Scientists create sensor for night vision contact lenses

It may seem like the stuff from spy and superhero movies but scientists have created “the first room-temperature light detector that can sense the full infrared spectrum” which, according to researchers at the University of Michigan, can be made so thin that it can be easily stacked on night vision contact lenses.

Back in 2011 some speculated that Seal Team Six used night vision contact lenses in the operation that killed Osama Bin Laden. Those rumors were never substantiated, but this invention is very real…

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Graphene is like Mr. Fantastic: scientific, bendy, and out to save the world.

6 Substances That Wipe Their Ass With the Laws of Physics

#6. Graphene Can Do Almost Anything

It transports electrons 10 times faster than silicon, and may soon be replacing it as the go-to material for transistors and computer parts. …

We’re talking about “charging iPhones within five seconds” conductivity here. Imagine a world with electric cars that recharge as quickly as filling your tank with gas, or paper-thin foldable plastic phones that recharge the instant you set them down — that’s exactly what graphene offers. And then there’s the slight matter of its strength. Mix graphene with metals, and it increases their resilience 500-fold.

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Graphene-Based Artificial Retina Sensor Being Developed

Researchers at Germany’s Technical University of Munich are developing graphene sensors like the ones depicted above to serve as artificial retinas. The atom-thick sheet of linked carbon atoms is being used because it is thin, flexible, stronger than steel, transparent and electrically conductive. 

TUM physicists think that all of these characteristics and graphene’s compatibility with the body make it a strong contender to serve as the interface between a retinal prosthetic that converts light to electric impulses and the optic nerve. A graphene-based sensor could help blind people with healthy nerve tissue see, they say.

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Graphene - the new wonder material

The molecule is priceless but it is not a matter of cost – a few hundred dollars per kilo. The value lies in its potential. The molecule in question is called graphene and the EU is prepared to devote €1bn ($1.3bn) to it between 2013 and 2023 to find out if it can transform a range of sectors such as electronics, energy, health and construction. According to Scopus, the bibliographic database, more than 8,000 papers have been written about graphene since 2005.

As its name indicates, graphene is extracted from graphite, the material used in pencils. Like graphite, graphene is entirely composed of carbon atoms and 1mm of graphite contains some 3 million layers of graphene. Whereas graphite is a three-dimensional crystalline arrangement, graphene is a two-dimensional crystal only an atom thick. The carbons are perfectly distributed in a hexagonal honeycomb formation only 0.3 nanometres thick, with just 0.1 nanometres between each atom.

This 100% pure carbon simplicity confers some remarkable properties on graphene, very close to the calculated theoretical ones, as observed by the authors of A Roadmap for Graphene published in Nature last year.

Graphene conducts electricity better than copper. It is 200 times stronger than steel but six times lighter. It is almost perfectly transparent since it only absorbs 2% of light. It impermeable to gases, even those as light as hydrogen or helium, and, if that were not enough, chemical components can be added to its surface to alter its properties.

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Supercomputer Says Material Could Filter Water 100 Times Faster

Graphene’s potential to make saltwater drinkable might just match the hype the supermaterial has been garnering, researchers say.

The material, which is composed of linked carbon atoms that look like chicken-wire fencing, forms sheets so thin they are considered two-dimensional.

Researchers in many disciplines have been investigating it because it is extremely tough, offers tunable electromagnetic properties and doesn’t decompose in water, among others. When punched with precise nanoscopic holes, it is so thin that it quickly lets water molecules through while blocking things like salt ions. 

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seven-elements said:

What is the actual process of making graphene from graphite? I understand the structure and its properties, but how do they make it just one atom thick?

Graphene, for anyone who’s unaware, is pure carbon in the form of a thin, one atom thick layer. It’s very lightweight, but remarkably strong, and also conducts heat and electricity very well. As such, it’s been touted as a ‘miracle material’, for its potential use in electronic devices and many other applications - its discoverers were awarded the Nobel Prize in Physics.

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The challenge with graphene is producing large quantities of it, at a high quality, but also a low cost. Several methods are currently used, but research is still continuing in the area.

One of the first methods was a rudimentary one - the original discoverers at Manchester University used scotch tape to peel layers of carbon atoms off of graphite (an allotrope (form) of carbon). Further layers can be peeled off from these layers using the same method, until a single layer is left. This layer can then be transferred onto a silicon wafer. The issues with this method are obviously that it’s quite time-consuming, and doesn’t create a great deal of the material.

Another method is the use of Chemical Vapour Deposition (CVD), which can produce higher quality graphene. This involves carbon atoms in the gas phase being deposited onto a substrate surface, to create a thin film of graphite. This method has the issue that the graphene can subsequently be hard to remove from the substrate.

More recently, scientists in Dublin have pioneered a new method for creating graphene, using a technique called ‘shear mixing’. This involved placing it into a laboratory mixer, with a surfactant liquid, which sheared off layers of graphene when turned on. They replicated their experiment using a kitchen mixer and washing up liquid as a substitute - as a result of this, you might have spotted it in the news, with a variety of news outlets loudly urging you to ‘MAKE GRAPHENE IN YOUR KITCHEN!!”. Sadly, the exact mix of graphite and surfactant required needs to be precisely determined, using expensive analytical equipment, and not all of the graphite is converted into graphene, so separation needs to be carried out afterwards. Still, their method allowed them to produce 5 grams of graphene per hour on a very small scale - so scaled up it could be the best method yet for producing large amounts of the substance.

