Showing posts with label Nanotubes. Show all posts

Written by fatih al-farahat in


Graphene Sensing Tool



The graphene news just keeps getting better and more exciting. Read through this. A little bit of neat fabrication has given us a device able to measure the weight of a couple of atoms.


Thus we are already making up neat tools with this stuff. The real point here is that complex geometric shapes can be contemplated and ultimately fabricated if justified.


We have already outlined some of the developing aspects of this extraordinary technology. I am still getting over the fact that we can fly continuous nanotubes off a tool to creditably produce the space cable that Arthur C. Clark dreamt of


Can you imagine a battle armor woven with this stuff? The advantage to the armor would surely match that of the original plate of the high middle ages. Likely it can reach the level that the contents would be vaporized before penetration becomes an issue. It would also be very light and obviously impervious to wear.


This is surely the most important materials discovery made ever. As we become more adept at producing it and working with it, we can expect it to possibly displace most other materials including metals. The main factor will be cost, but this promises to get cheap fast.


Particularly when the labs have been producing it for their work by the expedient of applying scotch tape to a chunk of graphite, which is quite enough to make you chuckle.



Graphene works as a highly sensitive mass detector


Sep 29, 2009


http://physicsworld.com/cws/article/news/40552


http://images.iop.org/objects/physicsweb/news/13/9/32/graphene1.jpg


Researchers at Columbia University in New York have made the first electrical-readout nanomechanical resonators made from graphene. The devices, which consist of vibrating sheets of graphene suspended over micron-sized trenches, could be used as highly sensitive, robust, mass detectors.


Graphene sheets are sheets of carbon that are just one atom thick. As well as having remarkable electronic properties, graphene is extremely stiff and strong. This means that the material can be made into bridge-like resonators that vibrate at very high frequencies. Because such a resonator has an extremely small mass, its resonant frequency changes each time a molecule is adsorbed onto its surface.


"Although graphene shares these advantages with carbon nanotubes, which have also been used to make highly sensitive mass detectors, it has the added bonus of being a 2D sheet that we can 'carve' into the shapes we want," explained team leader James Hone. "This gives us more control over the properties of the finished resonators."


Suspended graphene


The Columbia team made its devices by placing graphene sheets onto silicon/silica substrates, then patterning metal electrodes and etching away the silica to produce suspended graphene. The portion of each electrode that is in contact with the graphene is also suspended, which makes electrical readout easier later on.


The devices vibrate at megahertz frequencies, with a peak around 65 MHz that depends on the device geometry. The frequency can also be adjusted with a DC voltage applied to the gate, which introduces tension to the sheet. When an object is placed on the device, the frequency changes – and the change is detected with the electrodes, and used to calculate the mass of the molecule.


Sensitive to two gold atoms


"Our measurements indicate that the devices should be sensitive to around 1 zeptogram (10–21g), which is about two gold atoms, at low temperatures" Hone told our sister website nanotechweb. "They also show that the response is not as simple as expected because placing material on the graphene changes both the mass of the sheet and its tension – a new phenomenon that has never been seen before."


The team is now experimenting with different geometries for the devices and looking at various readout techniques that will improve their performance.


The work was published in Nature Nanotechnology.


About the author


Belle Dumé is a contributing editor to nanotechweb.


Written by fatih al-farahat in , ,


Billion Year Memories

I suppose that this will go largely unnoticed but this is very welcome news. Here we have a bullet proof method of storing data that is for all intents and purposes eternal.

I have always been conscious of how much we have lost of mankind’s creative output.

I am also conscious of how much we are now digitalizing onto media that is still physically transient. Have you checked the content of those 3 ½ discs lately? Do not wait if you think any of it may be important. Now we are getting technology that provides permanent storage that should satisfy every librarian for a billion years. This was only possible in science fiction before now.

In a way, we are entering a world in which a little bit of our lives will become immortal. Scary thought, but our great grand children will be able to trace the spoor of our lives even though they never met us. I have a few scraps of my mother’s handwriting and none at all of anyone else’s. How different might it be to read their mail and parse their lives and friendships and appreciate their efforts and contributions? Surely it would be better than a disconnected fiction about strangers.

Today we are creating such personal spoor on the internet and none of it needs to be lost.

A Billion Year Ultra-Dense Memory Chip

http://www.spacemart.com/reports/A_Billion_Year_Ultra_Dense_Memory_Chip_999.html

by Staff Writers
Berkeley CA (SPX) Jun 05, 2009

Berkeley Lab researchers have created a unique ultra-high density memory storage medium that can preserve digital data for a billion years. When it comes to data storage, density and durability have always moved in opposite directions - the greater the density the shorter the durability.

