This project is no longer active

Hello and thanks for visiting!

Unfortunately, you’re looking at an archive of projects I worked on and/or completed.  I’m leaving this all up for now for historical purposes, but if you want to see the latest things I’m working on, Chemhacker isn’t the best place any more.

There are a lot of reasons for the change, but the biggest two are:

1) “Chemhacker” doesn’t really describe me.  I work on a lot more things than just chemistry and science, and I found the title to be stifling to blog under.

2) “Chemhacker” kinda came to mean that STM project I stopped working on quite some time ago.  I stopped working on it because STMs are really difficult to do well and I found other problems that interested me more, and so I moved elsewhere.

If you’re interested in seeing the things I work on now, here are places where I’m publishing my projects:

Blog  << primary outlet of things I do

Twitter << side outlet, thoughts, what I’m reading, etc




January 29, 2014 | Posted in: Announcement | Comments Closed

Chicago Awesome Foundation is Awesome (and hello Make Magazine-ers)

I was notified late Wednesday that I have been awarded the October 2011 grant from the Chicago Awesome Foundation for completing the full prototype of the Scanning-Tunneling Microscope. Their posting is over here. For the record, yes, I officially love the Awesome Foundation.

At nearly the same time, Make magazine blog posted an old video of me playing with the version 0.1 electronics and then Element 14 posted as well (wow, I’ve come a very long way since then – I need to shoot some new video), bringing in a flood of new folks over the past 48 hours. Hello new folks!

For folks who are new, here’s how things stand:

  • The version 0.1 electronics in the video posted on the Make blog was a poor implementation of a good analog design with a microcontroller slapped to the inputs. I’ve since learned that analog is weird compared to digital, and getting those two worlds to talk properly involves a lot more finesse and art than science and equations (equations do get you into the ballpark, however).
  • I’m nearly done with a complete redesign of the digital and analog electronics (now at version 0.3). The new electronics incorporates nearly complete digital control of the STM (I’m working on ways to further increase the control the microchip has over the STM to include gain control of the many op-amps). Thanks to Idea Petri Dish for the assist on analog circuit design and troubleshooting.
  • With new electronics comes new firmware and software of course, which is in-process.
  • I’ve done a very rough draft of the vibration dampening table design.  I’ll be using a classic floating gravestone style table – a heavy slab of material suspended by rubber bands, surrounded by a support structure. It’s not fancy, but it works.
  • I’m working with Bart Dring, of MakerSlide fame to design the rough approach (basically a screw, direct-driven by a 400 step motor and a 1/16th step driver, like the pololus popular with the RepRap folks).
  • I quit my job to pursue my dream of working in the device design industry, so if you’re feeling particularly generous, please purchase a periodic table – 100% of the proceeds goes towards funding this project.
  • If you want to find out when kits are available (soon, I hope), sign up here.

Your support did this!

To everyone who purchased a periodic table to help support this project:

Many, many thanks!  I can’t easily express how grateful I am for your generous support!  I’ve chosen to quit my job to pursue my passion of open source scientific devices, and your support goes directly towards furthering this project.

I just received the first visible result of your help – a shipment of components.  These are mostly op-amps, voltage regulators (silver bags on the left), capacitors, and piezo disks (clear bags on the right).  This shipment will solve several power supply and signal issues – - the +2.5V signal will actually be +2.5V now, significant improvement over the unreliable voltage divider I was using previously.voltage regulators, op-amps, piezo disks, and capacitors


Would you like to support the Chemhacker STM project?

Chemhacker periodic tableI’ve been asked this question a few times in the past week – how can someone support the Chemhacker STM project?

Here’s the easiest way: purchase a periodic table! I designed them myself, they are accurate to 5 significant figures and even contain Copernicium, the newest element! You can’t do chemistry without a periodic table.

So if you’re having trouble combating sentient grey goo, you should support the Chemhacker STM project by purchasing a periodic table!

$25 and ship worldwide for free.


Please Vote! Open Hardware Scholarship Applicant!

OSHW logoHello everyone,

I’m delighted to announce that I’m an applicant to the Open Hardware Scholarship. It’s a grant of over $2000 for the completion of an open hardware project.  Without going into boring personal finance details, $2000 will allow me to more rapidly push the Open Source Scanning Tunneling Microscope project to the public beta stage.

