[TriEmbed] Join us July 1st to learn about a new Scanning tunneling microscope project

[Pete Soper]

Folks,

    Nick Edgington started a project with the Forge Initiative to build 
an affordable scanning tunneling microscope ("STM") capable of 
visualizing individual atoms. He,  Jaime Johnsen, and I have been 
gathering up information and doing a few initial things to test the 
waters with input from Rob Mackey of the Forge and others.  Now we'd 
like to start organizing the project and connecting with folks 
interested in becoming involved.

    An STM is a primarily electronic device that senses quantum 
tunneling current flows between individual atoms while an electrically 
charged, atomically sharp probe moves at very close range across the 
surface to be scanned. Commercial STMs such as at universities are very 
expensive. Our goal is to make something that can be reproduced for a 
few hundred dollars. Ultimately we want a kit suitable for school 
children. More details of STM operation here: 
https://my.eng.utah.edu/~lzang/images/Lecture_6_STM.pdf

   Here are some key features of the project:

  * Extremely efficient resistance to vibration. Because the probe must
    move less  than a nanometer from the surface to be scanned, very
    efficient dampening must be used. Also the dampening must be
    portable and use inexpensive materials.
  * A means of moving the probe very precisely. Piezo crystals and
    precise applied voltages are the common method for hobby STMs.
  * A means of creating atomically sharp probe wires (the tip must be a
    single atom!). This typically involves electrochemical etching with
    gizmos to manage the process in a very repeatable manner.
    Alternatively, a probe tip can be made in a much simpler way with
    manual techniques for cutting the probe wire.
  * A very stable package for the probe that contains the piezo probe
    actuator and the probe current front end electronics. One of the
    best projects we've found uses what appears to be a CNC-machined
    block of aluminum that is a thing of beauty just asking to be used
    for inspiration.
  * High performance but inexpensive electronics to sense probe current
    (*peak* current is a nanoampere or two) and digitize it, arrange
    bias voltages between tip and target to enable quantum tunneling,
    and move the probe on three axes. The power supplies have to be
    excellent. Custom PC boards are a given.
  * Software to control the system, gather data and translate it into
    visualization and provide a user interface. A large body of code for
    the Espressif ESP32 (project Edger) can be leveraged for a very low
    cost system. The software will probably be a mixture of Python, C,
    and Javascript.
  * Making test systems that help detect things going right and wrong.
  * Many supporting tasks to do with documentation, safety,
    communication, coordination, sponsorship, etc.

*An informal meeting will be held this Monday July 1st at 7pm *with 
Jitsi using the usual TriEmbed URL : https://meet.jit.si/TriEmbed .

*A more formal meeting will be held in mid August* in a room provided by 
the town of Apex (the Forge is based in Apex).

   The various subsystems of an STM really push the envelope for 
performance, and this project will be quite challenging, even though 
there are many shoulders to stand on.

   A Discord channel on the Edger project is accumulating records while 
we finish setting up a GitHub repository and supporting web resources. 
I'll send directions on how to hook up with it later.

Pete
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