Nanotech Motors, Biotransistors, DNA Fractals

FleaPlus writes "The American Institute of Physics has a news bulletin describing a couple of interesting nanotech advances. The first is the smallest electric motor in the world, made by Alex Zettl's group at UC Berkeley. The second is a single-protein wet biotransistor. Additionally, Technology Research News reports on algorithmic self-assembly of DNA Sierpinski triangles, by Erik Winfree's group at Caltech."

Comments

Coral Cache

[Anonymous Coward]

Take it easy on those Berkley servers. Coral Cache:

Computer-generated movie shows an artist's conception of the operation of the relaxation oscillator, and a possible application. Created by Kenny Jensen

TEM video data showing an operating relaxation oscillator, with explanatory text overlaid.

Re:Coral Cache

[Capt'n Hector]

Berkeley has a 4xOC48 line last I heard. NYU will go down before Berkeley does...

Help

[elid]

for those of us who aren't fond of arcane geometrical shapes (or Google, for that matter)

definition of "nano-"

[bcrowell]

Nanotechnology has gotten a reputation for being a flaky area of research. Part of the problem is that the word "nanotech" sounds cool, so people tend to use it without defining what they mean. Eric Drexler originally defined it in terms of machines that worked at the molecular level, i.e., on scales of a few nanometers. The problem is that there are fundamental reasons why it's extremely difficult to construct machines on that scale, and in the 20 years since he published Engines of Creation, basically nothing has happened to realize his original vision. Meanwhile, people have been making smaller and smaller machines via techniques that would never be able to scale down to the scales Drexler had in mind. The wikipedia article distinguishes between "nanotechnology" and "molecular nanotechnology." The Berkeley group's motor, for instance, is clearly on a scale (hundreds of nm) that is not molecular nanotechnology.

Re:definition of "nano-"

[Goldsmith]

Drexler's book was conceptually great and really pumped a lot of interest of the subject into the general public (his second is another thing). However, Engines of Creation makes a few assumptions about the molecular world which have been found to be incorrect. Diamondoids are not as stable a form of carbon at the nano scale as he thought, and materials are inherantly different from the bulk at the nanoscale. For example, a relatively inert metal such as gold becomes extremely reactive when clumped into just a few isolated atoms. The reason nothing has happened to realize Drexler's original vision is that it did not work, his detals were wrong. It's not as easy as drawing lines between carbon atoms to make the shape you want. Since then, Drexler has refined his own definition of nanotechnology into something which can be described as artificial biology in arbitrary environments. This is a common definition of nanotechnology among the majority of people who study it. Like Drexler, most of the people studying nanotechnology come from a biology background. They tend not to like the atomic or solid state approaches used by physicists and engineers, so they call their work "molecular nanotechnology" to differentiate themselves.

Zettl is a physicist, and comes at things from a very different perspective. I had the opportunity to see this research presented at an invited talk a few weeks ago at the last APS meeting. It is most definitely nanotechnology on the level of single atoms. Let me explain:

Their "motor", as presented at APS, consists of a resevior of indium atoms at one end of a carbon nanotube, and an indium crystal on the other end. By driving a current through the nanotube in conjuction with heating from the TEM electron beam, they are able to move the indium from the resevior to the crystal and back. The atoms move very quickly, they do not have the time resolution in the TEM to see them. The crystal, on the other hand, grows very slowly, and they are able to see individual atomic layers being deposited on this crystal which is only a few nanometers in diameter. The height of the crystal they can vary from nothing to microns. The whole motor is actually smaller than the smallest linear biomolecular motor (kinesin), hence the "smallest motor" claim.

Thus the fundamental technology is atoms, and is nanoscale. Furthermore, to call this technology "not nanotechnology" is absurd! This is the technique that may enable atomic construction. The ability to move individual atoms around very, very quickly and in an extremely controlled manner is essential to "Drexler's vision", as you call it. Imagine an array of carbon nanotubes, each with a resevior of a different metal at one end, which can be scanned across a surface like an inkjet printer head, depositing atoms on a surface. You would then have "atomic nanotechnology", which is what Feynman's original vision actually was.

Re:Around here we call it 'life'

[Anonymous Coward]

Difference is control. People have been doing self assembly for ages, but can you do a self-assembly at one precise location. That is what makes chemistry different from modern day nanotechnology. The ability to do more complex things (just not assembling) and make precise measurements at the desired locations (not the entire film). I am sorry you are way to insecure about your profession.

Re:How does it work ?

[Anonymous Coward]

I am not sure if I understand the power density claims.

That's because they're really not meaningful. You can't compare it to the Sun (or a Toyota), because 'power density' in a macroscopic sense isn't the same thing as in the microscopic sense.

For example, if you wanted to, you could calculate the 'power density' of a single atom or an electrical current, dividing the current power by the volume of the conducting electrons. That'd certainly give you a very high number - electrons are small - but not a very meaningful one.

As slashdot says: If you're using these numbers for anything serious, you're crazy.

Re:The DNA trick is particularly disappointing

[realbadjuju]

I didn't RTFA, but I've read many of Eric's papers and met/conversed with him several times. I don't see what the problem is with the error rate. Yes it is high, but my understanding is that what Eric is trying to do is harness the massively parallel nature of DNA based computation, remember Avagadro's number is a very big number, and not develop a novel kind of information storage. Also, since no one has done this yet, he obviously has to start with simple problems, eg the Sierpinski experiment and the counting in binary experiment, both of which only used a few (2 to 3) different tile types. However I think his latest (unpublished) experiments use something on the order of 20-30 tile types. As for a cubic lattice, people have made single 3D polyhedra, though I can't remember their names, and it would be simple to create a lattice out of these. But then the problem becomes one of looking at the lattice to "read" whatever information there is. Eric is imaging these structures with an AFM (atomic force mircoscope) which could not "look inside" and 3D lattice. The lattice would be far too small to use light based microscopy and the energies involved with a regular electron microscope would literally blow the lattice apart. Maybe cryogenicly cooled scanning confocal electron microscopy (google Nestor Zaluzec at Argonne) would get you something but I don't know.