Project Announcement: Design/Build of an STM

Bare main board, stuffed main board, and a microscope head board.

As I mentioned in yesterday’s radio interview, I’ve been working diligently on a DIY Scanning-Tunneling Microscope (STM).

The device I’m building will be significantly cheaper than the $15k a student level machine would cost, and will hopefully reach that range of performance.  I’m certainly not expecting to build a device that can have the accuracy to do real research for only a few hundred dollars, but I’m hopeful that we can achieve modest results.

Right now, I’m basing the design on the work of John Alexander, but we (my electrical engineering and software gurus and I) will be extending and improving this design for microprocessor control and trace capture.  I’m also contacting some of the recent builders of this class of device to hear their opinions and advice. I really am standing on the shoulders of giants here, and by basing my work on that of a lot of (very) brilliant people, I hope to be able to achieve success.

[Project goals, current, and future state after the jump...]

My intention is to release all hardware designs as open source once the device reaches a fairly stable beta stage of completion.

Current state:

  • I have a decent board design for the main amplifier and feedback board that I created in Eagle and just received from China and recently soldered together
  • I have completed the microscope’s head board (amplifies the tunneling current and sends back to the main board.
  • I have received all the supplies necessary for manufacturing and mounting STM tips, and I have a little highly oriented pyrolytic graphite sample to look at.

Current steps:

We are deciding on digital to analog and analog to digital conversion designs that will allow the microprocessor board (we’re shooting for using an arduino as the microprocessor) to interface with the feedback/amplification board.

Next steps:

  • Build and test the alpha version of the device.
  • Write microprocessor software.
  • Write interface software.

Feel free to follow along with progress of this project via the STM category.

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4 Responses to “Project Announcement: Design/Build of an STM”

  1. James says:

    Good work! I am looking forward to see how this develops.

  2. Sacha says:

    Thanks – right now, we’re in the process of designing the Digital/Analog and Analog/Digital interface (nearly done). I’ll have more to talk about when that part is complete…

  3. Steve says:

    Excellent work. I was looking into this a couple of months ago. You are taking the exact same route that I was planning. Have you figured out how you are going to render the picture yet? I was looking at GXSM or Gwyddion, but was not satisfied with either. (Mostly because I lack direct experience with them). The other issue that I ran into was tips that were affordable that could provide atomic resolution. Do you have any thoughts that you can share?

    Again, Excellent work. I am looking forward to seeing what you come up with!

    Steve

    • Sacha says:

      Hi Steve,
      Right now, my python code is just outputting CSV data of X,Y,Z coordinates. I intend to switch to TIFF (it turns out that TIFF is uniquely well suited for this kind of thing) and then any image processing software should be able to handle that output (I’ve also talked to the Gwyddion team to promote integration between this project and theirs). Also, I had not heard of the GXSM project until just now – thanks!

      For tips, I’m planning on starting out with chemically etched tungsten tips. They’re somewhat affordable – I think they’re in the $2 per tip range, and they have been used for atomic resolution scans.

      Also, I don’t really expect that I’ll get atomic resolution here (I’m hoping for it of course) – I’m using very cheap equipment at atmospheric conditions – most atomic resolution STM scans happen at a vacuum, if only as a way to remove water from the surface.

      Thanks again!
      Sacha