For example, information carved in stone is not dense but can last thousands of years, whereas today's silicon memory chips can hold their information for only a few decades.

Researchers with the U.S. Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California (UC) Berkeley have smashed this tradition with a new memory storage medium that can pack thousands of times more data into one square inch of space than conventional chips and preserve this data for more than a billion years!

This video shows an iron nanoparticle shuttle moving through a carbon nanotube in the presence of a low voltage electrical current. The shuttle's position inside the tube can function as a high-density nonvolatile memory element. (Courtesy of Zettl Research Group)

"We've developed a new mechanism for digital memory storage that consists of a crystalline iron nanoparticle shuttle enclosed within the hollow of a multiwalled carbon nanotube," said physicist Alex Zettl who led this research.

"Through this combination of nanomaterials and interactions, we've created a memory device that features both ultra-high density and ultra-long lifetimes, and that can be written to and read from using the conventional voltages already available in digital electronics."

Zettl, one of the world's foremost researchers into nanoscale systems and devices, holds joint appointments with Berkeley Lab's Materials Sciences Division (MSD) and the Physics Department at UC Berkeley, where he is the director of the Center of Integrated Nanomechanical Systems.

He is the principal author of a paper that has been published on-line by Nano Letters entitled: "Nanoscale Reversible Mass Transport for Archival Memory." Co-authoring the paper with Zettl were Gavi Begtrup, Will Gannett and Tom Yuzvinsky, all members of his research group, plus Vincent Crespi, a theorist at Penn State University.

The ever-growing demand for digital storage of videos, images, music and text calls for storage media that pack increasingly more data onto chips that keep shrinking in size. However, this demand runs in sharp contrast to the history of data storage.

Compare the stone carvings in the Egyptian temple of Karnak, which store approximately two bits of data per square inch but can still be read after nearly 4,000 years, to a modern DVD which can store 100 giga (billion) bits of data per square inch but will probably remain readable for no more than 30 years.

"Interestingly," said Zettl, "the Domesday Book, the great survey of England commissioned by William the Conqueror in 1086 and written on vellum, has survived over 900 years, while the 1986 BBC Domesday Project, a multimedia survey marking the 900th anniversary of the original Book, required migration from the original high-density laserdiscs within two decades because of media failure."

The illustration shows the configuration of a new digital memory storage device consisting of an iron nanoparticle shuttle that moves through a carbon nanotube when a voltage is applied. This memory device can pack a trillion bits of data into one square inch of medium and retain that data for a billion years.

Zettl and his collaborators were able to buck data storage history by creating a programmable memory system that is based on a moveable part - an iron nanoparticle, approximately 1/50,000th the width of a human hair, that in the presence of a low voltage electrical current can be shuttled back and forth inside a hollow carbon nanotube with remarkable precision.

The shuttle's position inside the tube can be read out directly via a simple measurement of electrical resistance, allowing the shuttle to function as a nonvolatile memory element with potentially hundreds of binary memory states.

"The shuttle memory has application for archival data storage with information density as high as one trillion bits per square inch and thermodynamic stability in excess of one billion years," Zettl said. "Furthermore, as the system is naturally hermetically sealed, it provides its own protection against environmental contamination."

The nanoscale electromechanical memory device can write/read data based on the position of an iron nanoparticle in a carbon nanotube. The memory devices here are displaying a binary sequence 1 0 1 1 0.

The low voltage electrical write/read capabilities of the memory element in this electromechanical device facilitates large-scale integration and should make for easy incorporation into today's silicon processing systems. Zettl believes the technology could be on the market within the next two years and its impact should be significant.

"Although truly archival storage is a global property of an entire memory system, the first requirement is that the underlying mechanism of information storage for individual bits must exhibit a persistence time much longer than the envisioned lifetime of the resulting device," he said.

"A single bit lifetime in excess of a billion years demonstrates that our system has the potential to store information reliably for any practical desired archival time scale."

The multiwalled carbon nanotube and enclosed iron nanoparticle shuttle were synthesized in a single step via pyrolysis of ferrocene in argon gas at a temperature of 1,000 degrees Celsius. The nanotube memory elements were then ultrasonically dispersed in isopropanol and deposited on a substrate.

A transmission electron microscope provided high-resolution imaging in real time while the memory device was in operation. In laboratory tests, this device met all the essential requirements for digital memory storage including the ability to overwrite old data.

"We believe our nanoscale electromechanical memory system presents a new solution to the challenge of ultra-high density archival data storage," Zettl said.

This research was primarily supported by the U.S. Department of Energy's Office of Science through its Basic Energy Sciences programs.