The price cycle of new technology is often a repetitive one: From eye-wateringly expensive, only available to the early adopters and the big spenders, to radical price slashes that open up a product to the market at large a few years down the line. But what about a radical new technology that is both revolutionary and cheap at the point of release? According to researchers at the Royal Melbourne Institute of Technology (RMIT), Australia, the touchscreens of the future may not just be thin and flexible but far cheaper than current offerings on the market.
Researchers at RMIT claim to have developed a touch-responsive technology that is 100 times thinner than current touchscreen materials, flexible enough to be rolled up like a tube.
The researchers created a new conductive sheet by using a film that is common in mobile phone touchscreens, indium-tin oxide, a film that is transparent and conductive but brittle.
The film was shrunk from 3D to 2D using liquid metal chemistry, heating the indium-tin alloy to 200c to make it into a liquid, rolling over a surface to print off ‘nano-thin’ sheets of indium tin oxide.
The 2D ‘nano-sheets’ have an identical chemical makeup of standard alloy films with a different crystal structure, being compatible with existing electronic devices with the potential to be manufactured through roll-to-roll processing like newspaper due to its flexibility.
The new sheet absorbs 0/7% of light, compared to the 5-10% average of standard conductive glass, being able to made more electronically conductive by adding more layers. The research team have speculated that the material could be used in a variety of optoelectronic applications, including LEDs, touch displays, solar cells and smart windows.
Dr Torben Daeneke, lead researcher, RMIT explained: “You can bend it, you can twist it, and you could make it far more cheaply and efficiently than the slow and expensive way that we currently manufacture touchscreens.
“Turning it two-dimensional also makes it more transparent, so it lets through more light. A touchscreen made of our material would use less power, extending the battery life by roughly 10%.”
The researchers have used the material to create a working touchscreen prototype, with a patent for the technology now pending.
Daeneke said: “We’re excited to be at the stage now where we can explore commercial collaboration opportunities and work with the relevant industries to bring this technology to market.
“There’s no other way of making this fully flexible, conductive and transparent material aside from our new liquid metal method. It was impossible up to now – people just assumed that it couldn’t be done.”
Engineering researchers have developed a device the size of a wristwatch that can monitor an individual’s body chemistry to help improve athletic performance and identify potential health problems. The device can be used for everything from detecting dehydration to tracking athletic recovery, with applications ranging from military training to competitive sports.
“This technology allows us to test for a wide range of metabolites in almost real time,” says Michael Daniele, co-corresponding author of a paper on the work and an assistant professor of electrical and computer engineering at North Carolina State University and in the Joint Department of Biomedical Engineering at NC State and the University of North Carolina at Chapel Hill.
Metabolites are markers that can be monitored to assess an individual’s metabolism. So, if someone’s metabolite levels are outside of normal parameters, it could let trainers or health professionals know that something’s wrong. For athletes, it could also be used to help tailor training efforts to improve physical performance.
“For this proof-of-concept study, we tested sweat from human participants and monitored for glucose, lactate, pH and temperature,” Daniele says.
A replaceable strip on the back of the device is embedded with chemical sensors. That strip rests against a user’s skin, where it comes into contact with the user’s sweat. Data from the sensors in the strip are interpreted by hardware inside the device, which then records the results and relays them to a user’s smartphone or smartwatch.
“The device is the size of an average watch, but contains analytical equipment equivalent to four of the bulky electrochemistry devices currently used to measure metabolite levels in the lab,” Daniele says. “We’ve made something that is truly portable, so that it can be used in the field.”
While the work for this paper focused on measuring glucose, lactate and pH, the sensor strips could be customized to monitor for other substances that can be markers for health and athletic performance — such as electrolytes.
“We’re optimistic that this hardware could enable new technologies to reduce casualties during military or athletic training, by spotting health problems before they become critical,” Daniele says. “It could also improve training by allowing users to track their performance over time. For example, what combination of diet and other variables improves a user’s ability to perform?”
