Interested In Science?

Well, it has been rumoured for a while now and its properties as a potential silicon-replacement have been exhalted for several years, but it looks that finally the worlds smallest transistors will be graphene based.

In science yesterday a team at Manchester have reported the development of a transistor made of graphene only 1 atom thick (graphene is a flat molecule - the graphite in your pencil is many sheets of graphene) and 10 atoms long.

This is (pardon the magnitude-based pun) huge news!

Ever since Richard Feynman’s lectures on the potential for miniaturization of circuitry, nanoscience has been one of the (if not in fact THE) fastest growing areas of science. And this latest development is at the very frontier and epitomizes what I’m sure Prof Feynman was hinting at.

The paper can be read in full at the following link (if you have access). If you don’t there is a well written commentary here on the BBC website.

There is also a commentary (Science Perspective doi: 10.1126/science.1156936) on Graphene in the journal science through this link.

The paper from the Manchester group is cited below.

Ponomarenko, L.A., Schedin, F., Katsnelson, M.I., Yang, R., Hill, E.W., Novoselov, K.S., Geim, A.K. (2008). Chaotic Dirac Billiard in Graphene Quantum Dots. Science, 320(5874), 356-358. DOI: 10.1126/science.1154663

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I remember posting sometime late last year about the potential for even more memory in your iPod (160Gb just isn’t enough!?!) - Atomic Memory Storage…(01/09/2007) - but here is yet another hint at what the future has in store for us…

Published this week in Science a team at IBM have declared they have a novel way of successfully storing fast and stable memory in something called ‘racetrack’ memory. The idea is that memory is stored on nanowires, and electrons are pushed around the track, moving domains which can be charged one way of another, ultimately as 1 or 0 (binary storage) depending on which way the domain is magnetized.

The journal article is cited below, but the following link should take you to an introductory article in science which explains the science (and controversy it’s causing) with a bit more detail.

http://www.sciencemag.org/cgi/content/full/320/5873/166?rss=1

Hayashi, M., Thomas, L., Moriya, R., Rettner, C., Parkin, S.S. (2008). Current-Controlled Magnetic Domain-Wall Nanowire Shift Register. Science, 320(5873), 209-211. DOI: 10.1126/science.1154587

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Ha ha! At last some certifiable published research/progress on the flat-screen/organic electronics-printing front (sorry for that appauling intro…it’s early).

Japanese scientists have published in PNAS (see citation at bottom - next edition) a method to reliably print flat screen panels using a fancy new inkjet style printer (see also BBC News). The technique allows them to circumvent the problems of todays silicon-based flat panel printing processes which in order to obtain maximum purities and performances have yielded to higher processing temperatures, increased manufacturing costs, and thus a higher price for the consumer - exactly what plastic electronic technology is designed to help combat.

The inkjet printers are able to print dots of 1 micron (a millionth of a meter, 1×10-6m, a thousandth of a millimeter…very small!) on to a flexible organic semiconductor. Current printing techniques are limited in their abilities to replicate the resolutions achieved by silicon-based devices and other lithographic techniques for several reasons - one being surface tension of the inks. This new printing technique allows droplet volumes of less than 1 femtolitre - a millionth that which recent techniques allowed.

All in all…yes! Very happy with this development.
See citation below for full article…

Sekitani, T., Noguchi, Y., Zschieschang, U., Klauk, H., Someya, T. (2008). Organic transistors manufactured using inkjet technology with subfemtoliter accuracy. Proceedings of the National Academy of Sciences DOI: 10.1073/pnas.0708340105

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Nature (and the BBC) are reporting a development in nanowires - their potential for integration into fabrics, which when moved (or worn and moved about in) will allow the build up of charge. The gold-coated nanowires work on a piezoelectric principle - a mechanical input generates a charge, for instance as the nanowires rub against each other.

I think this falls in step behind the cellulose paper covered in nanotubes (paper battery) discovery late last year - infact it is a logical progression of the technology, one which I hope will be pursued; my sony ericsson phone batttery has the life- span of a fruit fly!

Medical applications are bound (internal inplants etc) to be considered, but I want to know when I’m going to be able to plug my iPod into my jeans and when digital cameras come with a T-shirt adapter!?

abc

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The reason behind this vague subject matter is the lack of time I have had to concentrate on any single specific development in the recent press (read the ABOUT ME page if you are wondering where my time goes), and simultaneously the fact that recently, in the attempt to find some focus of interest, I have been besieged and, admittedly, a little distracted, by a) the increase in interest in my site (~400 hits per week mainly on OLED hits) and b) the amount of literature being produced out there ‘on the web’ about such a wide variety of subjects WITHIN nanotech (my favourite area of the vast and all-conquering discipline ’science’) that I think it is stupid to try and concentrate on one area when there are issues out there that need to be covered which cover the whole science area.