References & Further Reading

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Graphene: The Next Big (But Thin) Thing

If you haven’t heard of it before, you have now. And it may prove to be the next big thing in materials science. SciShow explains what it is, why it’s so awesome, and what challenges we face in harnessing its amazing properties.

Physicists show unlimited heat conduction in graphene

Scientists at the Max Planck Institute for Polymer Research (MPI-P) in Mainz and the National University of Singapore have attested that the thermal conductivity of graphene diverges with the size of the samples. This discovery challenges the fundamental laws of heat conduction for extended materials.

Davide Donadio, head of a Max Planck Research Group at the MPI-P, and his partner from Singapore were able to predict this phenomenon with computer simulations and to verify it in experiments. Their research and their results have now been presented in the scientific journal Nature Communications.

"We recognized mechanisms of heat transfer that actually contradict Fourier’s law in the micrometer scale. Now all the previous experimental measurements of the thermal conductivity of graphene need to be reinterpreted. The very concept of thermal conductivity as an intrinsic property does not hold for graphene, at least for patches as large as several micrometers", says Davide Donadio.

The French physicist Joseph Fourier had postulated the laws of heat propagation in solids. Accordingly, thermal conductivity is an intrinsic material property that is normally independent of size or shape. In graphene, a two-dimensional layer of carbon atoms, it is not the case, as our scientists now found out. With experiments and computer simulations, they found that the thermal conductivity logarithmically increases as a function of the size of the graphene samples: i.e., the longer the graphene patches, the more heat can be transferred per length unit.

This is another unique property of this highly praised wonder material that is graphene: it is chemically very stable, flexible, a hundred times more tear-resistant than steel and at the same time very light. Graphene was already known to be an excellent heat conductor: The novelty here is that its thermal conductivity, which was so far regarded as a material constant, varies as the length of graphene increases. After analyzing the simulations, Davide Donadio found that this feature stems from the combination of reduced dimensionality and stiff chemical bonding, which make thermal vibration propagate with minimal dissipation at non-equilibrium conditions.

In the micro- and nano-electronics, heat is the limiting factor for smaller and more efficient components. Therefore, materials with virtually unlimited thermal conductivity hold an enormous potential for this kind of applications. Materials with outstanding electronic properties that are self-cooling too, as graphene might be, are the dream of every electronics engineer.

Davide Donadio, an Italian-born researcher, already dealt with nanostructures of carbon, crystallization processes and thermoelectric materials during his studies in Milan, his research stays at the ETH Zurich (Switzerland) and at the University of California, Davis (USA). Since 2010, he has been investigating, among others, thermal transport in nanostructures using theoretical physics and simulating the atomic behavior of substances with his Max Planck Research Group at the MPI-P.

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Physicists Change Crystal Structure of Graphene

A Univ. of Arizona-led team of physicists has discovered how to change the crystal structure of graphene with an electric field, an important step toward the possible use of graphene in microprocessors that would be smaller and faster than current, silicon-based technology.

Graphene consists of extremely thin sheets of graphite: when writing with a pencil, graphene sheets slough off the pencil’s graphite core and stick to the page. If placed under a high-powered electron microscope, graphene reveals its sheet-like structure of cross-linked carbon atoms, resembling chicken wire. When manipulated by an electric field, parts of the material are transformed from behaving as a metal to behaving as a semiconductor, the UA physicists found.

Read more: http://www.laboratoryequipment.com/news/2014/05/physicists-change-crystal-structure-graphene

You too can make Nobel Prize winning, super-material Graphene!

Here is how:

First, pour some graphite powder into a blender. Add water and dishwashing liquid, and mix at high speed. Congratulations, you just made the wonder material graphene.

This surprisingly simple recipe is now the easiest way to mass-produce pure graphene – sheets of carbon just one atom thick. 

If you need a reminder on graphene and its super powers then read up on it here.

Columbia researchers recently published work using quantum mechanics and a supercomputer to reveal how the world’s strongest, thinnest materials break. The study was inspired by previous work on graphene and found that several other monolayer materials have a very similar failure mechanism despite having extremely different electronic properties.

Their results contradict previous explanations of why graphene breaks based on a well-known concept in physics called a “Peierls instability”.

Image: Top and side orthographic projections of the distorted structures for (a) graphene, (b) BN, (c) graphane, and (d) MoS2 at equibiaxial strains of 0.212, 0.240, 0.328, and 0.270, respectively. The C, B, N, H, Mo, and S atoms are represented as brown, green, silver, white, purple, and yellow spheres, respectively. Dashed lines indicate the undistorted strained lattice.

Graphene-based solar cell hits record 15.6 percent efficiency

In 2012, researchers from the University of Florida reported a record efficiency of 8.6 percent for a prototype solar cell consisting of a wafer of silicon coated with a layer of graphene doped with trifluoromethanesulfonyl-amide (TFSA). Now another team is claiming a new record efficiency of 15.6 percent for a graphene-based solar cell by ditching the silicon all together. The prototype photovoltaic device, created by researchers from the Group of Photovoltaic and Optoelectronic Devices (DFO) at Spain’s Universitat Jaume I in Castelló and Oxford University, uses a combination of titanium oxide and graphene as a charge collector and perovskite as a sunlight absorber. As well as the impressive solar efficiency, the team says the device is manufactured at low temperatures, with the several layers that go into making it being processed at under 150° C (302° F) using a solution-based disposition technique. This not only means lower potential production costs, but also makes it possible for the technology to be used on flexible plastics. The team’s paper is published in the journal Nano Letters. (via Graphene-based solar cell hits record 15.6 percent efficiency)

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