With an 80 cent piezo buzzer, tungsten wire and some spare MDF, Dan Berard has managed to build an working Scanning Tunneling Microscope that can image whole atomic structures. Arthur C. Clarke once said that any sufficiently advanced technology would be indistinguishable from magic…
…my variation would be “any sufficiently advanced technology made in your house is probably magic.”
Because this, at first glance, is pure magic.
Inspired by John Alexander’s simple STM project in 2003, Berard has taken DIY Microscopy to a whole other level; generating higher resolution pictures for magnitudes less in cost.
Scanning Tunneling Microscopy is, on paper at least, a relatively straightforward idea. An electrically charged tip, sharpened to within a few atoms, is brought close to the surface whatever is to be ‘scanned’. As the tip passes by each atom, their electrons ‘tunnel’ towards the tip, altering the level of charge and denoting the existence of an atom. In a way, STMs don’t ‘see’ atoms like an ordinary microscope, but nevertheless, they are most certainly there.
Berard’s STM follows exactly the same principals, relying on a wholly different of materials. Unlike other DIY STMs, a substantial number of the components are pure hacks. For example, the STM tips are cut from 30 AWG tungsten wire, pulled from the wire-cutters in such a way that he can reach the needed sharpness. Although, as he says, ‘the results aren’t pretty’, it does work for scanning high-grade graphite (HOPG) (pictured) as it very flat and ordered.
At the heart of the scan head is the piezo buzzer, the sort you see in Doorbells. Cut into quadrants, they can act as very simple ‘stack actuators’ that use vibration to move the scanning tip in any direction. To reduce the effects of thermal expansion and to better electrically insulate, sapphire is used for mounting the scanning tip while high-precision adjustment screws from McMaster-Carr control the Z height.
The sample is mounted on ‘a penny with copper tape and stick it to a magnet mounted on the STM base.’ Berard, in his infinite glory, has posted nearly every element of the project, including blueprints and circuit diagrams, so that you too can make a DIY STM.
It seems incredible that only twenty years ago when we were looking at pictures of atoms and were reading about the massive machines needed to refine microscopes to that level. Now, with a spare week and a few hundred dollars, it’s unbelievable what one can do it at home using commonly found tools and equipment.
Hat Tip to Hackaday