Sacha De’Angeli from ChemHacker has released the schematics and source code of the Scanning Tunneling Electron Microscope. The STM is Arduino based and has been a build in progress for quite a long time now. Looks like it is at a great state now! See the Wikipedia page for more generic information about Scanning Tunneling Electron Microscopes.
“The STM is based on the concept of quantum tunneling. When a conducting tip is brought very near to the surface to be examined, a bias (voltage difference) applied between the two can allow electrons to tunnel through the vacuum between them. The resulting tunneling current is a function of tip position, applied voltage, and the local density of states (LDOS) of the sample.[4] Information is acquired by monitoring the current as the tip’s position scans across the surface, and is usually displayed in image form. STM can be a challenging technique, as it requires extremely clean and stable surfaces, sharp tips, excellent vibration control, and sophisticated electronics.“