Tag Archives: graphene
he tiniest microchips yet can be made from graphene and other 2D-materials, using a form of ‘nano-origami’, physicists at the University of Sussex have found. This is the first time any researchers have done this, and it is covered in a paper published in the ACS Nano journal.
By creating kinks in the structure of graphene, researchers at the University of Sussex have made the nanomaterial behave like a transistor, and have shown that when a strip of graphene is crinkled in this way, it can behave like a microchip, which is around 100 times smaller than conventional microchips.
The base of the 2D-material with the white lines showing the structural kinks which modify the electrical properties mechanically.
“Using these nanomaterials will make our computer chips smaller and faster. It is absolutely critical that this happens as computer manufacturers are now at the limit of what they can do with traditional semiconducting technology. Ultimately, this will make our computers and phones thousands of times faster in the future.
“This kind of technology – “straintronics” using nanomaterials as opposed to electronics – allows space for more chips inside any device. Everything we want to do with computers – to speed them up – can be done by crinkling graphene like this.”
Dr Manoj Tripathi, Research Fellow in Nano-structured Materials at the University of Sussex and lead author on the paper, explained: “Instead of having to add foreign materials into a device, we’ve shown we can create structures from graphene and other 2D materials simply by adding deliberate kinks into the structure. By making this sort of corrugation we can create a smart electronic component, like a transistor, or a logic gate.”
As the COVID-19 pandemic continues to spread across the world, testing remains a key strategy for tracking and containing the virus. Bioengineering graduate student, Maha Alafeef, has co-developed a rapid, ultrasensitive test using a paper-based electrochemical sensor that can detect the presence of the virus in less than five minutes. The team led by professor Dipanjan Pan reported their findings in ACS Nano.
“Currently, we are experiencing a once-in-a-century life-changing event,” said Alafeef. “We are responding to this global need from a holistic approach by developing multidisciplinary tools for early detection and diagnosis and treatment for SARS-CoV-2.”
There are two broad categories of COVID-19 tests on the market. The first category uses reverse transcriptase real-time polymerase chain reaction (RT-PCR) and nucleic acid hybridization strategies to identify viral RNA. Current FDA-approved diagnostic tests use this technique. Some drawbacks include the amount of time it takes to complete the test, the need for specialized personnel and the availability of equipment and reagents. The second category of tests focuses on the detection of antibodies. However, there could be a delay of a few days to a few weeks after a person has been exposed to the virus for them to produce detectable antibodies.
n recent years, researchers have had some success with creating point-of-care biosensors using 2D nanomaterials such as graphene to detect diseases. The main advantages of graphene-based biosensors are their sensitivity, low cost of production and rapid detection turnaround. “The discovery of graphene opened up a new era of sensor development due to its properties. Graphene exhibits unique mechanical and electrochemical properties that make it ideal for the development of sensitive electrochemical sensors,” said Alafeef. The team created a graphene-based electrochemical biosensor with an electrical read-out setup to selectively detect the presence of SARS-CoV-2 genetic material.
There are two components to this biosensor: a platform to measure an electrical read-out and probes to detect the presence of viral RNA. To create the platform, researchers first coated filter paper with a layer of graphene nanoplatelets to create a conductive film. Then, they placed a gold electrode with a predefined design on top of the graphene as a contact pad for electrical readout. Both gold and graphene have high sensitivity and conductivity which makes this platform ultrasensitive to detect changes in electrical signals.
In 1959, former Cornell physicist Richard Feynman delivered his famous lecture “There’s Plenty of Room at the Bottom,” in which he described the opportunity for shrinking technology, from machines to computer chips, to incredibly small sizes. Well, the bottom just got more crowded. A Cornell-led collaboration has created the first microscopic robots that incorporate semiconductor components, allowing them to be controlled – and made to walk – with standard electronic signals. These robots, roughly the size of paramecium, provide a template for building even more complex versions that utilize silicon-based intelligence, can be mass produced, and may someday travel through human tissue and blood.
The collaboration is led by Itai Cohen, professor of physics, Paul McEuen, the John A. Newman Professor of Physical Science – both in the College of Arts and Sciences – and their former postdoctoral researcher Marc Miskin, who is now an assistant professor at the University of Pennsylvania.
The walking robots are the latest iteration, and in many ways an evolution, of Cohen and McEuen’s previous nanoscale creations, from microscopic sensors to graphene-based origami machines. The new robots are about 5 microns thick (a micron is one-millionth of a meter), 40 microns wide and range from 40 to 70 microns in length. Each bot consists of a simple circuit made from silicon photovoltaics – which essentially functions as the torso and brain – and four electrochemical actuators that function as legs. As basic as the tiny machines may seem, creating the legs was an enormous feat.
“In the context of the robot’s brains, there’s a sense in which we’re just taking existing semiconductor technology and making it small and releasable,” said McEuen, who co-chairs the Nanoscale Science and Microsystems Engineering (NEXT Nano) Task Force, part of the provost’s Radical Collaboration initiative, and directs the Kavli Institute at Cornell for Nanoscale Science.