That incredibly long winded introduction was a means of covering my lazy behind for momentarily focusing on the more recent news in nanotechnology that concern cancer detection, nanotube applications and, of course as is always the case with such ground-breaking, newsworthy innovations their inevitable governing, restriction and enforced guidelines as set down by Uncle Sam (the US gov) and Uncle Keith (UK’s gov with, in my opinion, a particularly apt nomenclature).

Already concerns are springing up over the possible problems caused by the new products and technologies allowed by nanomaterials. Regardless of their potential for amazing advances in the fields mentioned above their possible hazards are being called into question (FDA finds no proof of harm with nanotech products, Editorial: Governments differing over Nanotech safety). Fortunately, the FDA has, as yet, found no evidence that these nanomaterials now being included in everything from cosmetics (eg. sunscreens) to sports equipment (eg. baseball bats) pose a significant threat.

I guess it is a good thing that these things are treated with suspicion, seeing as these nanoparticles are being used to address cancer-detection, and it would be an horrific irony and potential legal-minefield if the detection system helped induce secondary cancers in the patient.

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This may sound like madness, but IBM are on the way to discovering how to use single atoms (!) and molecules to store pieces of data. Thus the transistor on computer chips of today is being shrunk to a 1000th of the size!

This is being made possible by the virtue of something called anisotropy, which pertains to a property dependent on direction; in this case a magnetisation effect also referred to through a quantum dynamic property as spin. Due to the spin quantum number of any atom essentially being either up or down (i.e. 1 or 0…ringing any bells??) this property can be exploited towards the storage of binary data!

For more on this break-through read up at ScientificAmerican.com.

As I have covered in Plastic Electronics: Explained and probably several posts about nanomaterials or plastic electronics, silicon based computer chips are approaching their physical limits of ’shrink-ability’. By this I mean the break-down of the quantum abilities of the materials once certain components of them become so small that they are unable to do what they should (namely, the gate-oxide in a silicon transistor is becoming so thin that soon electrons will be able to tunnel through and it will no longer be an insulator).

So as you can imagine, in order to keep up with the infamous Moore’s Law and maintain the linear increase of transistors-per-chip, ways to circumvent this issue have been being researched for several years, from several different directions.

One of the latest efforts to show promise is from a group of researchers in Hong Kong who have incorporated the use of carbon nanotubes instead of the copper or tungsten ‘plugs’ to interconnect the layers of silicon semiconductor. This doesn’t remove the use of silicon, but does take a stab at improving the ability of companies to make ever-smaller/powerful microchips.

Read more here at the patent application, and here at NewScientist.

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On the flying coat tails of nanobattery post from a couple of weeks ago comes this revelation from Scientific American, NewScientist and the BBC News pages.

Paper Batteries. Sounds stupid. Reads very interestingly. BBC News says,

‘[The researchers] have produced a sample slightly larger than a postage stamp that can release about 2.3 volts, enough to illuminate a small light.’

Professor Robert Linhardt from the Rensselaer Polytechnic Institute believes this allows us a ‘glimpse into the future…’. He also says that controlling the quantity of out-put power should be relatively easy due to the nature of paper - stack several sheets together, rip it in half etc etc.

They are made by the incorporation of carbon nanotubes onto cellulose paper. Carbon nanotubes have relatively enormous surface areas and consequently storage of charges on these surfaces clearly enables battery-like abilities.

Read the reports here:

http://news.bbc.co.uk/1/hi/technology/6945732.stm

http://www.sciam.com/article.cfm?articleID=61525146-E7F2-99DF-368134A7014B95DE&chanID=sa003

http://www.newscientisttech.com/article/dn12480-nanotubes-turn-paper-into-a-power-source.html

This is a great development, although how reliable and practical these devices turn out to be remains to be seen.

interestedinscience.com © 2007

Now, I know most (actually at this time and date, it’s all!) of the blogs and pages written here are strongly pertaining to nanomaterials and plastic electronics, but this one I feel needs special attention because it is such a simple yet essential component of any electrical circuit. The power supply!

