Graphene Institute website. For the record, he’s a physicist.

For the most detail about his career in physics, I suggest the Konstantin Novoselov Wikipedia entry which includes this bit about his involvement in art,

Novoselov is known for his interest in art.[61] He practices in Chinese traditional drawing[62] and has been involved in several projects on modern art.[63] Thus, in February 2015 he combined forces with Cornelia Parker to create a display for the opening of the Whitworth Art Gallery. Cornelia Parker’s meteorite shower firework (pieces of meteorites loaded in firework) was launched by Novoselov breathing on graphene gas sensor (which changed the resistance of graphene due to doping by water vapour). Graphene was obtained through exfoliation of graphite which was extracted from a drawing of William Blake. Novoselov suggested that he also exfoliated graphite obtained from the drawings of other prominent artists: John Constable, Pablo Picasso, J. M. W. Turner, Thomas Girtin. He said that only microscopic amounts (flake size less than 100 micrometres) was extracted from each of the drawings.[63] In 2015 he participated in “in conversation” session with Douglas Gordon during Interdependence session at Manchester International Festival.[64]

I have published two posts about Novoselov’s participation in art/science projects, the first was on August 13, 2018 and titled: “See Nobel prize winner’s (Kostya Novoselov) collaborative art/science video project on August 17, 2018 (Manchester, UK)” and the second was in February 25, 2019 and titled: “Watch a Physics Nobel Laureate make art on February 26, 2019 at Mobile World Congress 19 in Barcelona, Spain.” (I may have to seriously consider more variety in my titles.)

I hope that one of these days I’ll get my hands on this book. In the meantime, I intend to spend more time perusing Bruno Latour’s website.

Regulating body temperature, graphene-style

I find some illustrations a little difficult to decipher,

Caption: Graphene thermal smart materials. Credit: The University of Manchester

I believe the red in the ‘on/off’ images, signifies heat from the surrounding environment and is not an indicator for body heat and the yellow square in the ‘on’ image indicates the shirt is working and repelling that heat.

Moving on, a June 18, 2020 news item on Nanowerk describes this latest work on a smart textile that can help regulate body temperature when it’s hot,

New research on the two-dimensional (2D) material graphene has allowed researchers to create smart adaptive clothing which can lower the body temperature of the wearer in hot climates.

A team of scientists from The University of Manchester’s National Graphene Institute have created a prototype garment to demonstrate dynamic thermal radiation control within a piece of clothing by utilising the remarkable thermal properties and flexibility of graphene. The development also opens the door to new applications such as, interactive infrared displays and covert infrared communication on textiles.

A June 18, 2020 University of Manchester press release (also on EurekAlert), which originated the news item, provides more detail,

The human body radiates energy in the form of electromagnetic waves in the infrared spectrum (known as blackbody radiation). In a hot climate it is desirable to make use the full extent of the infrared radiation to lower the body temperature that can be achieved by using infrared-transparent textiles. As for the opposite case, infrared-blocking covers are ideal to minimise the energy loss from the body. Emergency blankets are a common example used to deal with treating extreme cases of body temperature fluctuation.

The collaborative team of scientists demonstrated the dynamic transition between two opposite states by electrically tuning the infrared emissivity (the ability to radiate energy) of the graphene layers integrated onto textiles.

One-atom thick graphene was first isolated and explored in 2004 at The University of Manchester. Its potential uses are vast and research has already led to leaps forward in commercial products including; batteries, mobile phones, sporting goods and automotive.

The new research published today in journal Nano Letters, demonstrates that the smart optical textile technology can change its thermal visibility. The technology uses graphene layers to control of thermal radiation from textile surfaces.

Professor Coskun Kocabas, who led the research, said: “Ability to control the thermal radiation is a key necessity for several critical applications such as temperature management of the body in excessive temperature climates. Thermal blankets are a common example used for this purpose. However, maintaining these functionalities as the surroundings heats up or cools down has been an outstanding challenge.”

