April Update

It’s been far too long since I’ve posted here, and the more time it was since that last post, the harder it became to post here.

So I’m just going to start again.

Mostly what happened is that I got stuck on some very frustrating bugs with my new hardware design and it took far too long for me to ask for help, so I lost all motivation to work on this project and found other shinier things to play with.

I’m now past that hurdle, and I think I have a way to keep motivation and progress going in the right direction.  I’m going to have a weekly or so meeting where I can ask for help and people can ask me basic questions about my designs, helping me to fix problems as they come up, and readdress all my basic assumptions.

This is basically what most advisers do for their students, keep them on task by asking questions and act as a sounding board for problems.  Maybe that’s something that could/should be used more widely in at-home science arenas?

Another inspiration for me is that ZeFrank came back.  My current favorites are this classic motivation, and this brand new motivation.

 

General updates since my last post:

Electronics:

Following a series of discussions with my analog adviser (hi Steve) and my physics adviser (hi Lee), I’ve started working on version 0.4 of the electronics (now with actual theoretical chance of working!). I received the (painfully small) surface mount parts from DigiKey and Newark, and managed to solder them to SMD-DIP adapters for breadboarding.

Things I learned:

  • Arduino ints only go to 2^15, that is a problem when dealing with 16-bit DACs.
  • My new DAC’s “write” command only means here’s some information, not do something with the information I’m giving you.

Mechanicals:

Bart from BuildLog sent some makerslide, a 400-step stepper motor, and other amazing things as part of his Makership project so I can build a solid linear actuator for the rough approach.

Funding and Support:

Wow, thanks so much to all the amazing people who decided to help this project with funding, parts donations, and their generous time:

Money:

Chicago Awesome Foundation

Individuals: Nikos G., pdp7, T. Joseph N., David C., Bruce G.

Stuff:

Bart from BuildLog.net

Time and advice:

Steve F., Ian S., Lee

image credit

Share

Open Notebook 1

This is an experiment with opening my research notebook to the web.  I’m keeping my notes in an Evernote notebook, but I’m going to post lightly edited (i.e. remove personally identifiable information from people I talk to unless they give me specific permission).

Keep in mind that these are my raw thoughts for the past two months, with no editing for accuracy.  Follow these notes at your own risk.

11/03/2011 (Purchase Notes)
Purchased from Newark ($62.46 + shipping):
* 3 DAC8554 (TSSOP-16 packages)  quad 16 bit DAC
* 3 REF02 (DIP-8 packages) precision 5v reference
Purchased from eCrater user fcpcb ($11.44):
* 5 TSSOP-16 to DIP adapters

10/31/2011 (Denver/Boulder Notes)
met L. M. (physicist) at Solid State Depot hackerspace meeting – he built an STM as part of his PhD work:
* L. M.’s STM had a higher cost (and precision) than the chemhacker STM, but a lot of his designs and thoughts can be adapted to fit a cheaper device. Also, he’s excited by the idea of an open source STM project.
* need more bits on the Z DAC
* * 10 bits gives ~17.59 mV/step which is ~2.81 nm /step (at ~0.16 um/volt) that’s so large that the needle will pass into and out of tunneling in only one step.
* * 16 bits gives ~0.2747 mV/step which is ~43.9 pm/step, small enough that you can control tunneling with more than one step.
* * 16bit DAC notes:
* * * DAC8554 from TI is a 4-channel ultralow glitch DAC
* * * $10-15 each: pricey, but handles all four channels at once, not much more expensive than 4 of the microchip DACs I’m using
* * * SPI interface, unsure if it differs from the microchip SPI standard
* * * TI recommends a REF02 precision 5V voltage reference (~$3-4 each) – probably a good idea to try this out
* * * downside: no DIP package available – surface mount only
* probably need a better/faster micro controller
* * suggest that PID loop be accomplished at about 20MHz
* * suggest the Maple from Leaf Labs
* * * 12 bit ADCs (versus 10 bit for arduino/teensy)!
* * * 47 MHz versus 16MHz for arduino/teensy
* * * the IDE looks almost exactly like the arduino IDE.
* * * I’ve spoken to Leaf Labs folks in the past, they’re a good group of quality-focused engineers/artists.
* * * purchased on 10/30/2011 should arrive in a day or so via USPS
* thoughts on the sample bias voltage
* * since sample needs only ~10 millivolts, it’s probably best to just pass the DAC output through a pair of unity inverting amps (don’t remove the DC bias).
* * then, put the two outputs (positive and negative outputs) to a manual switch so the user can choose a positive or negative sample bias (allows future expansion to negative sample bias)
* * with a 16 bit DAC, it’s pretty easy to select ~10mV (just set DAC to ~4 and leave it there)

10/20/2011 (Nanotech conference notes)
Questions for people who know more about SPM than I:
* Is Gwyddion well-regarded in the microscopy arena?
* How do you make HOPG / graphene? Is it at all easy?
* What is an appropriate sample bias for starting? I saw ~10mV today, but I was going to use ~1-2V, that’s bad.
* Is there a market for STM tip-making machines?
* What is the process for making an AFM tip?

