The meeting is 7pm via a zoom-like thing in your browser here:
https://meet.jit.si/TriEmbed
The Discord server mentioned earlier can be joined here:
https://discord.gg/7NUxwzKc
(Discord is not being used directly for the meeting)
On 6/27/24 20:49, Pete Soper wrote:
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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