Prof Kocabas added: “The successful demonstration of the modulation of optical properties on different forms of textile can leverage the ubiquitous use of fibrous architectures and enable new technologies operating in the infrared and other regions of the electromagnetic spectrum for applications including textile displays, communication, adaptive space suits, and fashion”.

This study built on the same group’s previous research using graphene to create thermal camouflage which would fool infrared cameras. The new research can also be integrated into existing mass-manufacture textile materials such as cotton. To demonstrate, the team developed a prototype product within a t-shirt allowing the wearer to project coded messages invisible to the naked eye but readable by infrared cameras.

“We believe that our results are timely showing the possibility of turning the exceptional optical properties of graphene into novel enabling technologies. The demonstrated capabilities cannot be achieved with conventional materials.”

“The next step for this area of research is to address the need for dynamic thermal management of earth-orbiting satellites. Satellites in orbit experience excesses of temperature, when they face the sun, and they freeze in the earth’s shadow. Our technology could enable dynamic thermal management of satellites by controlling the thermal radiation and regulate the satellite temperature on demand.” said Kocabas.

Professor Sir Kostya Novoselov was also involved in the research: “This is a beautiful effect, intrinsically routed in the unique band structure of graphene. It is really exciting to see that such effects give rise to the high-tech applications.” he said.

Advanced materials is one of The University of Manchester’s research beacons – examples of pioneering discoveries, interdisciplinary collaboration and cross-sector partnerships that are tackling some of the biggest questions facing the planet. #ResearchBeacons

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

Graphene-Enabled Adaptive Infrared Textiles by M. Said Ergoktas, Gokhan Bakan, Pietro Steiner, Cian Bartlam, Yury Malevich, Elif Ozden-Yenigun, Guanliang He, Nazmul Karim, Pietro Cataldi, Mark A. Bissett, Ian A. Kinloch, Kostya S. Novoselov, and Coskun Kocabas. Nano Lett. 2020, XXXX, XXX, XXX-XXX DOI: https://doi.org/10.1021/acs.nanolett.0c01694 Publication Date:June 18, 2020 Copyright © 2020 American Chemical Society

This paper is behind a paywall.

Canadian and Italian researchers go beyond graphene with 2D polymers

According to a May 20,2020 McGill University news release (also on EurkekAltert), a team of Canadian and Italian researchers has broken new ground in materials science (Note: There’s a press release I found a bit more accessible and therefore informative coming up after this one),

A study by a team of researchers from Canada and Italy recently published in Nature Materials could usher in a revolutionary development in materials science, leading to big changes in the way companies create modern electronics.

The goal was to develop two-dimensional materials, which are a single atomic layer thick, with added functionality to extend the revolutionary developments in materials science that started with the discovery of graphene in 2004.

In total, 19 authors worked on this paper from INRS [Institut National de la Recherche Scientifique], McGill {University], Lakehead [University], and Consiglio Nazionale delle Ricerche, the national research council in Italy.

This work opens exciting new directions, both theoretical and experimental. The integration of this system into a device (e.g. transistors) may lead to outstanding performances. In addition, these results will foster more studies on a wide range of two-dimensional conjugated polymers with different lattice symmetries, thereby gaining further insights into the structure vs. properties of these systems.

The Italian/Canadian team demonstrated the synthesis of large-scale two-dimensional conjugated polymers, also thoroughly characterizing their electronic properties. They achieved success by combining the complementary expertise of organic chemists and surface scientists.

“This work represents an exciting development in the realization of functional two-dimensional materials beyond graphene,” said Mark Gallagher, a Physics professor at Lakehead University.

“I found it particularly rewarding to participate in this collaboration, which allowed us to combine our expertise in organic chemistry, condensed matter physics, and materials science to achieve our goals.”

Dmytro Perepichka, a professor and chair of Chemistry at McGill University, said they have been working on this research for a long time.

“Structurally reconfigurable two-dimensional conjugated polymers can give a new breadth to applications of two-dimensional materials in electronics,” Perepichka said.

“We started dreaming of them more than 15 years ago. It’s only through this four-way collaboration, across the country and between the continents, that this dream has become the reality.”

