open source BLM amplifier

[David Gall]

I just discovered BossLab on the web. We have recently published a paper where we provide a basic experimental protocol allowing university undergraduate students to build artificial cell membranes and examine ionic channels properties at the single-molecule level. In this framework, we have developed an open-source lipid bilayer amplifier, the OpenPicoAmp, which is appropriate for use in introductory courses in biophysics or neurosciences. We think that it may be interesting for your community. The corresponding article has been published in PLOSone and can be found here :

http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0108097
 

or on ArXiv

http://arxiv.org/abs/1403.7439

Do not hesitate to contacte me if you need additional information.

[Nathan McCorkle]

On Tue, Dec 16, 2014 at 2:55 AM, David Gall <dgall...@gmail.com> wrote:
> I just discovered BossLab on the web. We have recently published a paper
> where we provide a basic experimental protocol allowing university
> undergraduate students to build artificial cell membranes and examine ionic
> channels properties at the single-molecule level. In this framework, we have
> developed an open-source lipid bilayer amplifier, the OpenPicoAmp, which is
> appropriate for use in introductory courses in biophysics or neurosciences.
> We think that it may be interesting for your community. The corresponding
> article has been published in PLOSone and can be found here :
>
> http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0108097

Thanks David! I've seen the TL071 before, but haven't played with the
chip, nice to see a design out there with some results. I've been
reading up on pico and femtoamp sensors, so this is a great experiment
to find in the same scale of signals!

Looking up Gramicidin A, it seems there are a few suppliers selling
1mg for about $40, and Sigma selling 100mg for $318. Some of us have
it harder than others to order from companies like Sigma especially,
but even some of the smaller companies can be annoying to deal with. A
quick Google search shows Polysporin Pink Eye drops to contain at
least Gramacidin... do you think these would work for a quick and
dirty signal to noise comparison... an even cheaper and more
accessible baseline/standard?

http://www.polysporin.ca/products/antibiotic-eye-drops

Ingredients :
Medicinal Ingredients (per mL) : 10,000 units Polymyxin B (as
Sulfate), 0.025 mg Gramicidin.

Non-medicinal Ingredients (alphabetically) : alcohol, benzalkonium
chloride, poloxamer, propylene glycol, water.


I would like to upload the electronic and protocol files to github,
and convert the board to KiCad. Is this acceptable to you? Do you want
to do it first, then I can do the KiCad conversion and either fork
your repo or send a pull-request for you to bring in the KiCad files?


Also I've been planning to use these for a fast sampler (up to 80MSPS):
http://www.embeddedartists.com/products/lpcxpresso/lpclink2.php
though it would need some level-shifting and some firm/software
tweaks, the LabTool codebase uses that board, and is open... so
tweaking shouldn't be too terrible:
https://github.com/embeddedartists/labtool


In the case of the OpenPicoAmp though, I bet this one-chip solution
would be a great and easy improvement to get bode plots or
freq-response:
http://www.analog.com/en/digital-to-analog-converters/direct-digital-synthesis-dds/ad5933/products/product.html

"
The AD5933 is a high precision impedance converter system solution
that combines an on-board frequency generator with a 12-bit, 1 MSPS,
analog-to-digital converter (ADC). The frequency generator allows an
external complex impedance to be excited with a known frequency. The
response signal from the impedance is sampled by the on-board ADC and
a discrete Fourier transform (DFT) is processed by an on-board DSP
engine. The DFT algorithm returns a real (R) and imaginary (I)
data-word at each output frequency.
"


Thanks again!
-Nathan

[David Gall]

> A quick Google search shows Polysporin Pink Eye drops to contain at least Gramacidin... do you think these would work for a quick and dirty signal to noise comparison... an even cheaper and more accessible baseline/standard?

To be able to resolve single channel openings, you need a tight control on the quantity of molecules inserted in the lipid bilayer (final concentration should be in the pM range). By using a solution like the one you mention, you probably won't be able to obtain such precise conditions. In addition, the other chemicals present in the solution may perturb the bilayer formation. So I would advice to find a source of rather pure gramicidin A (and you actually very little of it and its pretty stable for years)

> I would like to upload the electronic and protocol files to github and convert the board to KiCad. Is this acceptable to you?

This is open hardware project so, of course, the answer is yes. The electronics design is licensed under a Creative Commons Attribution Share-Alike license, which allows for both personal and commercial derivative works, as long as the original paper is credited and the derivative designs are released under the same license.