The researchers are now running a study to further test the technology when it is being worn by people under a variety of conditions.
“We want to confirm that it can provide continuous monitoring when in use for an extended period of time,” Daniele says.
“While it’s difficult to estimate what the device might cost consumers, it only costs tens of dollars to make. And the cost of the strips — which can last for at least a day — should be comparable to the glucose strips used by people with diabetes.
“We’re currently looking for industry partners to help us explore commercialization options for this technology,” Daniele says.
- Murat A. Yokus, Tanner Songkakul, Vladimir A. Pozdin, Alper Bozkurt, Michael A. Daniele. Wearable multiplexed biosensor system toward continuous monitoring of metabolites. Biosensors and Bioelectronics, 2020; 153: 112038 DOI: 10.1016/j.bios.2020.112038
New droplet-based electricity generator: A drop of water generates 140V power, lighting up 100 LED bulbs
Generating electricity from raindrops efficiently has gone one step further. A research team led by scientists from the City University of Hong Kong (CityU) has recently developed a droplet-based electricity generator (DEG), featured with a field-effect transistor (FET)-like structure that allows for high energy-conversion efficiency and instantaneous power density increased by thousands times compared to its counterparts without FET-like structure. This would help to advance scientific research of water energy generation and tackle the energy crisis.
The research was led together by Professor Wang Zuankai from CityU’s Department of Mechanical Engineering, Professor Zeng Xiao Cheng from University of Nebraska-Lincoln, and Professor Wang Zhong Lin, Founding Director and Chief Scientist from Beijing Institute of Nanoenergy and Nanosystems of Chinese Academy of Sciences. Their findings were published in the latest issue of journal Nature.
Efficiency of electrical energy conversion greatly improved
Hydropower is nothing new. About 70% of the earth’s surface is covered by water. Yet low-frequency kinetic energy contained in waves, tides, and even raindrops are not efficiently converted into electrical energy due to limitations in current technology. For example, a conventional droplet energy generator based on the triboelectric effect can generate electricity induced by contact electrification and electrostatic induction when a droplet hits a surface. However, the amount of charges generated on the surface is limited by the interfacial effect, and as a result, the energy conversion efficiency is quite low.
In order to improve the conversion efficiency, the research team has spent two years developing the DEG. Its instantaneous power density can reach up to 50.1 W/m2, thousands times higher than other similar devices without the use of FET-like design. And the energy conversion efficiency is markedly higher.
Professor Wang from CityU pointed out that there are two crucial factors for the invention. First, the team found that the continuous droplets impinging on PTFE, an electret material with a quasi-permanent electric charge, provides a new route for the accumulation and storage of high-density surface charges. They found that when water droplets continuously hit the surface of PTFE, the surface charges generated will accumulate and gradually reach a saturation. This new discovery helped to overcome the bottleneck of low charge density encountered in previous work.
Unique field-effect transistor-like structure
Another key feature of their design is a unique set of structures similar to a FET, which is a Nobel Prize in Physics winning innovation in 1956 and has become the basic building block of modern electronic devices nowadays. The device consists of an aluminium electrode, and an indium tin oxide (ITO) electrode with a film of PTFE deposited on it. The PTFE/ITO electrode is responsible for the charge generation, storage, and induction. When a falling water droplet hits and spreads on the PTFE/ITO surface, it naturally “bridges” the aluminium electrode and the PTFE/ITO electrode, translating the original system into a closed-loop electric circuit.
With this special design, a high density of surface charges can be accumulated on the PTFE through continuous droplet impinging. Meanwhile, when the spreading water connects the two electrodes, all the stored charges on the PTFE can be fully released for the generation of electric current. As a result, both the instantaneous power density and energy conversion efficiency are much higher.
“Our research shows that a drop of 100 microlitres (1 microlitre = one-millionth litre) of water released from a height of 15 cm can generate a voltage of over 140V. And the power generated can light up 100 small LED light bulbs,” said Professor Wang.