Federico Rosei, a professor at the Énergie Matériaux Télécommunications Research Centre of the Institut National de la Recherche Scientifique (INRS) in Varennes who holds the Canada Research Chair in Nanostructured Materials since 2016, said they are excited about the results of this collaboration.

“These results provide new insights into mechanisms of surface reactions at a fundamental level and simultaneously yield a novel material with outstanding properties, whose existence had only been predicted theoretically until now,” he said.

About this study

Synthesis of mesoscale ordered two-dimensional π-conjugated polymers with semiconducting properties” by G. Galeotti et al. was published in Nature Materials.

This research was partially supported by a project Grande Rilevanza Italy-Quebec of the Italian Ministero degli Affari Esteri e della Cooperazione Internazionale, Direzione Generale per la Promozione del Sistema Paese, the Natural Sciences and Engineering Research Council of Canada, the Fonds Québécois de la recherche sur la nature et les technologies and a US Army Research Office. Federico Rosei is also grateful to the Canada Research Chairs program for funding and partial salary support.

About McGill University

Founded in Montreal, Quebec, in 1821, McGill is a leading Canadian post-secondary institution. It has two campuses, 11 faculties, 13 professional schools, 300 programs of study and over 40,000 students, including more than 10,200 graduate students. McGill attracts students from over 150 countries around the world, its 12,800 international students making up 31% per cent of the student body. Over half of McGill students claim a first language other than English, including approximately 19% of our students who say French is their mother tongue.

About the INRS
The Institut National de la Recherche Scientifique (INRS) is the only institution in Québec dedicated exclusively to graduate level university research and training. The impacts of its faculty and students are felt around the world. INRS proudly contributes to societal progress in partnership with industry and community stakeholders, both through its discoveries and by training new researchers and technicians to deliver scientific, social, and technological breakthroughs in the future.

Lakehead University
Lakehead University is a fully comprehensive university with approximately 9,700 full-time equivalent students and over 2,000 faculty and staff at two campuses in Orillia and Thunder Bay, Ontario. Lakehead has 10 faculties, including Business Administration, Education, Engineering, Graduate Studies, Health & Behavioural Sciences, Law, Natural Resources Management, the Northern Ontario School of Medicine, Science & Environmental Studies, and Social Sciences & Humanities. In 2019, Maclean’s 2020 University Rankings, once again, included Lakehead University among Canada’s Top 10 primarily undergraduate universities, while Research Infosource named Lakehead ‘Research University of the Year’ in its category for the fifth consecutive year. Visit www.lakeheadu.ca

I’m a little surprised there wasn’t a quote from one of the Italian researchers in the McGill news release but then there isn’t a quote in this slightly more accessible May 18, 2020 Consiglio Nazionale delle Ricerche press release either,

Graphene’s isolation took the world by surprise and was meant to revolutionize modern electronics. However, it was soon realized that its intrinsic properties limit the utilization in our daily electronic devices. When a concept of Mathematics, namely Topology, met the field of on-surface chemistry, new materials with exotic features were theoretically discovered. Topological materials exhibit technological relevant properties such as quantum hall conductivity that are protected by a concept similar to the comparison of a coffee mug and a donut.  These structures can be synthesized by the versatile molecular engineering toolbox that surface reactions provide. Nevertheless, the realization of such a material yields access to properties that suit the figure of merits for modern electronic application and could eventually for example lead to solve the ever-increasing heat conflict in chip design. However, problems such as low crystallinity and defect rich structures prevented the experimental observation and kept it for more than a decade a playground only investigated theoretically.

An international team of scientists from Institut National de la Recherche Scientifique (Centre Energie, Matériaux et Télécommunications), McGill University and Lakehead University, both located in Canada, and the SAMOS laboratory of the Istituto di Struttura della Materia (Cnr), led by Giorgio Contini, demonstrates, in a recent publication on Nature Materials, that the synthesis of two-dimensional π-conjugated polymers with topological Dirac cone and flats bands became a reality allowing a sneak peek into the world of organic topological materials.