10/19/2011 (prototyping notes)
* added 2.5V and 5V voltage regulators to clean up voltage signals
* fixed clipping problems by lowering the gain resistor from 36k (predicted by the formulae) to 27k (as determined experimentally)
* fixed non-symmetrical behavior by applying correct ground to the 2.5v and 5v regulators (their grounds were floating a little higher than true ground)

10/10/2011 (Purchase Notes)
Purchased from Newark ($43.69)
* +9v, -9v, +5v, +2.5v voltage regulators
* piezo elements
* 0.1uf, 1uf, 0.33uf capacitors
* tunneling op-amps

9/23/2011
CHEN chapter 11.1: desirable tunneling amp design: 1V/1nA

9/10/2011
Idea: change op amp gains such that the electronics use ground, +5v, +12v, -12v >>same as supplied by ATX power supply
Test: test ATX power supply with oscilloscope to check cleanliness of signal (should be pretty clean, right?)

…actually, can use these power supplies now without changing the gains…

Share

ChemHackerSTM 0.1 Schematics and Source Released w/GPL3

With a lot of help, I’ve hit the 0.1 milestone (proof of concept), so it’s time to release version 0.1 of the ChemHackerSTM designs and source code.  As the version number indicates, this is a proof of concept device — if you follow these plans, you’ll get an STM that sort-of works – no promises.

All designs and source code in version 0.1 is hereby released under GPL 3.

The physical microscope is built and works.  It’s still fiddly – I have several design improvements in mind.

The microscope’s electronics work, and will probably not change only moderately between now and version 1.

Video and source code after the jump. Read the rest of this entry »

Share

Laser testing: movement!

I just completed a new (much better) scanning head in preparation for final build and testing, but how do you know if the head is actually moving back and forth?

The answer I came up with is to use reflected laser light to amplify the movement of the scanning head.

To test the new head, I mounted a small mirror (actually a sequin, they’re lighter) in the needle mounting point, shined (shone?) a laser at the mirror to see if I could see movement in the reflected laser point as the scanning head moves back and forth.  What I saw was a little movement, but the laser reflection was so diffuse and the movement was so much smaller than the laser reflection that the movement didn’t show well on the video I shot, so you’re going to have to put up with still photos until I acquire better mirrors and/or a more focused laser.

Laser and sequin

Diffuse, reflected laser light

Share

Insane Clown Lab

I’ve been wanting to upgrade the storage in ChemHacker central for a while – but I haven’t found a good, sturdy storage unit that is large, can handle holding a lot of weight, and is chemically resistant.

Until now.

I found this old Faygo-labeled shelving unit in a nearby alley:

After a (lot of) cleaning, here it is holding tools and a wide assortment of chemicals in the underground ChemHacker Lab:

Now that I have Faygo-themed shelving, perhaps I should look into teaching Juggalos some f’ing Science?

Share

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...] Read the rest of this entry »

Share

Radio Interview with ITFreely: Eating the Elephant

Sacha

Last night, I had the honor of an interview with David Dolphin and Gareth Eason from ITFreely, an Irish radio show on science and technology.  We discussed hackerspaces, my current experiments, and the current state of garage experimentation.

It was a lot of fun, but listening to myself, I really wish I was more erudite and less stuttery – the final question was especially bad on my part – he asked me about the effects of an STM on drug manufacture, and I gave a true, but somewhat lame answer – that an STM really isn’t helpful for making drugs.  Here’s basically what I wish I had said (I came up with this hours later, of course):

The truth is that people like me have much more to fear from society than society has to fear from us basement chemistry tinkerers.

The irrational fear that everyone with a chemistry set is making methamphetamines or bombs has caused a lot of unfounded raids and arrests.  This stifles innovation and experimentation.  Every time I mention that I have a chemistry lab in my house to anyone, that person immediately jokes about drugs or bombs, and that’s a little scary considering my country’s raid first, ask questions later mentality for chemistry.  Hence the tagline I use on my website: Chemistry is Not a Crime.

In my case not only do I not know how to make meth, I honestly have no desire to make pharmaceuticals. Or explosives – both are way too dangerous, not to mention illegal.  Turning $1.50 of household chemicals into $30 worth of nanoparticles sounds more than lucrative enough to me, and it has a much lower legal risk.


IT Freely Season 2, Episode 15: Eating the Elephant

Share

Fail, then Question Everything (Research Notebook)

In my current job, I don’t do research, and I miss it.  This is partially why I started the chemhacker project – it’s a way for me to take some fun chemical projects, research them, develop my own processes for making a few things, and maybe even make some new things.

Over the past few months, I have been slowly working on a process for making ferrofluids by making magnetite nanoparticles, then adding surfactants, and suspending them in a liquid.  Starting only from (mostly) readily available household chemicals.

I started with a process that I know works, but has a lot of problems  – the end product isn’t very good, and there are unnecessarily dangerous intermediate steps, but it works.  I successfully ran through the bad process, listed all the problems I found, and prepared to move onto my new, safer, more efficient, better process.

And then it happened.

Read the rest of this entry »

Share