University embarks on carbon nanotube data storage project, promises DRAM-like non-volatile memory

Trendwatch

By Rick C. Hodgin

Wednesday, November 12, 2008 03:30

Nottingham (UK) - Researchers at The University of Nottingham, one of UK's Top 10 universities, also ranking in the world's Top 100, stated yesterday that Project Nanodevice is underway. Their goal is to create molecular memory built of telescoping carbon nanotubes. "In this project a new device for storing information will be developed, made entirely of carbon nanotubes and combining the speed and price of dynamic memory with the non-volatility of flash memory." Telescoping a carbon nanotube The idea sounds simple enough; two carbon nanotubes of slightly different size, one resting inside the other like a two-member set of matryoshka (Russian dolls where each one has a smaller one inside). Electrical current will pass through the outer tube forcing the inner tube to telescope in or out. When out it will make contact with a remote electrode, thereby completing a circuit to create a binary one. When retracted the circuit will be broken - a binary zero. An artist's rendition of carbon nanotube memory in theory. (a) shows a full extended telescope and completed circuit representing a binary one. (b) shows a retracted telescope and an incomplete circuit creating a binary zero. Single-atom thick walls allow massive storage potential on the order of 10-100x more dense than modern flash memory with read/write speeds rivaling DRAM. This kind of memory will be a physical displacement of matter, meaning something has to move in order to switch states. Tiny, rolled sheets of graphene make up the carbon nanotubes, and these exhibit molecular properties which make the movements extremely fast and reliable, at least theoretically. Non-volatile, fast and friendly Another advantage of this system is that the memory will be non-volatile. Just like flash memory today, it won't need any power to maintain its state. It should also be extremely resistant to G-force induced state changes, such as accidental droppage. Even early generations of this technology should be as fast or faster than modern DRAM. Future computers using this kind of memory won't have a separate memory and hard disk for storage. Theirs will be a unified memory architecture built around this kind of storage medium, a new design paradigm for the instant on computer, one capable of continuous processing and data storage without ever swapping memory out to hard disk through paging. This one fact alone would greatly speed up our computer experience today. "Project"ions The project is being led by Dr. Elena Bichoutskaia, who said, "The electronics industry is searching for a replacement of silicon-based technologies for data storage and computer memory. Existing technologies, such as magnetic hard discs, cannot be used reliably at the sub-micrometre scale and will soon reach their fundamental physical limitations." Her goals, and the goals of the research teams working on this project, is a new memory device. According to Bichoutskaia, a new carbon nanotube memory product will be produced, one that will replacing DRAM and flash. With research of this nature there are no timeframes. Personally, I suggest a name for this creation, one in keeping with the finest traditions of existing memory naming conventions: CRAM (Carbon-nanotube RAM). "How many smaller nanotubes can I cram inside the bigger ones?" Perhaps future generations could move away from binary computers into ternary (or beyond) by having multiple tubes, like a real telescope. Source

Graphene could accelerate genomics

Oct 28, 2008
DNA moving through a graphene nanogap

Artist's impression of a DNA molecule (helix) moving through a tiny slit in a graphene sheet (shown in blue). (Courtesy: Henk Postma)

The “wonder material” graphene could soon be used to analyse DNA at a record-breaking pace. That’s the claim of a physicist in the US who has proposed a new way of reading the sequence of chemical bases in a DNA strand by sending the molecule through a tiny slit in a graphene sheet.

While the technique has yet to be verified experimentally, if successful it could be eligible for the $10 million X Prize for Genomics, which has set the challenge of developing a new rapid and low-cost sequencing technology.

The genetic profile — or “genome” — of an organism is determined by recording the full sequence of acid base pairs that make up its DNA. In 2003, the Human Genome Project made history by determining the entire human genetic code — 3 billion DNA base pairs that took 13 years to analyse using a technique that has changed very little since the late 1970s.

This “shotgun” approach first isolates a DNA strand and forces it to copy itself millions of times over in a chemical reaction. These are then “blasted” into tiny fragments because current techniques for sequence reading can detectors can only analyse very short sections of DNA. Finally, a supercomputer matches up overlapping base patterns to piece together the full genome.

No processing required

Now, Henk Postma at California State University Northridge has proposed a way of sequencing an entire DNA strand without the need for blasting or computer processing (arXiv:0810.3035v1 ).

Rapid Sequencing of Individual DNA Molecules in Graphene Nanogaps
http://arxiv.org/PS_cache/arxiv/pdf/0810/0810.3035v1.pdf

The technique involves cutting a very narrow slit or “nanogap” along the length of a piece of graphene — an extremely strong sheet of carbon just one atom thick. A voltage is applied perpendicular to the graphene’s surface, which causes the DNA strand to pass slowly through the slit one base at a time.

A second voltage is applied across slit and electrons are able to “tunnel” across the nanogap via the base that happens to be passing through the slit. There are four different types of base in a DNA molecule, and each should support a different tunnelling current — allowing the base type to be identified.

While the idea of sequencing DNA by sending it through a tiny gap is not new, previous schemes had relied on using separate materials for the membrane and electrodes — and aligning the two materials has proved to be a considerable challenge. Postma’s design gets around this problem by having the graphene function as both membrane and electrode.

Postma believes that detector could be made from a graphene sheet sandwiched between glass plates that are held together by van der Waals forces.

Technology should be possible

According to Changgu Lee, a mechanical engineer at Colombia University, some of the technology to realize Postma’s design may be available already. “Creating the nanogaps in graphene was demonstrated this year using both STM [scanning tunnelling microscopy] and catalytic cutting with metal particles”, he said.

Postma told physicsworld.com that traditional sequencing techniques are limited to determining about 800 base pairs per recording. By contrast, he estimates his design could yield 100,000 bases per recording, and if run continuously it would read the whole human genome in two and a half hours. He also believes that his technique could lead to sequencing devices that are smaller and cheaper than existing systems.

If successful, Postma's system could be a contender for the X Prize for Genomics, which aims to award $10m to the inventor of a device that can sequence 100 human genomes within 10 days or less,to a specified accuracy and costing no more than $10,000 per genome.

Postma said he is continuing to develop his design, but added: “I published the paper to get feedback from the scientific community, in the open, because I believe that will lead to the best possible technology.”

And it seems DNA experts are ready for a new technology. Geoffrey Baldwin, a molecular biologist from Imperial College in the UK said “to truly develop health care we need the profile of 100s of genomes not just the few we have at the moment”. He added “there is now a great opportunity for a new technique to become the standard in base sequencing”.

About the author

James Dacey is a science journalist based in the UK

Source

Strikes me as a DNA computer in the making.