Nanowires get connected: Nature

Ivan Seeking

Molecule-sized switches regularly prompt headlines about a new generation of miniaturized electronic chips. But there's a catch.

Although researchers can shrink individual components of circuits to the nanoscale, they cannot wire them together without conventional connections, which are hundreds of times bigger than the components themselves.

It's akin to joining the latest Pentium chip to your computer with enormous crocodile clips and jump leads. "You lose most of the advantages you had in this very small structure," says Charles Lieber, a chemist from Harvard University, Massachusetts.

Now Lieber reckons he has the answer: a technique that could be used to create ready-wired nanocircuits that do not need cumbersome connections. [continued]

http://www.nature.com/nsu/040628/040628-16.html

zoobyshoe

When I read, several years ago, about the first "nano" accomplishment in Time or Newsweek or somewhere, I had instant doubts that the people had accomplished what they claimed to have accomplished, which was to pick a molecule up, transport it to a desired location, and deposit it at that location. They claimed to have written out the letters IBM this way.

I didn't doubt that they could pick up an individual molecule, but the notion that they could accurately position it is just not believable to me. The notion of positioning enough of them to create a letter of the alphabet is just that much less credible.

My several years of work in various machine shops where staying within a tolerance of +- .0005 inch on location is something only the most expert machinists could accomplish leads me to conclude that the notion of setting a molecule down, moving your carriage to pick up another one, then moving it back and positioning it to within a couple molecular diameters of the first position, is not possible to achieve.

I understand that they use ultra precise equipment, and work in dust free, and temperature controlled rooms, but the fact remains that matter, metal included, is just too elastic to reliably "repeat" at the level of a molecular diameter.

What I found kind of sad about the first claims was that, while they had a computer generated image of what they imagined the result looked like, they had no way to actually check the result. All that they had to report was that a guy had sat there and gone through the steps of creating this IBM image in molecules, but no one really knew if he had or not.

Anyone know if they have developed a reliable way to check their work?

Ivan Seeking

That's the first I have heard of this. Do you have any links? I always thought that I had seen an electron microscopic image of the IBM letters.

It seems that more advanced techniques do not rely on mechanical precision.

Controlling molecular deposition and layer structure with supramolecular surface assemblies

Selective non-covalent interactions have been widely exploited in solution-based chemistry to direct the assembly of molecules into nanometre-sized functional structures such as capsules, switches and prototype machines. More recently, the concepts of supramolecular organization have also been applied to two-dimensional assemblies on surfaces stabilized by hydrogen bonding, dipolar coupling or metal co-ordination. Structures realized to date include isolated rows, clusters and extended networks, as well as more complex multi-component arrangements [continued]

http://www.nature.com/cgi-taf/DynaPa...=doi1088924917

zoobyshoe

No, I have no links. I just recall something to the effect of "This is what it would look like if the technology existed to see it," sort of explanation of the picture.

If they could get an electron microscope image of it, that would certainly constitute proof. The article I saw did not have one, though. Just a computer generated image of what they supposed it looked like.

With these other methods of assembling them I would bet they have means of testing them to see if they're arranged as hoped. I don't think the electron microscope can get an image of a molecule. I'll check a bit and see.

zoobyshoe

Most sites were about its use in biology. This one has to do with looking at semi-conductors. It seems to be saying something to the effect that they can sorta get a useful idea of things at the atomic level. That being the case, maybe the computer generated image was based on some of this sorta useful information from a scope like this.

SSD History - Electron Microscopy
Address:http://www.ssd.ornl.gov/History/ElectronMicroscopy.html Changed:9:30 AM on Wednesday, January 27, 1999

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