“But the legs did not exist before,” McEuen said. “There were no small, electrically activatable actuators that you could use. So we had to invent those and then combine them with the electronics.”
The team’s paper, “Electronically Integrated, Mass-Manufactured, Microscopic Robots,” has been published in Nature.
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.
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 which 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 graphene layers integrated onto textiles.
The new research published today in journal Nano Letters, demonstrates that the smart optical textile technology can change its thermal visibility.
“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”, explained Professor Coskun Kocabas, who led the research.
“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“, he added.
When Andre Geim and Kostya Novoselov first isolated graphene in 2004, it opened the door for a wave of innovation based on the wonder material’s jaw-dropping properties. Until now, however, it’s fair to say the Nobel-winning discovery has had limited impact for the average consumer. But that could all be about to change.
Wearable electronics, sports equipment and smartphones have all hitched their wagons to the graphene hype train in recent times, playing on the material’s incredible strength and conductivity. In many cases, its inclusion is probably more beneficial to marketing departments than actual end users, although we’re also finally seeing some products that are genuinely tapping into graphene’s enormous potential.
Canadian startup Ora’s GrapheneQ™ (GQ) headphones fall squarely into the latter category. GrapheneQ is the company’s proprietary composite material, used to make the 40mm acoustic drivers that actually deliver sound to the ear. Consisting of more than 95 per cent graphene, it retains most of the material’s mechanical properties, while at the same time being easier to shape and less expensive to produce. Rather than recreating graphene’s single layer of carbon atoms, GQ consists of flakes of graphene deposited in thousands of layers bonded together with proprietary cross-linking agents. It is lightweight and stiff, with a low density, making it an ideal material for loudspeaker membranes.
“Without a doubt, the most exciting aspect about the technology is the unique mechanical properties it holds,” says Ari Pinkas, Ora’s co-founder and business lead. “It is very uncommon for such a rigid material to be so lightweight. This rare combination of high stiffness and low density allows for some pretty cool things in the audio world. To start with, acoustic transducers are already notoriously inefficient: less than 10 per cent of the energy that goes into a loudspeaker gets translated to sound, over 90 per cent simply turns into unwanted heat.”
Having an ultra-lightweight speaker membrane results in a considerable power saving, something that’s particularly desirable for wireless consumer electronics such as smartphones, portable speakers and Bluetooth headphones.
“The fact that GrapheneQ is so lightweight means that it takes considerably less energy to move than other materials,” said Pinkas. “More concretely, Ora has observed up to a 70 per cent extension in the battery life of an audio dedicated device when doing physical A/B comparison measurements replacing a loudspeaker’s original membrane with a GrapheneQ cone.”
A Rutgers-led team has created better biosensor technology that may help lead to safe stem cell therapies for treating Alzheimer’s and Parkinson’s diseases and other neurological disorders.
The technology, which features a unique graphene and gold-based platform and high-tech imaging, monitors the fate of stem cells by detecting genetic material (RNA) involved in turning such cells into brain cells (neurons), according to a study in the journal Nano Letters.
Stem cells can become many different types of cells. As a result, stem cell therapy shows promise for regenerative treatment of neurological disorders such as Alzheimer’s, Parkinson’s, stroke and spinal cord injury, with diseased cells needing replacement or repair. But characterizing stem cells and controlling their fate must be resolved before they could be used in treatments. The formation of tumors and uncontrolled transformation of stem cells remain key barriers.
This unique biosensing platform consists of an array of ultrathin graphene layers and gold nanostructures. The platform, combined with high-tech imaging (Raman spectroscopy), detects genetic material (RNA) and characterizes different kinds of stem cells with greater reliability, selectivity and sensitivity than today’s biosensors.
“A critical challenge is ensuring high sensitivity and accuracy in detecting biomarkers – indicators such as modified genes or proteins – within the complex stem cell microenvironment,” said senior author KiBum Lee, a professor in the Department of Chemistry and Chemical Biology in the School of Arts and Sciences at Rutgers University–New Brunswick. “Our technology, which took four years to develop, has demonstrated great potential for analyzing a variety of interactions in stem cells.”
The United States is seeing an increase in the number of neurological diseases. Stroke is ranked as the fifth leading cause of death, with Alzheimer’s being ranked sixth. Another neurological disease – Parkinson’s – affects nearly 1 million people in the U.S. each year. Implantable neurostimulation devices are a common way to treat some of these diseases. One of the most commonly used elements in these devices is platinum microelectrodes – but it is prone to corrosion, which can reduce the functional lifetime of the devices. Purdue University researchers have come up with a solution to help – they are adding a graphene monolayer to the devices to protect the microelectrodes.
“I know from my industry experience that the reliability of implantable devices is a critical issue for translating technology into clinics,” said Hyowon “Hugh” Lee, an assistant professor in Purdue’s College of Engineering and a researcher at the Birck Nanotechnology Center, who led the research team. “This is part of our research focusing on augmenting and improving implantable devices using nano and microscale technologies for more reliable and advanced treatments. We are the first ones that I know of to address the platinum corrosion issue in neurostimulation microelectrodes.”