He added that the increase in instantaneous power density does not result from additional energy, but from the conversion of kinetic energy of water itself. “The kinetic energy entailed in falling water is due to gravity and can be regarded as free and renewable. It should be better utilized.”
Their research also shows that the reduction in relative humidity does not affect the efficiency of power generation. Also, both rainwater and seawater can be used to generate electricity.
Facilitates the sustainability of the world
Professor Wang hoped that the outcome of this research would help to harvest water energy to respond to the global problem of renewable energy shortage. “Generating power from raindrops instead of oil and nuclear energy can facilitate the sustainable development of the world,” he added.
He believed that in the long run, the new design could be applied and installed on different surfaces, where liquid in contact with solid, to fully utilize the low-frequency kinetic energy in water. This can range from the hull surface of ferry, coastline, to the surface of umbrellas or even inside water bottles.
A Ludwig Cancer Research study has devised a new type of chimeric antigen-receptor (CAR) T cell — a family of promising immunotherapies for cancer — that can be switched on and off on demand. The study, led by Melita Irving of the Lausanne Branch of the Ludwig Institute for Cancer Research, George Coukos, director of the Branch, and their colleague Bruno Correia of the École Polytechnique Fédérale de Lausanne (EPFL), addresses a central conundrum of CAR-T therapies: their tendency to provoke potentially deadly runaway immune responses against healthy tissues in patients. Their report appears in the current issue of Nature Biotechnology.
“We wanted to develop a way to dampen CAR-T cell therapy as a safety mechanism in the event of an adverse reaction in a patient,” says Coukos. “To do that we designed CAR-T cells that can be reversibly inactivated with small molecules that can be given systemically and act rapidly.”
CAR-T cells are designed to detect specific molecular markers, or antigens, and destroy the cancer cells that bear them. To that end, researchers engineer a chimeric molecule, expressed on a T cell, that is stitched together from the functional units — or “domains” — of a few key proteins. The external part of the CAR protein does the antigen detecting. The inner part has two other key components. One is the signaling domain of a protein named CD3-zeta that is absolutely required to activate the T cell. The other is the signaling part of another protein, usually CD28, that supports the proliferation and survival of the activated T cell.
These cellular immunotherapies have been approved for the treatment of some blood cancers, and researchers are working on targeting them at solid tumors. But the treatment has significant risks. CAR-T cells can inadvertently elicit cascading, systemic immune reactions known as cytokine release syndrome, which can cause serious side effects.
Researchers have sought to blunt these risks by, for example, engineering CAR-T cells to commit suicide on demand or require a drug to become activated. “The former approach leads, however, to the waste of a very expensive immunotherapy, while the latter has been challenged by the short half-lives of the drugs,” says Irving. “Our approach offers novel and unique solutions to this difficult molecular engineering problem.”
To build their “STOP-CAR-T” system, the researchers stuck the CD3-zeta activation domain on one molecule and the antigen-detecting portion on the another. To link the two chains together, so that they’d function as a single unit, they added to each chain the interacting domains of two unrelated proteins that spontaneously pair up inside the cell. The researchers also ensured that the binding could be disrupted by existing small molecules administered systemically. Elegant computational modeling and protein engineering done in Correia’s laboratory identified ideal molecular partners for these binding domains and ensured that these newly added binding domains would not interfere with the complex protein interactions within the cell required for the signaling that activates T cells.
The researchers first confirmed in cell cultures that this two-protein CAR-T system — targeted to a prostate cancer antigen — worked as well as a similarly targeted but traditionally designed CAR-T system and could be switched off by a drug-like molecule. They then grew tumors expressing that antigen in the flanks of mice and showed that while both types of CAR-T cells could slow tumor growth, only the STOP-CAR-T system’s effects could be abrogated with the administration of the small molecule before or after the initiation of CAR-T therapy.
“This really shows that, in principle, we should be able to directly control the activity of the STOP-CAR T cells in patients,” says Irving.
