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<p>The meeting is 7pm via a zoom-like thing in your browser here: <a
class="moz-txt-link-freetext"
href="https://meet.jit.si/TriEmbed">https://meet.jit.si/TriEmbed</a></p>
<p>The Discord server mentioned earlier can be joined here:</p>
<p><a href="https://discord.gg/7NUxwzKc"
class="moz-txt-link-freetext">https://discord.gg/7NUxwzKc</a></p>
<p>(Discord is not being used directly for the meeting)<br>
</p>
<div class="moz-cite-prefix">On 6/27/24 20:49, Pete Soper wrote:<br>
</div>
<blockquote type="cite"
cite="mid:d34b916f-4843-4079-a888-d9ead56b6431@soper.us">
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<p>Folks,</p>
<p> 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.<br>
</p>
<p> 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: <a
href="https://my.eng.utah.edu/~lzang/images/Lecture_6_STM.pdf"
class="moz-txt-link-freetext" moz-do-not-send="true">https://my.eng.utah.edu/~lzang/images/Lecture_6_STM.pdf</a><br>
</p>
<p> Here are some key features of the project:</p>
<ul>
<li>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.</li>
<li>A means of moving the probe very precisely. Piezo crystals
and precise applied voltages are the common method for hobby
STMs.<br>
</li>
<li>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.<br>
</li>
<li>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.<br>
</li>
<li>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.<br>
</li>
<li>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.</li>
<li>Making test systems that help detect things going right and
wrong.<br>
</li>
<li>Many supporting tasks to do with documentation, safety,
communication, coordination, sponsorship, etc.<br>
</li>
</ul>
<p> <b> An informal meeting will be held this Monday July 1st at
7pm </b>with Jitsi using the usual TriEmbed URL : <a
class="moz-txt-link-freetext"
href="https://meet.jit.si/TriEmbed" moz-do-not-send="true">https://meet.jit.si/TriEmbed</a>
.</p>
<p><b>A more formal meeting will be held in mid August</b> in a
room provided by the town of Apex (the Forge is based in Apex).<br>
</p>
<p> 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.<br>
</p>
<p> 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.</p>
<p>Pete<br>
</p>
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