DIY Electroporator (invitrogen II) - reverse engineered manual/documentation

[cameron]

Folks,

I bought an old Invitrogen Electroporator on Ebay for $65. There wasn't a manual so one of our members reverse engineered it and created a wiki detailing how it works. Graham Widerman also found some flaws in the design so he replaced some of the components. For those who want to build your own electroportator, this is a great document to use. We also built in leads which allows us to hook up an oscilloscope directly to monitor the wave form during electroporations. Find the wiki HERE. This is the only place on the web where information can be found on this electroporator so please share as needed.

Cameron

http://grahamwideman.wikispaces.com/Invitrogen+Electroporator+II

[Nathan McCorkle]

Wow, great info!

I will start absorbing this soon :D

John Griessen, have any time these days?

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[Jonathan Cline]

This is excellent work.  I would have expected " Modification 2 " to be part of the original circuit in a hv supply, surprised that it's not, seems like a good modification.  What's your thoughts on wearing a ground strap on one wrist during use?   HV experiments, definitely one-handed.  But undecided on whether a ground strap would be beneficial.  HV hookup wire might be better for the leads from the power supply.  Perhaps the manual knobs can be eliminated and use switch IC's instead.  It would be good to add photos of the cuvettes for completeness.  You might consider publishing this in BioCoder if you haven't already published somewhere.  As for the protocols it seems like the choice of buffer is almost more of an important consideration for higher yield than the voltage choice or waveform shape, from reading published comparison results.



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[Scott]

As of Dec 14th the url says the following. Maybe you can post the details elsewhere. Cheers, Scott

Subscription Expired

This wiki's subscription has expired. The wiki will be reactivated once one of the wiki organizers renews the wiki's subscription.

[Nathan McCorkle]

Closed source strikes again?

And archive.org didn't get a chance to scrape it... Maybe Bryan did?

[cameron]

Jonathan et al., 

I meant to post this response from the author of the wiki who did all the work on the electroporator but got swamped. Here it is below. Also, I'll either ask him to fix the wiki or post it on The Wet Lab's wiki shortly. I'll advise asap.

Cameron

Use of a ground strap:

In the electronics industry context, a "ground strap" (wrist or ankle strap) has the purpose of draining from the wearer any static charge that might accumulate, thus eliminating the (static) high voltage on the person's body which might otherwise discharge into an easily-damaged electronic component. (It's also used in environments where explosive gas might be present and static electricity sparks would be a problem.)

This kind of strap is not used to protect the wearer when coming in contact with high voltage electricity. Indeed, if it were connected directly to ground, it would greatly _increase_ the chance of harm, as it would provide the path for a current to flow if the user does accidentally contact a high voltage source with a different body extremity.

However, these kinds of ground straps usually incorporate a resistor (say 1 megohm) for exactly that reason -- this still allows the desired function of draining the static charge at an acceptable rate, but limits the current if the wearer accidentally touches an HV source.

One might conceive of a strap that, for a right handed wearer, shorts the right wrist direct to ground with no intervening resistor, on the principle that if the right hand touches a high voltage source, any current entering the hand will be shorted to ground at the wrist, and not enter the rest of the body.

This seems like an unattractive gamble: First, it guarantees a severe shock to the right hand in the relatively common case of the right hand touching HV, regardless of whether any other part of the body is grounded. Second it guarantees a maximally hazardous current across the chest if the user accidentally contacts HV with the _left_ hand (or any other body part). 

Finally, it's intended safety effect would only occur in the case where the right hand contacts HV, _and_ some other body part is accidentally grounded, _and_ the connection of wrist-band to right wrist has a resistance very much lower than the resistance through the interior of the wrist to the rest of the body. This resistance ration would be very variable, and it's quite difficult to maintain a low resistance from skin to an electrode (wrist band) without the use of conductive paste. It's not clear to me that even with paste such a wrist strap would be beneficial, though experiments could be done (and perhaps have been?)

Replacement of switches with ICs:

This would be a convenient development. There are now (ie: since the days of Electroporator II) transistors (not necessarily ICs per se) that can switch voltages (and currents) in this neighborhood. 

However, the utility would not be in simply using transistors to replace switches in the existing circuit that has certain fixed capacitors and resistors. Increased utility would come from making the electroporator output pulse shape (time course) insensitive to the variable resistance of the cuvette, and from enabling a range of different pulse shapes and amplitudes.

This calls for relatively intelligent control of the transistor(s) so as to be able to generate the different voltage pulse shapes and sequences, and using feedback to ensure those pulse shapes (notably amplitude) are delivered regardless of variations in cuvette resistance. 

The challenge: When the needed output voltage is less than the upstream supply voltage, the output transistor has to absorb the difference in voltage and dissipate the corresponding power. This calls for either very high power transistors, or for a very low duty cycle and operating the transistor(s) outside their normal characterized specs. 

So, it's territory worth exploring, but it seems like there are no easy wins.

- Graham 

[cameron]

Wiki is back up.Graham also updated it with the latest modifications. He made some connectors so we can plug an oscilloscope directly in to see the exact wave of the pulse during use.

Cameron

On Thursday, September 10, 2015 at 10:58:49 AM UTC-7, cameron wrote:

[Helene Stern]

Does anyone still have access to the schematic PDF for this? Wikispaces no longer exists, and archive sites obviously don't hold onto downloads... https://web.archive.org/web/20170807201242/http://grahamwideman.wikispaces.com/Invitrogen+Electroporator+II+electronics

Many thanks!

[John Griessen]

On 4/12/19 6:35 AM, Helene Stern wrote:
> Does anyone still have access to the schematic PDF for this? Wikispaces no longer exists

No, but I'd love more beta testers for my culture shock electroporator:
https://github.com/kanzure/culture_shock
https://blog.kitmatic.com/2017/06/28/electroporation-is-now-quick-high-yield-and-commodity-priced/

[Dakota Hamill]

How much are they? In stock?

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[John Griessen]

On 4/12/19 12:38 PM, Dakota Hamill wrote:
> How much are they? In stock?

There were 5 of them at the previous rev. that got zero testing with live bugs, just zapping resistors.
Now only 2 of those are accessible, mine and Nathan McCorkle's. I can make more by hand, but... more off list.

[Nathan McCorkle]

If we could replace the cpu with something like a QFP package then i think we could solder these without a hot plate or reflow oven.

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