The researchers are now developing a STOP-CAR-T system that can be controlled by an approved drug and tweaking the system in various ways to see if they can lower the amount of drug required to control the cells.
“This work itself, and its potential, is really exciting,” says Coukos, “but I think it is also illustrative of how well-orchestrated, multidisciplinary collaborations can yield significant scientific breakthroughs. Working with EPFL and our other partners in the region, we hope to bring STOP-CAR-T therapy as quickly as possible to cancer patients.”
This study was supported by Ludwig Cancer Research, the Biltema and ISREC Foundations, the European Research Council, the National Center of Competence for Molecular Systems Engineering, The Marie Sklodowska-Curie Actions, Whitaker and the National Research Foundation of Korea.
- Greta Giordano-Attianese, Pablo Gainza, Elise Gray-Gaillard, Elisabetta Cribioli, Sailan Shui, Seonghoon Kim, Mi-Jeong Kwak, Sabrina Vollers, Angel De Jesus Corria Osorio, Patrick Reichenbach, Jaume Bonet, Byung-Ha Oh, Melita Irving, George Coukos, Bruno E. Correia. A computationally designed chimeric antigen receptor provides a small-molecule safety switch for T-cell therapy. Nature Biotechnology, 2020; DOI: 10.1038/s41587-019-0403-9
Scientists at the University of Groningen and the University Medical Center Groningen used molecular motors to manipulate the protein matrix on which bone marrow-derived mesenchymal stem cells are grown. Rotating motors altered the protein structure, which resulted in a bias of the stem cells to differentiate into bone cells (osteoblasts). Without rotation, the stem cells tended to remain multipotent. These results, which could be used in tissue engineering, were published in Science Advances on 29 January.
‘Cells are sensitive to the structure of the surface that they attach to,’ explains Patrick van Rijn, associate professor in Materiobiology and Nanobiomaterials. ‘And movement is an important driver in biology, especially continuous movement.’ That is why Van Rijn and Feringa and their colleagues decided to use molecular motors to manipulate the protein matrix on which stem cells are grown. The light-driven motor molecules were designed by the 2016 Nobel Laureate in Chemistry Ben Feringa.
The scientists linked molecular motors to a glass surface. Subsequently, the surface was coated with protein and either exposed to UV irradiation to power the motors or not exposed to it at all. After about an hour, the motor movement was stopped and cells were seeded onto the protein layer and left to attach. Finally, differentiation factors were added. These experiments showed that cells grown on protein that was submitted to the rotary motion of the molecular motors tended to specialize into bone cells more often, while cells seeded on protein that was not disturbed were more inclined to maintain their stem-cell properties.
Observations of the protein layer using atomic force microscopy and simulations of the interaction between the motor molecules and proteins, performed by Prof. Marrink’s research group, showed that the movement induced subtle structural changes in the protein matrix. ‘The movement of motor molecules interferes with the alpha-helices in the proteins, which causes structural changes,’ explains Van Rijn. He compares it to the difference in texture between an unwhipped egg white and a whipped one.
The change in the surface structure of the adhered protein affects how the cells attach, for example how much they stretch out. This sets off a signaling cascade that eventually leads to altered behavior, such as the differentiation into bone cells. Thus, molecular movement leads to nanoscopic changes in surface structure, which in turn leads to differences in cell attachment, cell morphology and eventually, cell differentiation. ‘It’s like a domino effect, where smaller stones consecutively topple slightly larger ones so that a large effect can be achieved with a small trigger.’
‘Changing the properties of a surface to affect cell fate has been used before,’ says Van Rijn. However, this was done primarily with switches, so there was just a change from one state to another. ‘In our study, we had continuous movement, which is much more in line with the continuous motion found in biological transport and communication systems. The fact that the motors are driven by light is important,’ Van Rijn adds. ‘Light can be carefully controlled in space and time. This would allow us to create complex geometries in the growth matrix, which then result in different properties for the cells.’ Therefore, light-controlled molecular motors could be a useful tool in tissue engineering.