I have read literally hundreds of papers on dozens of different aspects of plastic electronic componentry, from molecular wires to OLEDs that can also act as light harvesting devices (photovoltaics), i.e. the simplest to the more complicated issues. I had not heard of any developments regarding a nano-scale power supply - or nanobattery, probably because I hadn’t really considered it. I have now…

One of the most recent RSS Feeds from NewScientist regards the invention of a biological nanobattery. It sounds absurd at first, but when the principle of a battery is analysed it makes sense.

A battery is just a combination of materials that allow the semi-permanent storage of a charge, due to the nature of the differences between the materials’ potential differences and electromotive forces.

I was curious as to how this principle could be adapted and implemented on the nano-scale, and was pleased to see such a simple process described. NASA decided to investigate the use of the protein ferritin, an iron-based compound that can carry either a negative or positive charge. Ferritin already has a use in materials science as a reagent in the preparation of carbon nanotubes, but its use as a major constituent of a nano-scale device is novel.
NASA’s proposed capacitor is based on a system of layers of oppositely charged ferritin, deposited by spin coating one on top of the other, until sufficient layers are present to enable charge storage between them. Unfortunately the only further information I could find on this research is a rather legal-term-dense patent application (see the NewScientist website), but if I find anything more about it I will share it here asap.

To be thorough on the subject I did a quick literature search on nanobatteries, and was pleased and somewhat surprised to discover that there has been a significant amount of research done - and this ferritin-based cell is not the only sort out there.

In 2004 mPhase Technologies in association with Bell Labs claimed to have successfully prepared the first nano-battery. A report said the battery was
“…based on a Bell Labs’ discovery that liquid droplets of electrolyte…stay in a dormant state atop…nanograss until stimulated to flow…triggering a reaction that produces electricity”
Unfortunately, yet again, I couldn’t find any useful journals or articles relating to this report, but I shall keep looking - and if anybody out there knows something, please drop a comment!
Nano-batteries are an inevitable feature of a nano-tech device, and since these devices are becoming more and more popular I think any developments in this power-supply area are worthy of reporting.

interestedinscience.com © 2007

A break from plastic electronics here, but not from chemistry, or even nanomaterials!

A group of scientists in Alberquerque, New Mexico, have synthesised superparamagnetic nanoparticles in a material with the functional ability to bind with cancerous cells. This allows the cancerous cells to then become themselves magnetized. A magnetic probe can then be used to collect the cancerous cells, removing the need for repeated invasion of the host to collect biopsies, which can be a painful as well as prove inaccurate.

A biologically compatible material is impregnated with these nanoparticles of magnetic iron oxide, and then coated with an antibody that binds indiscriminately with some cancer-based chemical. Hence, the material seeks and binds with the cancer, and the nanoparticulate superparamagnetic iron oxide magnetizes the system, enabling detection and capture with a magnetic probe.

The use of magnetic nanopartcles is common place now as part of several analytical procedures in medicine, the most common and famous being in MRI (magnetic resonance imaging). Here nanoparticles of iron oxide, such as the commercially available Feridex I.V. by Advanced Magnetics Inc., are used as contrast reagents and can be made to specifically target certain organs (Feridex I. V. targets liver lesions). Another use of magnetism in medicine is in the use of SQUIDs (superconducting quantum interference devices) to detect nanoparticles which have been attached by a similar method to above to T-cells, which allows an early and non-invasive method of detection of rejection of a transplant organ. The SQUID array is also used to allow an image of the targeted cells to be captured, and is so sensitive that only a few milligrams of the nanoparticles need to be injected.

I hope that this technology proves to be as useful (if not more!) than the paper suggests, as recently nanomaterials have got a bit of bad press due to their as-yet unknown long-term side-effects. I have personally done some work with nanomaterials (well, qunatum dots to be more precise) involving tagging with fluorescent dyes, and I must say how visually stunning the results are, as well as the ease of preparation. Unfortunately our exercise was purely academic (a ‘can we do it?’ mentality if you like) so there are no real results to report. However! This does not shake my belief that nanomaterials have still got a lot to offer, and although the side-effects are unknown, I hope the exciting research continues unabated.

For more on the aforementioned magnetization of cancer cells see Phys. Med. Biol. 2007 52 4009 and the article at NewScientist.co.uk

For more information on the use of SQUID arrays for determining transplant rejection see J. Magn. Magn. Mat. 2007 311 429.

For more information about nanomaterials and nanotechnology in general see the latest magazine edition of NewScientist.

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