Complementary work of organic chemists and surface scientists lead to two-dimensional polymers on a mesoscopic scale and granted access to their electronic properties. The band structure of the topological polymer reveals both flat bands and a Dirac cone confirming the prediction of theory. The observed coexistence of both structures is of particular interest, since whereas Dirac cones yield massless charge carriers (a band velocity of the same order of magnitude of graphene has been obtained), necessary for technological applications, flat bands quench the kinetic energy of charge carriers and could give rise to intriguing phenomena such as the anomalous Hall effect, surface superconductivity or superfluid transport.

This work paths multiple new roads – both theoretical and experimental nature. The integration of this topological polymer into a device such as transistors possibly reveals immense performance. On the other hand, it will foster many researchers to explore a wide range of two-dimensional polymers with different lattice symmetries, obtaining insight into the relationship between geometrical and electrical topology, which would in return be beneficial to fine tune a-priori theoretical studies. These materials – beyond graphene – could be then used for both their intrinsic properties as well as their interplay in new heterostructure designs.

The authors are currently exploring the practical use of the realized material trying to integrate it into transistors, pushing toward a complete designing of artificial topological lattices.

This work was partially supported by a project Grande Rilevanza Italy-Quebec of the Italian Ministero degli Affari Esteri e della Cooperazione Internazionale (MAECI), Direzione Generale per la Promozione del Sistema Paese.

The Italians also included an image to accompany their press release,

Image of the synthesized material and its band structure Courtesy: Consiglio Nazionale delle Ricerche

My heart sank when I saw the number of authors for this paper (WordPress no longer [since their Christmas 2018 update] makes it easy to add the author’s names quickly to the ‘tags field’). Regardless and in keeping with my practice, here’s a link to and a citation for the paper,

Synthesis of mesoscale ordered two-dimensional π-conjugated polymers with semiconducting properties by G. Galeotti, F. De Marchi, E. Hamzehpoor, O. MacLean, M. Rajeswara Rao, Y. Chen, L. V. Besteiro, D. Dettmann, L. Ferrari, F. Frezza, P. M. Sheverdyaeva, R. Liu, A. K. Kundu, P. Moras, M. Ebrahimi, M. C. Gallagher, F. Rosei, D. F. Perepichka & G. Contini. Nature Materials (2020) DOI: https://doi.org/10.1038/s41563-020-0682-z Published 18 May 2020

This paper is behind a paywall.

Flexible graphene-rubber sensor for wearables

Courtesy: University of Waterloo

This waffled, greyish thing may not look like much but scientists are hopeful that it can be useful as a health sensor in athletic shoes and elsewhere. A March 6, 2020 news item on Nanowerk describes the work in more detail (Note: Links have been removed),

Researchers have utilized 3D printing and nanotechnology to create a durable, flexible sensor for wearable devices to monitor everything from vital signs to athletic performance (ACS Nano, “3D-Printed Ultra-Robust Surface-Doped Porous Silicone Sensors for Wearable Biomonitoring”).

The new technology, developed by engineers at the University of Waterloo [Ontario, Canada], combines silicone rubber with ultra-thin layers of graphene in a material ideal for making wristbands or insoles in running shoes.

A March 6, 2020 University of Waterloo news release, which originated the news item, delves further,

When that rubber material bends or moves, electrical signals are created by the highly conductive, nanoscale graphene embedded within its engineered honeycomb structure.

“Silicone gives us the flexibility and durability required for biomonitoring applications, and the added, embedded graphene makes it an effective sensor,” said Ehsan Toyserkani, research director at the Multi-Scale Additive Manufacturing (MSAM) Lab at Waterloo. “It’s all together in a single part.”

Fabricating a silicone rubber structure with such complex internal features is only possible using state-of-the-art 3D printing – also known as additive manufacturing – equipment and processes.

The rubber-graphene material is extremely flexible and durable in addition to highly conductive.

“It can be used in the harshest environments, in extreme temperatures and humidity,” said Elham Davoodi, an engineering PhD student at Waterloo who led the project. “It could even withstand being washed with your laundry.”

