Capillary electrophoresis that I made but can be improved

[Gordana Ostojic]

Here is a capillary electrophoresis setup that I made http://www.instructables.com/id/Capillary-Electrophoresis/ . Ultimately I think it can be used as a replacement for gel electrophoresis for bio DIY but I am not going to able to work on it next 2 months so I kinda wanted to just update you people, in case someone wants to take their own take on it. Also I think some parts can be used for standard gel electrophoresis (using syringe needles instead of platinum electrodes could possibly work even though higher current in GE could be the culprit). 

[Nathan McCorkle]

Nice! So it seems you never tried it with DNA? From what I can
remember, mass-to-charge is constant regardless of DNA length, thus
you need activated capillary walls to aid effect separation.
(easiest to read reference on internal coatings for DNA
sequencing/separations I could quickly find is pg 130 here:
https://www3.appliedbiosystems.com/cms/groups/mcb_support/documents/generaldocuments/cms_041003.pdf)

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[Gordana Ostojic]

I was trying something along the paper attached bellow but it was very finicky since I didn't have correct buffer and my pvp is lower MW. It should work as they showed in that paper but I need more time to nail it down (also order correct buffers). Since I am going away for next 2 months, I just wanted to share what I had till now just in case someone else wants to do their own stuff. The whole capacitive sensing is very powerful, and simple enough in my opinion so I just wanted to share.

[Nathan McCorkle]

On Fri, Jun 17, 2016 at 5:18 PM, Gordana Ostojic
<gordana....@gmail.com> wrote:
> I was trying something along the paper attached bellow

Thanks, I'll check it out!

> The whole capacitive sensing is very powerful, and simple
> enough in my opinion so I just wanted to share.

I agree, I've been wanting to play with this chip for a while for
similar purposes, though it is more of an all-in-one chip (has the
signal generator, ADC, etc... you just talk digital serial to it).

http://www.analog.com/media/en/technical-documentation/data-sheets/AD5933.pdf
AD5933

[Gordana Ostojic]

That looks like a beast of a chip. I didn't have a clue that they can do all that stuff in single chip (DFT, freq. sweep). Please let me know if you get to use it. Cheers!

[Markos]

Hi Gordana,

Very interesting your project.

I was curious to know more about the source of high voltage.

In the past, I thought to mount a capillary electrophoresis, but I confess I gave up because I was afraid of working with a high-voltage source.

I've seen capillary electrophoresis projects that used a high-voltage source removed from CRT monitor (flyback).

The HV source you used stores any charge when turned off?

Could you provide more details about how you identified the input and output polarity of the power supply?

You put the source in a Faraday cage to protect the detection circuit from interference or to protect the user?

Congratulations.

Best Regards,
Markos

Em 17-06-2016 18:24, Gordana Ostojic escreveu:

Here is a capillary electrophoresis setup that I made http://www.instructables.com/id/Capillary-Electrophoresis/ . Ultimately I think it can be used as a replacement for gel electrophoresis for bio DIY but I am not going to able to work on it next 2 months so I kinda wanted to just update you people, in case someone wants to take their own take on it. Also I think some parts can be used for standard gel electrophoresis (using syringe needles instead of platinum electrodes could possibly work even though higher current in GE could be the culprit). 

[Boštjan Vihar]

Awesome project! I will try to rebuild it in the summer and will give you feedback on how it goes...

Dne petek, 17. junij 2016 20.24.36 UTC+2 je oseba Gordana Ostojic napisala:

[Gordana Ostojic]

Hi Markos,

I initially started with this HV - 2KV and that one discharges slowly. I got myself shocked couple of times before I made a parallel connection with a switch and a light bulb to discharge it. I thought that one can put in-line fuse with some limiting current to prevent large current going through you or equipment, or in my case I used batteries to supply input voltage (that limits how much energy it can discharge so I felt safer). Also, you can discharge it by touching electrodes but it does produces awful spark and it is not good in the long term for electrodes or circuits around. 

After I burned this one (left the discharge circuit on while it was working so the transistor on the board overheated), I got the HV -7 and 20 KV.    These are step up type (not sure about the previous one) and I think they should be good for CE since one does not require lots of current. They are also safer since overall energy is small. These discharge fast so I removed parallel discharge circuit. 

Regarding the measurements of polarity and voltage, they all have labeled input (red for +) and white for -, and output I checked with 15 1MOhms resistors and 0.2 MOhms  in series, and measured voltage on 200 KOhm  to check the polarity of electrodes. 

Faraday cage is to protect external electronics from the electric field. Detection circuit will register hand waving above it so that should also be Faraday cage-d but I just stay away during the measurements. If you are afraid of HV I suggest to buy smaller voltage one and play a bit. 

Cheers!  

[Gordana Ostojic]

Thanks Bostjan! Please ask here or you can email me if you need anything.

[Boštjan Vihar]

Will do, thanks!

Dne ponedeljek, 20. junij 2016 19.02.29 UTC+2 je oseba Gordana Ostojic napisala:

[John Griessen]

On 06/20/2016 11:59 AM, Gordana Ostojic wrote:
> I initially started with this HV - 2KV

> <http://www.ebay.com/itm/High-Voltage-Power-Supply-Arduino-HV-Adjustable-DC-2200V-Over-2kV-/252367544293?hash=item3ac2471fe5:g:2UkAAOSwjVVVvRse> and

> that one discharges slowly. I got myself shocked couple of times before I made a parallel connection with a switch and a light
> bulb to discharge it. I thought that one can put in-line fuse with some limiting current to prevent large current going through
> you or equipment, or in my case I used batteries to supply input voltage (that limits how much energy it can discharge so I felt
> safer). Also, you can discharge it by touching electrodes but it does produces awful spark and it is not good in the long term for
> electrodes or circuits around.

In reverse engineering laser printer HV supplies for the electroporator project, I have seen they use commodity
HV resistors of extremely high values as bleeder resistors so the volts goes down rather quickly and also allows swift charge up.
They are through hole parts with a long slab of silica or alumina and two terminals with values such as 200megohm, 400 megohm
1.2 gigohms. Those values are higher than a bare board after you touch it with a sweaty finger and it dries out...
Just for bleeding off charge for safety purposes. In the photo, they are the blue flat rectangles and the yellow larger flat
rectangle.

[Markos]

Hi Gordana,

Thank you for your comments.

I feel more encouraged to start thinking about a capillary electrophoresis for analysis of water quality.

Best Regards,
Markos

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[Gordana Ostojic]

No problem Markos, let me know if you need help. Also, I can check papers that I have, and email you the papers with CE water analysis. Just give me a week or two (I will be travelling). 

Best,

Gordana

[Mac Cowell]

Hi all,

Just met Mike from http://tinkerhack.com at a Manylabs.org open house, he happened to mention air car ozone generators are a cheap source of HV supplies.

Hopefully he will chime in here.

Mac

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