Lee said he learned about the advantage of using graphene from his colleague at Birck Nanotechnology Center, Zhihong Chen, who is an expert in graphene technology. The team has shown the graphene monolayer to be an effective diffusion barrier and electrical conductor.
“If you attempt to deliver more charge than the electrode can handle, it can corrode the electrode and damage the surrounding tissues,” Lee said. He also thinks that microscale electrodes are going to play a key role in the future with more demand for precise and targeted neurostimulation therapy. “We think neurosurgeons, neurologists, and other scientists in neuroengineering field will be able to use this electrode technology to better help patients with implantable devices for restoring eyesight, movement, and other lost functionalities.”
Lee and his team are working with the Purdue Research Foundation Office of Technology Commercialization on patenting and licensing the technology. They are looking for partners interested in licensing it.
The research has been published in the journal 2D Materials.
Wearable devices that harvest energy from movement are not a new idea, but a material created at Rice University may make them more practical. The Rice lab of chemist James Tour has adapted laser-induced graphene (LIG) into small, metal-free devices that generate electricity. Like rubbing a balloon on hair, putting LIG composites in contact with other surfaces produces static electricity that can be used to power devices. For that, thank the triboelectric effect, by which materials gather a charge through contact. When they are put together and then pulled apart, surface charges build up that can be m.
In experiments, the researchers connected a folded strip of LIG to a string of light-emitting diodes and found that tapping the strip produced enough energy to make them flash. A larger piece of LIG embedded within a flip-flop let a wearer generate energy with every step, as the graphene composite’s repeated contact with skin produced a current to charge a small capacitor.
An electron microscope image shows a cross-section of a laser-induced graphene and polyimide composite created at Rice University for use as a triboelectric nanogenerator. The devices are able to turn movement into energy that can then be stored for later use
This could be a way to recharge small devices just by using the excess energy of heel strikes during walking, or swinging arm movements against the torso,” Tour said.
LIG is a graphene foam produced when chemicals are heated on the surface of a polymer or other material with a laser, leaving only interconnected flakes of two-dimensional carbon. The lab first made LIG on common polyimide, but extended the technique to plants, food, treated paper and wood.
The project is detailed in the American Chemical Society journal ACS Nano.
DGIST research group in South Korea developed single-layer graphene based multifunctional transparent devices Various use of electronics and skin-attachable devices are expected with the development of transparent battery that can both generate and store power.The scientists in the Smart Textile Research Group developed film-type graphene based multifunctional transparent energy devices.
The team actively used ‘single-layered graphene film’ as electrodes in order to develop transparent devices. Due to its excellent electrical conductivity and light and thin characteristics, single-layered graphene film is perfect for electronics that require batteries. By using high-molecule nano-mat that contains semisolid electrolyte, the research team succeeded in increasing transparency (maximum of 77.4%) to see landscape and letters clearly.
Furthermore, the researchers designed structure for electronic devices to be self-charging and storing by inserting energy storage panel inside the upper layer of power devices and energy conversion panel inside the lower panel. They even succeeded in manufacturing electronics with touch-sensing systems by adding a touch sensor right below the energy storage panel of the upper layer.
“We decided to start this research because we were amazed by transparent smartphones appearing in movies. While there are still long ways to go for commercialization due to high production costs, we will do our best to advance this technology further as we made this success in the transparent energy storage field that has not had any visible research performances”, explains Changsoon Choi from the Smart Textile Research Group, and co-author of the paper published on the online edition of ACS Applied Materials & Interfaces.
The findings were also conducted as a joint research with various organisations such as Yonsei University, Hanyang University, and the Korea Institute of Industrial Technology (KITECH).
A team of engineers at the UC Berkeley and the Keck Graduate Institute (KGI) of The Claremont Colleges combined CRISPR with electronic transistors made from graphene to create a new hand-held device that can detect specific genetic mutations in a matter of minutes.
The device, dubbed CRISPR-Chip, could be used to rapidly diagnose genetic diseases or to evaluate the accuracy of gene-editing techniques. The team used the device to identify genetic mutations in DNA samples from Duchenne muscular dystrophy patients.
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“We have developed the first transistor that uses CRISPR to search your genome for potential mutations,” said Kiana Aran, an assistant professor at KGI who conceived of the technology while a postdoctoral scholar in UC Berkeley bioengineering professor Irina Conboy’s lab. “You just put your purified DNA sample on the chip, allow CRISPR to do the search and the graphene transistor reports the result of this search in minutes.”
Aran, who developed this technology and brought it to fruition at KGI, is the senior author of a paper describing the device that appears online March 25 in the journal Nature Biomedical Engineering.
Doctors and geneticists can now sequence DNA to pinpoint genetic mutations underlying a host of traits and conditions, and companies like 23andMe and AncestryDNA even make these tests available to curious consumers.