The material and the 3D printing process enable custom-made devices to precisely fit the body shapes of users, while also improving comfort compared to existing wearable devices and reducing manufacturing costs due to simplicity.

Toyserkani, a professor of mechanical and mechatronics engineering, said the rubber-graphene sensor can be paired with electronic components to make wearable devices that record heart and breathing rates, register the forces exerted when athletes run, allow doctors to remotely monitor patients and numerous other potential applications.

Researchers from the University of California, Los Angeles and the University of British Columbia collaborated on the project.

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

3D-Printed Ultra-Robust Surface-Doped Porous Silicone Sensors for Wearable Biomonitoring by Elham Davoodi, Hossein Montazerian, Reihaneh Haghniaz, Armin Rashidi, Samad Ahadian, Amir Sheikhi, Jun Chen, Ali Khademhosseini, Abbas S. Milani, Mina Hoorfar, Ehsan Toyserkani. ACS Nano 2020, 14, 2, 1520-1532 DOI: https://doi.org/10.1021/acsnano.9b06283 Publication Date: January 6, 2020 Copyright © 2020 American Chemical Society

This paper is behind a paywall.

Graphene fatigue

Graphene fatigue operates under the same principle as metal fatigue. Subject graphene to stress over and over and at some point it (just like metal) will fail. Scientists at the University of Toronto (Ontatrio, Canada) and Rice University (Texas, US) have determined just how much stress graphene can withstand before breaking according to a January 28, 2020 University of Toronto news release by Tyler Irving (also on EurekAlert but published on January 29, 2020),

Graphene is a paradox. It is the thinnest material known to science, yet also one of the strongest. Now, research from University of Toronto Engineering shows that graphene is also highly resistant to fatigue — able to withstand more than a billion cycles of high stress before it breaks.

Graphene resembles a sheet of interlocking hexagonal rings, similar to the pattern you might see in bathroom flooring tiles. At each corner is a single carbon atom bonded to its three nearest neighbours. While the sheet could extend laterally over any area, it is only one atom thick.

The intrinsic strength of graphene has been measured at more than 100 gigapascals, among the highest values recorded for any material. But materials don’t always fail because the load exceeds their maximum strength. Stresses that are small but repetitive can weaken materials by causing microscopic dislocations and fractures that slowly accumulate over time, a process known as fatigue.

“To understand fatigue, imagine bending a metal spoon,” says Professor Tobin Filleter, one of the senior authors of the study, which was recently published in Nature Materials. “The first time you bend it, it just deforms. But if you keep working it back and forth, eventually it’s going to break in two.”

The research team — consisting of Filleter, fellow University of Toronto Engineering professors Chandra Veer Singh and Yu Sun, their students, and collaborators at Rice University — wanted to know how graphene would stand up to repeated stresses. Their approach included both physical experiments and computer simulations.

“In our atomistic simulations, we found that cyclic loading can lead to irreversible bond reconfigurations in the graphene lattice, causing catastrophic failure on subsequent loading,” says Singh, who along with postdoctoral fellow Sankha Mukherjee led the modelling portion of the study. “This is unusual behaviour in that while the bonds change, there are no obvious cracks or dislocations, which would usually form in metals, until the moment of failure.”

PhD candidate Teng Cui, who is co-supervised by Filleter and Sun, used the Toronto Nanofabrication Centre to build a physical device for the experiments. The design consisted of a silicon chip etched with half a million tiny holes only a few micrometres in diameter. The graphene sheet was stretched over these holes, like the head of a tiny drum.

Using an atomic force microscope, Cui then lowered a diamond-tipped probe into the hole to push on the graphene sheet, applying anywhere from 20 to 85 per cent of the force that he knew would break the material.

“We ran the cycles at a rate of 100,000 times per second,” says Cui. “Even at 70 per cent of the maximum stress, the graphene didn’t break for more than three hours, which works out to over a billion cycles. At lower stress levels, some of our trials ran for more than 17 hours.”

As with the simulations, the graphene didn’t accumulate cracks or other tell-tale signs of stress — it either broke or it didn’t.