The scholarship award will be chosen by votes, so please visit the Open Hardware Scholarship voting page (I’m the fifth one down on the left side of the page) in the next 24 hours  (voting ends September 15th 6pm EST) and vote for the project you feel is most deserving of a grant (hopefully this one).

Here is my 30 second application video (no, it’s not easy explaining this project with only 30 seconds and 500 characters):

Many thanks,

Sacha (Chemhacker)


UPDATE 2: thanks so very much for all the votes everyone! Sadly, microscopes lose to hydroponics. Winners list at

UPDATE: fixed the voting link, please go here:





STM Version 0.3 electronics on the way

This is just a quick note: I’m currently breadboarding version 0.3 of the STM electronics – Hopefully I’ll have photos and results shortly thereafter.

New features of this version:

  • 100% of John Alexanders’ analog STM design has been replaced with all-digital controls
  • Greatly simplified electronics (but more complicated firmware)
  • Microcontroller manages four channels: X, Y, Z movement, plus sample bias
  • Teensy microcontroller (though the design is pretty microcontroller-agnostic at this point)
  • Firmware tunneling current detection and PID control of Z height

Thanks to Steve F., and Efrain O. for their extremely valuable input to this revision.


1 year STM project anniversary

It’s now been a year since I first decided to start building an STM in my spare time – this project has taken me all over the country and I’ve learned a huge amount.

I haven’t had much to talk about lately because:

1) I’ve been focusing on hardware upgrades that improve efficiency and speed in not-immediately-obvious ways (look for the teensy at the botom of the picture, and the shiny new chips near it).

2) Since I’m working on signal path stuff, I had a pause while my new DSO nano (at the top of the photo) shipped from overseas.

3) I’ve been completing other projects so I can refocus on the Z signal path with fewer distractions.

Thanks very much to my friends Mitch Altman, Jordan Bunker, Camo, Steve Finklestein, Ian Spielman, and everyone else who took me seriously enough to help me push this project down the road towards reality in 2010!  Here’s to a productive 2011!


v.0.1.5: rebuild and bug fixes

I just finished building the version 0.1.5 machine.

Here’s what I’ve been working on during the past month and a half:


  • Fixed EAGLE routing flaws (thanks Dorkbot Chicago for a very timely EAGLE CAD class!)
  • Fixed part specification flaws (it turns out that the digital pots I originally used can’t handle much more than 8V, I was giving them 18V – oops!)
  • Built a completely new test machine from scratch, by hand (not as bad as I originally feared)
  • Started an arduino shield based design (using adafruit’s excellent protoshield as a starting point)
  • Started testing the MCP4912 DAC as a replacement for the dual 4911s, I’m currently using.
  • Switched from arduino duemilanove to freeduino/boarduino for physical design improvements (I’d like to use the UNO, but I’m waiting/hoping for improvements in the USB functionality of that board before switching).
  • Added a fast prototyping area for experiments.


  • Stopped using magnets as fasteners for the scanning head – those were awful.
  • Built a completely new physical support with improved tripd geometry and stability.

Next up:

  • Redesign the X/Y signal pathway to use the full +/- 9V range and be flexible enough to handle +/- 18V via switch and/or gain adjust (I’m only using +/- 5V now, and it’s not flexible at all).
  • Redesign the transimpedance amp pathway to improve signal/noise ratio and gain.
  • Investigate alternative approach mechanism designs.

Reminder: I’ll be showing the ChemHackerSTM version 0.1.5 at the Armand Hammer Museum in LA on Saturday afternoon/evening as part of CRITTER Salon’s Enormous Microscopic Evening.


Pining for the fjords

HELLLLOOOO POLLY!This project is not dead, it’s just pining for the fjords!

Actually, I’ve been up to my neck in:

  • rebuilding the circuit from scratch
  • debugging software
  • debugging hardware
  • redesigning circuitry

This is all stuff that is slow and relatively unglamorous.

I’ve been working frantically because I’ll be in LA next weekend showing the microscope at the Enormous Microscopic Evening at the Armand Hammer Museum in UCLA on November  6th at 4pm, and I’d really like to have version 0.2 ready for the exhibit.

I’ve learned a lot in the past month – notably that I had made a few poor design assumptions (now thankfully corrected).

Many thanks to everyone for being patient, everyone who has helped me with debugging and redesign, and to CRITTER salon for inviting me to the Enormous Microscopic Evening!