Electronics - Page 14

Researchers from Tomsk Polytechnic University, along with additional international colleagues, have discovered a method to modify and use graphene without destroying it. Thanks to the method, the researchers were able to synthesize a well-structured polymer with a strong covalent bond on single-layer graphene.

The researchers call the result "polymer carpets". The structure is highly stable and less prone to degradation over time, holding promise for the development of flexible organic electronics. If a layer of molybdenum disulfide is added over this "nanocarpet," the resulting structure generates current under exposure to light.

As part of a national research collaboration, Spanish researchers including the ICN2 have reached a milestone in graphene research, that potentially brings science a step closer to using graphene in filtration and sensing applications.

The researchers have successfully synthesized a graphene membrane with pores whose size, shape and density can be tuned with atomic precision at the nanoscale. Engineering pores at the nanoscale in graphene can change its fundamental properties. It becomes permeable or sieve-like, and this change alone, combined with graphene's intrinsic strength and small dimensions, points to its future use as the most resilient, energy-efficient and selective filter for extremely small substances including greenhouse gases, salts and biomolecules.

Researchers at MIT and Harvard University have found that graphene can be tuned to behave at two electrical extremes: as an insulator, in which electrons are completely blocked from flowing; and as a superconductor, in which electrical current can stream through without resistance.

Researchers in the past, including this team, have been able to synthesize graphene superconductors by placing the material in contact with other superconducting metals — an arrangement that allows graphene to inherit some superconducting behaviors. In this new work, the team found a way to make graphene superconduct on its own, demonstrating that superconductivity can be an intrinsic quality in the purely carbon-based material.

A collaboration between Spanish research institutes—led by the nanoGUNE Cooperative Research Center (CIC)—has achieved a breakthrough in so-called molecular electronics by devising a way to connect magnetic porphyrin molecules to graphene nanoribbons. These connections may be an example of how graphene could enable the potential of molecular electronics.

Porphyrin is an important molecule that is responsible for making photosynthesis possible in plants and transporting oxygen in the blood. Recently, researchers have been experimenting with "magnetic porphyrins" and discovered that they can form the basis of spintronic devices. Spintronics involves manipulating the spin of electrons and it is this spin that is responsible for magnetism: When a majority of electrons in a material have their spins pointing in the same direction, the material is magnetized. If you can move all the spins up or down and can read that direction, you can create the foundation of the 0 and 1 of digital logic.

A team of Chinese scientists has developed graphene-based high temperature-resistant memristors, which are leading candidates for future storage and neuromorphic computing, with potential to address existing challenges in the development of electronic devices.

The sandwich-like memristor is composed of two layers of graphene, with a layer of molybdenum disulfide in the middle. The memristor devices exhibit excellent thermal stability and can operate at a high temperature of up to 340 degrees Celsius.

Researchers from Cornell University and Honeywell Aerospace have designed a graphene-enhanced transient electronics technology in which the microchip self-destructs by vaporizing an action that can be remotely triggered without releasing harmful byproducts. In addition to transient electronics, the technology might find application in environmental sensors that can be remotely vaporized once they're no longer needed.

A silicon-dioxide microchip is attached to a polycarbonate shell. Microscopic cavities within the shell contain rubidium and sodium bifluoride. When triggered remotely by using radio waves, these chemicals thermally react and decompose the microchip. The radio waves open graphene-on-nitride valves that keep the chemicals sealed in the cavities, allowing the rubidium to oxidize, release heat and vaporize the polycarbonate shell. The sodium bifluoride releases hydrofluoric acid to etch away the electronics.

Researchers at Iowa State University, along with collaborators at Rice University, Ames Laboratory and Lehigh University, have designed a new graphene printing technology that can produce electronic circuits that are low-cost, flexible, highly conductive and water repellent. The scientists explain that this technology could enable self-cleaning wearable/washable electronics that are resistant to stains, or ice and biofilm formation.

We’re taking low-cost, inkjet-printed graphene and tuning it with a laser to make functional materials, said authors of the paper. The work describes how the team used inkjet printing technology to create electric circuits on flexible materials. In this case, the ink is flakes of graphene. The printed flakes, however, aren’t highly conductive and have to be processed to remove non-conductive binders and weld the flakes together, boosting conductivity and making them useful for electronics or sensors. Such post-print processes typically involve heat or chemicals, but the research group developed a rapid-pulse laser process that treats the graphene without damaging the printing surface even if it’s paper.

Researchers from the Pierre Aigrain Laboratory in the ENS Physics department in Paris, France, have discovered a new cooling mechanism for electronic components made of graphene deposited on boron nitride. The efficiency of this mechanism reportedly allowed the team to reach electric intensities at the intrinsic limit of the laws of conduction.

Current-voltage (left) and temperature-voltage (right) characteristics of a graphene on boron nitride transistor. The transistor effect is visible by modulation of the current as a function of the gate voltage in the Zener-Klein tunnel transport regime.

Heat dissipation is vital in order to prevent deterioration or destruction of electronic components. The laws of physics dictate that increasing the density of components on a chipset implies increasing dissipation and thus heat. Nowadays, with the advances in 2D material devices, this question becomes particularly critical since components are required to be one atom thick. By producing a graphene-based transistor deposited on a boron nitride substrate, the team demonstrated a new cooling mechanism 10 times more efficient than basic heat diffusion. This new mechanism, which exploits the two-dimensional nature of the materials opens a "thermal bridge" between the graphene sheet and the substrate.

Researchers from Cornell have developed tiny graphene-enhanced robot exoskeletons that can rapidly change shape upon sensing chemical or thermal changes in its environment. And, they claim, these microscale machines equipped with electronic, photonic and chemical payloads could become a powerful platform for robotics at the size scale of biological microorganisms.

We are trying to build what you might call an ‘exoskeleton’ for electronics, said the team. Right now, you can make little computer chips that do a lot of information-processing … but they don’t know how to move or cause something to bend.

Scientists at The University of Manchester have reported the development of a simple and cost-effective method to manufacture graphene-based wearable electronic textiles on an industrial scale. The new method could allow graphene e-textiles to be manufactured at commercial production rates of 150 meters per minute, the team said. Our simple and cost-effective way of producing multi-functional graphene textiles could easily be scaled up for many real-life applications, such as sportswear, military gear, and medical clothing, said the researchers.

The team reversed the previous process of coating textiles with graphene-based materials; Traditionally, the textiles are first coated with graphene oxide, which is then converted into its functional form of reduced graphene oxide. Instead, the researchers first reduced the graphene oxide in solution, and then coated the textiles with the reduced form.