Tag: graphene

Graphene could create a computer brain

mybrainhurtsFlakes of graphene might be the the key to building computer chips that can processes information similar to human brain does – not your brain of course, or mine, but a better class of brain .

The technology is centred on neuromorphic chips which are made up of networks of transistors that interact the way human neurons do. This means that they can process analog input, such as visual information, quicker and more accurately than traditional chips.

Bhavin Shastri, a postdoctoral fellow in electrical engineering at Princeton University said that one way of building such transistors is to construct them of lasers that rely on an encoding approach called “spiking.”

Depending on the input, the laser can provide a brief spike in its output of photons or not respond at all. Instead of using the on or off state of the transistor to represent the 1s and 0s of digital data, these neural transistors rely on the time intervals between spikes.

Shastri said: “We’re essentially using time as a way of encoding information. Computation is based on the spatial and temporal positions of the pulses. This is sort of the fundamental way neurons communicate with other neurons.”

Shastris work with Lawrence Chen, a professor of electrical and computer engineering at McGill University, is trying to get the laser to spike at picosecond time scales which are one trillionth of a second.

They managed to do this by putting a tiny piece of graphene inside a semiconductor laser. The graphene acts as a “saturable absorber,” soaking up photons and then emitting them in a quick burst.

Graphene is a good saturable absorber because it can take up and release a lot of photons extremely fast, and it works at any wavelength.It also stands up very well to all the energy produced inside a laser.


Super sensitive magnetic sensor invented

MagnetScientists at the National University of Singapore (NUS) said they have developed a hybrid sensor more sensitive than sensors currently available.

The scientists said that the invention will lead to the development of smaller and cheaper censors for electronics, comms, automotive and biotechnology applications.

The hybrid sensor developed by the scientists may meet the needs of high sensitivity to low and high magnetic fields, tunability and small resistance variations due to temperature.

The team claims that the sensor, which is made of graphene and boron nitride is 200 times more sensitive than commercially available sensors today.

Existing sensors are commonly made of silicon and indium antimonide, but these new sensors have an eight fold gain over previously reported laboratory results.

The magnetoresistance sensor industry is expected to be worth nearly $3 billion by the year 2020. One advantage over existing sensors is that there won’t be a need for silicon wafers or temperature corretion circuity, with production cost for graphene based sensors much lower.

Graphene nanoribbons get real

Picture courtesy of Wikimedia CommonsScientists get very excited about graphene because of its electronic properties, but so far there is little sign of anything real appearing based on the stuff.

Graphene is a sheet of carbon atoms only one atom in thickness and which is a better conductor than silicon.

But now scientists at the University of Wisconsin-Madison (UWM) say they’ve hit on a way to grow ultra narrow strips – nanoribbons – on conventional semiconductor wafers.

This, they said will let vendors build graphene nanoribbons into hybrid integrated circuits speeding up electronic devices.

Associate professor Michael Arnold believes the techinque developed by the UWM team can be scaled for mass production.

“Graphene nanoribbons that can be grown directly on the surface of a semiconductor like germanium are more compatible with planar processing that’s used in the semiconductor industry, and so there would be less of a barrier to integrating these really excellent materials into electronics in the future,” he said.

The UWM researchers grow ultra narrow nanoribbons with smooth straight edges on the wafers using chemical vapour deposition. The nanoribbons have to be less than 10 nanometres. That’s thin.

There’s yet another performance gain for Lithium ion-batteries

lemon batteryIt seems that the world+dog is coming up with new ways to double the capacity of lithium-ion batteries.

Last week, we told how MIT had come up with a cunning plan and now it seems that Samsung researchers have developed materials that double the power capacity of lithium-ion batteries.

Writing in the popular science magazine Nature, Samsung Advanced Institute of Technology (SAIT) said the technology uses silicon cathode material coded with high-crystalline graphene to produce batteries with twice as much capacity as ordinary lithium-ion batteries.

It claimed that the new technology will enhance the performance of mobile devices and electric vehicles.

Son In-hyu SAIT  researcher at said that the research has dramatically improved the capacity of lithium-ion batteries by applying a new synthesis method of high-crystalline graphene to a high-capacity silicon cathode. We will continue to improve the secondary cell technology to meet the expanding demand from mobile device and electric vehicle markets.

The lithium-ion battery was introduced in 1991 and its storage capacity has been gradually improved. But the material’s properties have limited improvements to capacity, failing to follow skyrocketing demand from the mobile and electric car industries.

SAIT said its researchers focused on graphene, a relatively new material that is physically strong and highly conductive, to solve this problem.

This material has up to four times the capacity compared with graphite and can double the energy density of ordinary lithium-ion batteries.

Patents covering the new technology have been applied for in Korea, China, Europe and the United States.

Scientists create 3D graphene shapes

GrapheneGraphene, which holds promise for future electronics devices, comes normally in flat sheets.

But scientists at the University of Illinois said they’ve been able to form 3D shapes from those flat sheets.

And that, they said, holds great promise for future graphene MEMS hybrid devices and for flexible electronics.

SungWoo Nam, an assistant professor at Illinois, said a variety of structures can be created including pyramids, pillars, domes, and 3D integration of gold nanoparticles.

“The flexibility and 3D nature of our structures will enable intimate biosensing devices which can be conformed to the shape and characteristics of human skin and other biological systems,” said Nam. “We also expect that our new 3D integration approach will facilitate advanced classes of hybrid devices beween microelectromechanical systems (MEMS) and 2D materials for sensing and actuation.”