A recently published paper from the School of Engineering says existing design methods for urban drainage systems aren’t going far enough to withstand possible catastrophic storms or even unpredictable failures during a moderate storm.
“As engineers, we run simulations of possible catastrophic events, and current systems often do not fare well,” says doctoral student Saeed Mohammadiun. “We are seeing sources of overloading such as structural failures, severe rainfalls or abrupt snowmelt stressing these systems.”
Add any extreme situation including quick snowmelt or a heavy and sudden rainfall, and Mohammadiun says many systems aren’t built to handle these worst-case scenarios. Mohammadiun has conducted several case studies of drainage systems in major urban areas around the world. He has determined many current urban standards designed for a 10-to-50 or even 100-year storm scenario are not meeting the increasing demands of climate change as well as intrinsic failure risk of networks’ elements.
“Conventional, reliability-based design methods only provide acceptable performance under expected conditions of loading,” he says. “Depending on the system, if something breaks down or there is a blockage, it can result in a failure and possible flooding.”
According to Mohammadiun, the resiliency of a system is not just dependent on the load it can handle, but also on its design and build. Many do not take into account the effects of climate change or unexpected weather conditions.
To establish an efficient resilient system, Mohammadiun says it is important to consider various sources of uncertainty such as rainfall characteristics, heavy snowfalls followed by a quick melt and different possible malfunction scenarios along with budget constraints, he says.
“Building or improving the resilience of urban stormwater drainage systems is crucial to ensuring these systems are protected against failure as much as possible, or they can quickly recover from a potential failure,” he adds. “This resilient capacity will provide urban drainage systems with the desired adaptability to a wide range of unexpected failures during their service life.”
The research points to several measures municipalities can proactively address the issue. Municipalities could build bypass lines and apply an appropriate combination of relief tunnels, storage units, and other distributed hydraulic structures in order to augment drainage system capacities in a resilient manner.
With the recent heavy snowfalls across Canada, Mohammadiun says the silver lining when it comes to drainage is that it takes snow time to melt whereas heavy rainfall puts an immediate stress on these systems. But from the engineering point of view, it is necessary to consider both acute and chronic conditions.
Not surprising, the research shows that urban drainage and stormwater systems that are built or modified to be more resilient, will handle extreme weather events more effectively and efficiently than conventional designs.
The magnetic, conductive and optical properties of complex oxides make them key to components of next-generation electronics used for data storage, sensing, energy technologies, biomedical devices and many other applications.
Stacking ultrathin complex oxide single-crystal layers — those composed of geometrically arranged atoms — allows researchers to create new structures with hybrid properties and multiple functions. Now, using a new platform developed by engineers at the University of Wisconsin-Madison and the Massachusetts Institute of Technology, researchers will be able to make these stacked-crystal materials in virtually unlimited combinations.
The team published details of its advance Feb. 5 in the journal Nature.
Epitaxy is the process for depositing one material on top of another in an orderly way. The researchers’ new layering method overcomes a major challenge in conventional epitaxy — that each new complex oxide layer must be closely compatible with the atomic structure of the underlying layer. It’s sort of like stacking Lego blocks: The holes on the bottom of one block must align with the raised dots atop the other. If there’s a mismatch, the blocks won’t fit together properly.
“The advantage of the conventional method is that you can grow a perfect single crystal on top of a substrate, but you have a limitation,” says Chang-Beom Eom, a UW-Madison professor of materials science and engineering and physics. “When you grow the next material, your structure has to be the same and your atomic spacing must be similar. That’s a constraint, and beyond that constraint, it doesn’t grow well.”
A couple of years ago, a team of MIT researchers developed an alternate approach. Led by Jeehwan Kim, an associate professor in mechanical engineering and materials science and engineering at MIT, the group added an ultrathin intermediate layer of a unique carbon material called graphene, then used epitaxy to grow a thin semiconducting material layer atop that. Just one molecule thick, the graphene acts like a peel-away backing due to its weak bonding. The researchers could remove the semiconductor layer from the graphene. What remained was a freestanding ultrathin sheet of semiconducting material.
