DNA Strands as Semiconductors

Dyslexic writes "ABCNews is reporting that strands of DNA can act like semiconductors. After seeing "The Matrix" this makes me only fear the future." The research is coming from two researchers in Basel, Switzerland. Essentially, this research is saying that while DNA makes a good semiconductor, it does not conduct as well as, say, copper. It's real usefulness comes from the fact that "...he knows of no metallic wires that can be made as small or as regular as DNA strands. A strand is 2 billionths of a meter thick, or one-forty-four-thousandths of the diameter of a medium-size human hair ". Uber-thin. I like it.

Comments

Atomic Wires are cool, not molecular

[BadlandZ]

Seems that this subject comes up about every six months here on SlashDot. Interesting spin with the DNA this time. I will have to dig a little bit to respond with a 100% confidance factor, but I will tell you right now, I doubt some of this.

I have looked very deeply into the field of "molecular wires" and found several flaws. The published journal articals on this that I know of all use a high level of congugated pi bond interaction as the mechinism for the transport of electrons. Although this produces a remarkable increase in electrical conductivity compared to a "normal" molecule, the ability to conduct electrical current still drops off exponentially as a function of distance. Or, in other words, unless the whole circut is only a few ~30 atoms long, it would require enough juice to totally distroy it to get any electrical flow across it!

Now, there is the possability of "bundleing" these systems, maybe using something such as carbon nanotubes (maybe several of them built one on top of each other) to overcome this, but the fabrication process for doing something like this is more science fiction right now than science. Maybe that's what they are trying with the DNA stuff, but from what I know, it's not possable.

But, AGAIN, I point to a possability that is realistic. If you look at some of the work done in IBM labs, specifically The Almaden Lab and the one in Zurich (don't have the URL on hand, but there is one), you can see something that would be superior on TWO counts. Actually using indivual atoms insted of full molecules. Positioning highly conductive METAL atoms (not carbon molecules) on a semiconductor surface (carbon), it might be possable to create a circut that would stand a much higher chance of working, AND be much smaller. Right now, I believe that IBM is using this technology to try to work towards data storage at an atomic level, which, in theory, could fit the Library of Congress on a postage stamp. ;-) But even this work is limited, AFAIK, to very low temperature (like 10K?) and is not truely practical.

But, this shows more hope, as I have seen a few research groups position molecules (buckyball) with STM on a surface at almost room temprature. To me, at least, this is much more realistic, and much much more exciting research.

Sequencing by electrical means?

[BadlandZ]

You actually might just need something like an AFM, if you could get things in the right environment. Zone Electrophoresis (spelling?) to denaturalize the strand and line up the groups as you could predict, then just AFM (Atomic Force Microscope) them... ? K, off the wall idea, maybe not, it's not my field. Sorry.

The potential to rapidly get the sequence of a DNA strand is a very hot field, and very heavily government funded. Based primarily in the Human Genome (spelling?) Project, I believe. So, I don't doubt there is a lot of work on rapidly "reading" DNA.

But, this begs the question, how are you going to accurately build long strands of DNA, sequenced exactly as you would like them to be, in order to store data on them? And, why DNA? Potentially, you could use something easier to detect (cool tagged or marked base pairs if DNA, or something totally diffrent), and easier to build?

Quantum Effects.

[BadlandZ]

Of course, that's where it gets fun to think about and read about. The potential for structuring switches... etc...

Not a limitation, but a new field of investigation. Classically, electronics is something that has been looked at very one dimentionally. Consider the switch set to off, and not only are you stoping flow in a liniar direction and influancing one data point, your have a flow of electrons tunneling into bulk, and influancing the behaviour of the whole circut.

Yes, it's not a classical model. But, I don't believe it's an unusable consept. Gates and switches have a much wider base from which to be developed. And, the actual movement of an atom from the tip of an STM is one of the first examples of something with known physical mass actually tunneling! Wahoo... think, this is not as we know it, this is new, and of course it's not classical, by any sence, but, that also means it's not subject to classical limitations.

Nice enough, but...

[HvK]

Wouldn't it be much better to concentrate on getting mechanical nano-computers to work on this kind of scale rather than building smaller electric ones? (Please read K. Eric Drexler's "Engines Of Creation".) Strikes me that's the more worthwhile avenue of research, especially since we'll be hitting more and more problems with electron tunnelling and at those scales nano-mechanic movement actually could be fast enough (I think) to overtake electrical impulses (unless they'd be travelling in a perfect superconductor).

Never mind all the other goodies we could get with nano-machines! ;]

Herbert von Kammerstein