“Unlike metals, there is no progressive damage during fatigue loading of graphene,” says Sun. “Its failure is global and catastrophic, confirming simulation results.”

The team also tested a related material, graphene oxide, which has small groups of atoms such as oxygen and hydrogen bonded to both the top and bottom of the sheet. Its fatigue behaviour was more like traditional materials, in that the failure was more progressive and localized. This suggests that the simple, regular structure of graphene is a major contributor to its unique properties.

“There are no other materials that have been studied under fatigue conditions that behave the way graphene does,” says Filleter. “We’re still working on some new theories to try and understand this.”

In terms of commercial applications, Filleter says that graphene-containing composites — mixtures of conventional plastic and graphene — are already being produced and used in sports equipment such as tennis rackets and skis.

In the future, such materials may begin to be used in cars or in aircraft, where the emphasis on light and strong materials is driven by the need to reduce weight, improve fuel efficiency and enhance environmental performance.

“There have been some studies to suggest that graphene-containing composites offer improved resistance to fatigue, but until now, nobody had measured the fatigue behaviour of the underlying material,” he says. “Our goal in doing this was to get at that fundamental understanding so that in the future, we’ll be able to design composites that work even better.”

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

Fatigue of graphene by Teng Cui, Sankha Mukherjee, Parambath M. Sudeep, Guillaume Colas, Farzin Najafi, Jason Tam, Pulickel M. Ajayan, Chandra Veer Singh, Yu Sun & Tobin Filleter. Nature Materials (2020) DOI: DOIhttps://doi.org/10.1038/s41563-019-0586-y Published: 20 January 2020

This paper is behind a paywall.

Understanding the fundamental limits of graphene electronics by way of a new quantum phenomenon

A July 26, 2019 news item on Nanowerk takes us into the world of quantum physics and graphene (Note: Links have been removed),

A team of researchers from the Universities of Manchester, Nottingham and Loughborough have discovered quantum phenomena that helps to understand the fundamental limits of graphene electronics.

As published in Nature Communications (“Strong magnetophonon oscillations in extra-large graphene”), the work describes how electrons in a single atomically-thin sheet of graphene scatter off the vibrating carbon atoms which make up the hexagonal crystal lattice.

By applying a magnetic field perpendicular to the plane of graphene, the current-carrying electrons are forced to move in closed circular “cyclotron” orbits. In pure graphene, the only way in which an electron can escape from this orbit is by bouncing off a “phonon” in a scattering event. These phonons are particle-like bundles of energy and momentum and are the “quanta” of the sound waves associated with the vibrating carbon atom. The phonons are generated in increasing numbers when the graphene crystal is warmed up from very low temperatures.

By passing a small electrical current through the graphene sheet, the team were able to measure precisely the amount of energy and momentum that is transferred between an electron and a phonon during a scattering event.

A July 26, 2019 University of Manchester press release, which originated the news item, provides additional technical details,

Their experiment revealed that two types of phonon scatter the electrons: transverse acoustic (TA) phonons in which the carbon atoms vibrate perpendicular to the direction of phonon propagation and wave motion (somewhat analogous to surface waves on water) and longitudinal acoustic (LA) phonons in which the carbon atoms vibrate back and forth along the direction of the phonon and the wave motion; (this motion is somewhat analogous to the motion of sound waves through air).

The measurements provide a very accurate measure of the speed of both types of phonons, a measurement which is otherwise difficult to make for the case of a single atomic layer. An important outcome of the experiments is the discovery that TA phonon scattering dominates over LA phonon scattering.

The observed phenomena, commonly referred to as “magnetophonon oscillations”, was measured in many semiconductors years before the discovery of graphene. It is one of the oldest quantum transport phenomena that has been known for more than fifty years, predating the quantum Hall effect. Whereas graphene possesses a number of novel, exotic electronic properties, this rather fundamental phenomenon has remained hidden.

Laurence Eaves & Roshan Krishna Kumar, co-authors of the work said: “We were pleasantly surprised to find such prominent magnetophonon oscillations appearing in graphene. We were also puzzled why people had not seen them before, considering the extensive amount of literature on quantum transport in graphene.”