Eom, an expert in complex oxide materials, says they are intriguing because they have a wide range of tunable properties — including multiple properties in one material — that many other materials do not. So, it made sense to apply the peel-away technique to complex oxides, which are much more challenging to grow and integrate.
“If you have this kind of cut-and-paste growth and removal, combined with the different functionality of putting single-crystal oxide materials together, you have a tremendous possibility for making devices and doing science,” says Eom, who connected with mechanical engineers at MIT during a sabbatical there in 2014.
The Eom and Kim research groups combined their expertise to create ultrathin complex oxide single-crystal layers, again using graphene as the peel-away intermediate. More importantly, however, they conquered a previously insurmountable obstacle — the difference in crystal structure — in integrating different complex oxide materials.
“Magnetic materials have one crystal structure, while piezoelectric materials have another,” says Eom. “So you cannot grow them on top of each other. When you try to grow them, it just becomes messy. Now we can grow the layers separately, peel them off, and integrate them.”
In its research, the team demonstrated the efficacy of the technique using materials such as perovskite, spinel and garnet, among several others. They also can stack single complex oxide materials and semiconductors.
“This opens up the possibility for the study of new science, which has never been possible in the past because we could not grow it,” says Eom. “Stacking these was impossible, but now it is possible to imagine infinite combinations of materials. Now we can put them together.”
In the future, robots could take blood samples, benefiting patients and healthcare workers alike.
A Rutgers-led team has created a blood-sampling robot that performed as well or better than people, according to the first human clinical trial of an automated blood drawing and testing device.
The device provides quick results and would allow healthcare professionals to spend more time treating patients in hospitals and other settings.
The results, published in the journal Technology, were comparable to or exceeded clinical standards, with an overall success rate of 87% for the 31 participants whose blood was drawn. For the 25 people whose veins were easy to access, the success rate was 97%.
The device includes an ultrasound image-guided robot that draws blood from veins. A fully integrated device, which includes a module that handles samples and a centrifuge-based blood analyzer, could be used at bedsides and in ambulances, emergency rooms, clinics, doctors’ offices and hospitals.
Venipuncture, which involves inserting a needle into a vein to get a blood sample or perform IV therapy, is the world’s most common clinical procedure, with more than 1.4 billion performed daily in the United States. But clinicians fail in 27% of patients without visible veins, 40% of patients without palpable veins and 60% of emaciated patients, according to previous studies.
Repeated failures to start an IV line boost the likelihood of phlebitis, thrombosis and infections, and may require targeting large veins in the body or arteries — at much greater cost and risk. As a result, venipuncture is among the leading causes of injury to patients and clinicians. Moreover, a hard time accessing veins can increase procedure time by up to an hour, requires more staff and costs more than $4 billion a year in the United States, according to estimates.
“A device like ours could help clinicians get blood samples quickly, safely and reliably, preventing unnecessary complications and pain in patients from multiple needle insertion attempts,” said lead author Josh Leipheimer, a biomedical engineering doctoral student in the Yarmush lab in the biomedical engineering department in the School of Engineering at Rutgers University-New Brunswick.
In the future, the device could be used in such procedures as IV catheterization, central venous access, dialysis and placing arterial lines. Next steps include refining the device to improve success rates in patients with difficult veins to access. Data from this study will be used to enhance artificial intelligence in the robot to improve its performance.
Rutgers co-authors include Max L. Balter and Alvin I. Chen, who both graduated with doctorates; Enrique J. Pantin at Rutgers Robert Wood Johnson Medical School; Professor Kristen S. Labazzo; and principal investigator Martin L. Yarmush, the Paul and Mary Monroe Endowed Chair and Distinguished Professor in the Department of Biomedical Engineering. A researcher at Icahn School of Medicine at Mount Sinai Hospital also contributed to the study.
