Chris Phoenix is providing live blog coverage for us on all the presentations from an important conference on Productive Nanosystems: Launching the Technology Roadmap...
Next talk: Dave Leigh, School of Chemistry, University of Edinburgh, UK
Tooling Up for the Nanoworld
Nature already has a nanotechnology: nanomotors and structures and materials and catalysts... all done with molecules.
Lessons to learn from biological machines:
- Soft not rigid
- Work at ambient temperatures
- Utilize chemical energy
- Work in solution or at surfaces
- Effect of scale - constant motion
- Rely on Brownian motion
- Made by self-assembly
- Governed by non-covalent interactions
- Statistical mechanics not Newtonian mechanics
- Require architectures which restrict degrees of freedom
- Operate far from equilibrium
[Ooh, I wish I had time to answer these point-by-point! This is basically a direct attack on diamondoid, and each point has an answer. In fact, I've already answered many of them over the past four years in my science essays though I shouldn't take too much credit because the answers have been known for quite a while.]
Random motion can be "harnessed" to do work, if you have a randomizing force, an anisotropic medium, and a "fuel" energy input (or information, which requires energy). [I've never quite been sure why you're said to be harnessing the motion rather than the fuel.]
He talked about several kinds of ratchets: if you change the potential energy "surface" that the particle experiences, then you can make the particle move without directly touching it. Like rolling a marble on a blanket by lifting up parts of the blanket. There are several ways to do it; they look quite simple and intuitive. There may be some reason why it wasn't obvious that these would work except in hindsight, but it's hard to see how they could *not* work given basic conservation laws.
The application to his molecular motors seems to be that the motors aren't moved directly by force, but jiggle themselves into the most "comfortable" position given some change (light, etc) applied to part of the molecule.
A motor that hides or exposes a fluorinated region can make a droplet of liquid move over a surface: movement of millimeters due to movement of nanometers. Kinda' cool, molecules controlling a macroscale object.
Starting with two ring-like molecules strung on a larger ring, he can make the small molecules move in a circle around the ring by hitting the ring they're strung on with two different colors of light in alternation, to bump first one and then the other molecule off its resting place.
There was a discussion of a "Maxwell's Demon" which is a thing that can't exist because it violates the laws of thermodynamics... except that he's built a molecule which squeezes a ring over to one side when you shine light on it... and there's some verbage accompanying the phenomenon which makes it sound counterintuitive. But I can't help suspecting that a different explanation would sound much more intuitive, somewhat less mysterious, and just as cool from an experimental point of view.
Chris Phoenix
Tags: nanotechnology nanotech nano science technology ethics weblog blog
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