From: Robert J. Bradbury (bradbury@aeiveos.com)
Date: Thu Jan 24 2002 - 14:36:52 MST
On Thu, 24 Jan 2002 hal@finney.org wrote:
> I was surprised to read:
>
> > The Casimir effect is already a problem for fabricating MEMS devices
> > because at very short distances free surfaces tend to stick together,
> > said Mohideen. "During the fabrication step, it is very hard to make
> > free moving surfaces such as cantilevers [and] bridges which are
> > separated by short distances," he said.
>
> Drexler's book Nanosystems has a great deal of analysis of friction
> and the forces experienced by atomically-smooth surfaces in contact.
> However I don't think he discusses the Casimir force. It sounds like it
> could be a significant factor in the kinds of nano- mechanical designs
> that Drexler considered.
The problem is people extrapolate MEMS problems to NEMS problems.
Most of Eric's work assumes there isn't a 10 nm gap between the surfaces.
If there were significant Casimir force problems, one would expect
there to be problems with the sliding or rotating buckytube within
a buckytube bearing. That doesn't seem to be the case from what I've
seen experimenters claiming. Or perhaps the forces involved are simply
so small that the application of electrical, electrostatic or mechanical
forces is simply overwhelming the Casimir force.
We need harder numbers here on the amount of force/atom the Casimir
force can produce.
Robert
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