Scientists promise to speed up chips

GrapheneScientists at Stanford School of Engineering believe they have devised a method to speed up data transport in semiconductors by as much as 30 percent in the future.

While a typical semiconductor has millions of transistors connected by tiny copper wires, it’s the sheath that has given the Stanford scientists inspiration.

They said that tantalum nitride has been used to sheath the copper wires within chips.

But experiments show that if graphene is used as a sheath, electrons can fly through the copper wires faster.

The sheath over the tiny copper wires prevents them from interacting with the silicon and also conducts electricity.

But the Stanford team shows that a graphene layer would be eight times thinner than one made from tantalum nitride. But using graphene as a layer can also act as an auxiliary conductor of electrons as well as isolating the copper from the silicon.

But while the method holds promise, there are still hurdles to adopting graphene to this purpose. That would include methods to grow graphene directly onto the wires during mass production.

Graphene spins like nothing else on earth

illustration courtesy Chalmers University of TechnologyScientists at Chalmers University of Technology said that large area graphene preserves electronic spin over a long period.

And that means the window is now open for the long-touted spintronics, promising faster CPUs and memory for computers.

The aptly named Saroj Dash, head of the research group at Chalmers, said: “These results will attract a lot of attention in the research community and put graphene on the map for applications in spintronic components.”

Spintronics, already used in state of the art hard drives but Dash believes there’s more exciting times ahead. “The thin carbon film is not only an excellent electrical conductor, but also theoretically has the rare ability to maintain the electronics with the spin intact,” said Dash.

That means that in spin components of the future, electrons will be able to travel several tens of micrometers with spins staying aligned, something you can’t do with aluminium or copper, Dash said.

The researchers have managed to create graphene through chemical vapour deposition. Dash said: “The CVD graphene can also be easily removed from the copper foil on which it grows and is lifted onto a silicon wafer. There are good prospects for the production of large area graphene on an industrial scale.”

So when, and if, will we see spintronic computers? On that subject Dash is a little more pessimistic. He said: “Whether spintronics can eventually fully replace semiconductor technology is an open question.”

Scientists working on smart contact lenses

Although Google Glass has yet to hit retail and flop, scientists are already working on next generation wearable devices and they include smart contact lenses.

One of the main problems facing Google Glass is its sheer bulk. The device is still pretty big, yet despite its size it doesn’t offer a lot of battery life. Scientists in Korea and Switzerland believe smart contact lenses, built using a new generation of nanomaterials, are the way to go.

A team led by Jang-Ung Park at the Ulsan National Institute of Science and Technology managed to mount a light emitting diode on an off the shelf contact lens. The team came up with a special material of their own to make it possible – a stretchy mix of graphene and silver nanowires, reports Technology Review

They tested their contraption on rabbits. The fluffy test subjects didn’t seem to mind, and did not rub their eyes. 

Meanwhile a Swiss team at Sensimed is working on a smart lens for 24-hour monitoring of eye pressure in glaucoma patients. Like the bunnies, they don’t seem to mind, either. University of Washington professor and Google Glass project founder Babak Parviz has also dabbled in contact-lens displays, but they were built using rigid, non-transparent materials.  

Scientists develop printable graphene ink

A team of researchers at Northwestern Engineering has come up with a new way of producing graphene, which could eventually lead to printable graphene ink.

One of the methods used to produce graphene involves exfoliating graphite through oxidation or the use of various solvents. However, the techniques tend to interfere with the conductive properties of graphene, greatly diminishing its potential. 

The Northwestern graphene team took up the challenge and eventually came up with a conductivity preserving production method that works at room temperature, which should help keep production costs down. In addition, they used cheap and readily available solvents such as ethanol and ethyl cellulose. The latter can even be used as a food additive, which means it is pretty clean and safe, reports Clean Technica

In the end they managed to produce a powder of high concentration graphene flakes and they can transform their product into a printable ink, simply by adding another solvent.

Printable graphene circuits could drastically reduce production costs, as they could use existing printers rather than develop proprietary manufacturing techniques. This means graphene-based circuits and solar cells could become very cheap, very fast. 

IBM team reveals atomic imaging breakthrough

IBM researchers have pushed the boundaries of microscopy power in a development that could assist in the future production computer chips using graphene.

For the first time, the researchers were able to detect the individual bonds that hold atoms together, using atomic force microscopy to create an image at this small scale.

The powerful microscope has, at its tip, just one carbon monoxide atom, and the IBM team has in the past been able to use it to detect the chemical structure of single atoms.  Now they have been able to determine individual bonds between atoms, measuring the force between the tip of the microscope and the sample, creating an image of the bonds, which can be just one-hundredth of an atom’s diameter.  

According to IBM, this could prove very useful in developing a future generation of electronics. The likes of Intel believe that chip production should continue relatively steadily until around the 5nm stage, so many are on the lookout for new semiconductor production methods.  

While graphene is clearly a long way from supplanting silicon in chips, with many steps to overcome to prove that it could one day work at commercial levels in the same way that silicon has succeeded, IBM and others such as Samsung are investing in lab developments.

IBM says that the ability to image bonds at the this level could assist in graphene development, a material which consists of atom thick layers of carbon placed on top of each other to often astounding effect.