- Josh M. Leipheimer, Max L. Balter, Alvin I. Chen, Enrique J. Pantin, Alexander E. Davidovich, Kristen S. Labazzo, Martin L. Yarmush. First-in-human evaluation of a hand-held automated venipuncture device for rapid venous blood draws. TECHNOLOGY, 2020; 1 DOI: 10.1142/S2339547819500067
“Improving our understanding of the catalyst-intermediary-reaction relationship could greatly expand the possibilities of catalytic reactions,” said Harold Kung, Walter P. Murphy Professor of Chemical and Biological Engineering at the McCormick School of Engineering, who led the research. “By learning that a chemical reaction can proceed without direct contact with a catalyst, we open the door to using catalysts from earth-abundant elements to perform reactions they normally wouldn’t catalyze.”
The study, titled “Noncontact Catalysis: Initiation of Selective Ethylbenzene Oxidation by Au Cluster-Facilitated Cyclooctene Epoxidation,” was published January 31 in the journal Science Advances. Mayfair Kung, a research associate professor of chemical and biological engineering, was a co-corresponding author on the paper. Linda Broadbelt, Sarah Rebecca Roland Professor of Chemical and Biological Engineering and associate dean for research, also contributed to the study.
The research builds on previous work in which the team investigated the selective oxidation of cyclooctene—a type of hydrocarbon—using gold (Au) as a catalyst. The study revealed that the reaction was catalyzed by dissolved gold nanoclusters. Surprised, the researchers set out to investigate how well the gold clusters could catalyze selective oxidation of other hydrocarbons.
Using a platform they developed called Noncontact Catalysis System (NCCS), the researchers tested the effectiveness of a gold catalyst against ethylbenzene, an organic compound prevalent in the production of many plastics. While ethylbenzene did not undergo any reaction in the presence of the gold clusters, the team found that when the gold clusters reacted with the cyclooctene, the resulting molecule provided the necessary intermediary to produce ethylbenzene oxidation.
The discovery opens up a range of possibilities for the design and engineering of new nanoscale devices in sensing, defence and energy storage but also shows the challenges that lie ahead for future nanotechnologies, the researchers say.
Carbon-based nanomaterials, such as diamond, were of particular scientific and technological interest because, “in their natural form, their mechanical properties could be very different from those at the micro and nanoscale,” said the lead author of the study, published in Advanced Materials, PhD student Blake Regan from the University of Technology Sydney (UTS).
“Diamond is the frontrunner for emerging applications in nanophotonics, microelectrical mechanical systems and radiation shielding. This means a diverse range of applications in medical imaging, temperature sensing and quantum information processing and communication.
“It also means we need to know how these materials behave at the nanoscale — how they bend, deform, change state, crack. And we haven’t had this information for single-crystal diamond,” Regan said.
The team, which included scientists from Curtin University and Sydney University, worked with diamond nanoneedles, approximately 20nm in length, or 10,000 times smaller than a human hair. The nanoparticles were subjected to an electric field force from a scanning electron microscope. By using this unique, non-destructive and reversible technique, the researchers were able to demonstrate that the nanoneedles, also known as diamond nanopillars, could be bent in the middle to 90 degrees without fracturing.
As well as this elastic deformation, the researchers observed a new form of plastic deformation when the nanopillar dimensions and crystallographic orientation of the diamond occurred together in a particular way.
Chief Investigator UTS Professor Igor Aharonovich said the result was the unexpected emergence of a new state of carbon (termed 08-carbon) and demonstrated the “unprecedented mechanical behaviour of diamond.”
“These are very important insights into the dynamics of how nanostructured materials distort and bend and how altering the parameters of a nanostructure can alter any of its physical properties from mechanical to magnetic to optical. Unlike many other hypothetical phases of carbon, 08-carbon appears spontaneously under strain with the diamond-like bonds progressively breaking in a zipper-like manner, transforming a large region from diamond into 08-carbon.
“The potential applications of nanotechnology are quite diverse. Our findings will support the design and engineering of new devices in applications such as super-capacitors or optical filters or even air filtration,” he said.