User:WillWare/Homebrew probe microscopy

There are some cool projects out there to build homebrew atomic force microscopes and scanning tunneling microscopes. Both of these kinds of microscopes can get images down to the level of individual atoms.

One of the coolest of these projects is http://www.geocities.com/spm_stm/ posted by John Alexander, who has a considerable background in scanning probe microscopy. What I find most brilliant in his work is his idea for modifying a single inexpensive piezoelectric element to provide all three degrees of freedom at nanometer scales, and he manages all this with an X-acto knife. I bow to his astonishing ingenuity.

My hope with this page is to put together enough information to make it falling-off-a-log easy for anybody to make their own probe microscope. Every high school should have one.

17 Jan 2010
For a while I was thinking about whether it would be cooler to make an AFM or an STM, and thinking an AFM would be better because it doesn't require that the sample be conductive. But an AFM must necessarily work in high vacuum because otherwise the signal is swamped by Brownian motion whacking the cantilever on all sides (or any mechanism that might be used in place of a cantilever). As far as I can see, an STM should have no such requirement to operate in vacuum, though doing so would probably be advantageous.

Would it be possible to create a very small region of high vacuum on a hobbyist budget? I was thinking maybe if you can liquify the air in a small space, that might do it. This would be done by lowering the air temperature using liquid nitrogen, which is considerably colder than the boiling points of oxygen, argon, and carbon dioxide, the other major components of air. So you'd have a little nitrogen vapor pressure but otherwise you'd be OK.