[extropy-chat] Re: garage nanotech

[dgc at cox.net]

> From: <kevinfreels at hotmail.com>
> Robert said:
> 
> >With respect to dry nanotech one is going to need something
> >like STMs with tips that can be exchanged to do reliable and variable
> >chemistry -- and its going to have to be highly parallel to be useful.
> >When we get that I'd have to guess (completely off the wall) sometime
> >in the next decade.
> 
> Dan? How's that STM coming? Have you thought of maybe redesigning
> in a way that you can do this?
> 

Alas, I must crawl before I can walk. An STM is member of a class of devices know as SPMs (Scanning Probe Microscopes.) The STM depends on tunnelling current to measure the tip-to-sample distance. Other types of SPMs include AFMs. These devices use different principles. I have not found a way to make a cheap AFM tip and sensing mechanism. Note that the unimorph actuator is so cheap that it it cheaper to build an AFM from scratch than it is to modify the STM.

The sensor/effector is only one small part of the problem. The biggest problem, I think, is simultaneous sensing and effecting, and precise registration when using multiple tools. A slightly easier problem is that an SPM is usually a 3-axis tool, while we need a 6-axis tool. I have grandiose delusions of solving all of these, but I refuse to spend time on them before I actually get the STM working.
If I cannot solve the simple problem I don't want to attack the harder problems. Until you see me publish a scan of a HOPG substrate, don't assume I'll succeed.