Their appearance requires two key ingredients. First, the team had to fabricate high quality graphene transistors with large areas at the National Graphene Institute. If the device dimensions are smaller than a few micrometres the phenomena could not be observed.

Piranavan Kumaravadivel from The University of Manchester, lead author of the paper said: “At the beginning of quantum transport experiments, people used to study macroscopic, millimetre sized crystals. In most of the work on quantum transport on graphene, the studied devices are typically only a few micrometres in size. It seems that making larger graphene devices is not only important for applications but now also for fundamental studies.”

The second ingredient is temperature. Most graphene quantum transport experiments are performed at ultra-cold temperatures in-order to slow down the vibrating carbon atoms and “freeze-out” the phonons that usually break quantum coherence. Therefore, the graphene is warmed up as the phonons need to be active to cause the effect.

Mark Greenaway, from Loughborough University, who worked on the quantum theory of this effect said: “This result is extremely exciting – it opens a new route to probe the properties of phonons in two-dimensional crystals and their heterostructures. This will allow us to better understand electron-phonon interactions in these promising materials, understanding which is vital to develop them for use in new devices and applications.”

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

Strong magnetophonon oscillations in extra-large graphene by P. Kumaravadivel, M. T. Greenaway, D. Perello, A. Berdyugin, J. Birkbeck, J. Wengraf, S. Liu, J. H. Edgar, A. K. Geim, L. Eaves & R. Krishna Kumar. ature Communicationsvolume 10, Article number: 3334 (2019) DOI: https://doi.org/10.1038/s41467-019-11379-3 Published 26 July 2019

This paper is open access.

An artificial graphene throat

A July 24, 2019 American Chemical Society (ACS) news release (received via email and also on EurekAlert) describes a ‘tattoo-like- artificial throat derived from graphene,

Most people take speech for granted, but it’s actually a complex process that involves both motions of the mouth and vibrations of folded tissues, called vocal cords, within the throat. If the vocal cords sustain injuries or other lesions, a person can lose the ability to speak. Now, researchers reporting in ACS Nano have developed a wearable artificial throat that, when attached to the neck like a temporary tattoo, can transform throat movements into sounds.

Scientists have developed detectors that measure movements on human skin, such as pulse or heartbeat. However, the devices typically can’t convert these motions into sounds. Recently, He Tian, Yi Yang, Tian-Ling Ren and colleagues developed a prototype artificial throat with both capabilities, but because the device needed to be taped to the skin, it wasn’t comfortable enough to wear for long periods of time. So the researchers wanted to develop a thinner, skin-like artificial throat that would adhere to the neck like a temporary tattoo.

To make their artificial throat, the researchers laser-scribed graphene on a thin sheet of polyvinyl alcohol film. The flexible device measured 0.6 by 1.2 inches, or about double the size of a person’s thumbnail. The researchers used water to attach the film to the skin over a volunteer’s throat and connected it with electrodes to a small armband that contained a circuit board, microcomputer, power amplifier and decoder. When the volunteer noiselessly imitated the throat motions of speech, the instrument converted these movements into emitted sounds, such as the words “OK” and “No.” The researchers say that, in the future, mute people could be trained to generate signals with their throats that the device would translate into speech.

Caption: A wearable artificial graphene throat, abbreviated here as ‘WAGT,’ can transform human throat movements into different sounds with training of the wearer. Credit: Adapted from ACS Nano 2019, 10.1021/acsnano.9b03218

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

A Wearable Skinlike Ultra-Sensitive Artificial Graphene Throat by Yuhong Wei, Yancong Qiao, Guangya Jiang, Yunfan Wang, Fangwei Wang, Mingrui Li, Yunfei Zhao, Ye Tian, Guangyang Gou, Songyao Tan He, Tian, Yi Yang, Tian-Ling Ren. ACS Nano2019XXXXXXXXXX-XXX DOI: https://doi.org/10.1021/acsnano.9b03218 Publication Date: July 3, 2019 Copyright © 2019 American Chemical Society

This paper is behind a paywall.