Need advice for building "homemade" electroporator device

[brightfield]

An electroporator is used to pulse cells/tissues with current, which enables DNA to transport across cell membranes - enabling exogenous protein expression.

Basically, the electroporator performs two functions:

1) Apply variable square-wave pulse: a typical example for my purposes would be 5V amplitude, 40 ms t_on, 900 ms t_off, N=4 pulses, ~100 mA

2) Measure current sourced.

Commercially, the electroporator we use costs between $13-15,000. I have never used LabView but it seems to me that this would be a perfect time to start. Basically, I need a function generator that can source enough current, and a way to measure the current that is generated. Ideally, this would be done from the same card using only a single pair of leads. So, can anyone here recommend me some part numbers and LabView software that I can use to make a "homemade" electroporator? One board that seems interesting in this regard is the new PXI-4130, which appears to be able to generate voltage and current in the right range. My questions are whether a) the voltage can be modulated as mentioned above and b) the card can measure the current that is sourced. If this card could do both things, then I could use LabView to generate a signal, send it to the PXI-4130, and measure the current simultaneously. This would be a lot less costly than the commercial system. I would greatly appreciate the advice/suggestions. Thanks.

Message Edited by brightfield on 02-27-2008 04:03 PM

[tnek]

Hi brightfield,

The PXI-4130 will be able to do everything you mentioned. One thing to note is that the voltage changes will be software timed so it will be dependent on your particular system. If you need additional specifications, they can be found here.

An example of how to use a programmable power supply to generate functions can be found here. This can also be done by using an array of voltage setpoints and then associating a wait time for each setpoint to define your duty cycle. Another example of how to use a power supply to measure resistance can be found here. Note: These examples require LabVIEW to view, however there is good background information about how they function on the linked pages.

Regards,

Kent

Applications Engineer

Message Edited by tnek on 02-28-2008 05:26 PM

[JasonWhite]

brightfield,

I do have one question regarding the timing on your pulses.  You mentioned that you needed 40ms t_on and 900ms t_off.  As Kent mentioned, the PXI-4130 can do that via software timing although it will be dependent on how much tolerance you can afford.  For example, you need 40ms +/- how much?  You can probably get about .3-.4 ms resolution on that timing best case.

Jason

[brightfield]

Thanks, for the question. Timing is an issue, but probably 10% (3-4ms) error would not be too bad. It turns out I found another commercial electroporator that runs about $3000, so I will probably go with that for now. However, I am still interested in the PXI-4130, because it would allow us to specify current. All commercial electroporators specify voltage pulses, not current. However, because the tissue resistance varies, I think it may actually be more advantageous to specify current. In general, it is the current that damages cells/tissues, so if we could control the current, it might make for safer/more effective experiments. I hope to try this approach in the future. Thanks, for all the helpful replies.

[A.C.E.]

Hello, this post is fairly recent so I thought I would chime in and ask how the results turned out with the software timing using the PXI-4130. 

I have a customer who is using LV 7.1 and wants to take measurements with a ~1ms accuracy using a 4-wire measurement on the PXI-4130.  I'm running the software at what I believe to be the fastest send rate possible (based on the dev zone article for the 4130) and when trying to measure pulse response am not getting the resolution I'm looking for.  There's probably a good reason for this but a second/third opinion is always nice to have.  For example, if I set a current pulse ON time of 1ms followed by an OFF time of 3s and measure the ON time, sometimes I get 0.000 and sometimes I get 0.0010s for the duration of the ON pulse.  I can't seem to measure more precisely than the ms level in 7.1; perhaps this is the software limitation.  An example of the block diagram is attached.  I'm using a 2527 multiplexer to open/close the current sent to the desired channel.

I'm trying to be as efficient as possible with the timing by (1) sending current to the desired channel with the 4130 DC Power VIs, (2) making the connection with the channel using the 2527 NI-Switch, (3) waiting the desired amount of time using the time delay, (4) measuring the voltage right after the time has expired, and (5) opening the channel switch to drop the current to 0mA.  If I stick a timing measurement into the loop shown in the attached (it's not present now), I either measure 0ms or 10ms as a loop time if I set the pulse width to be anything less than 10ms.  Customer wants to take a voltage measurement (DC Power) within 1ms of the change in current level. 

The 4130 can update 4-wire at I think a minimum of 667 microseconds with everything optimized, but what is the best way to measure this???

Thanks!

Alex

[tnek]

Hi Alex,

The best way to measure how long a current operation takes to run would be to do your own benchmarks. Run the operation a number of times and take the time before and after all the iterations of the operation. The overall time can then be divided by the number of times the operation ran to give an average time per operation. Some examples can be found with other benchmarks that NI provides. Here is a link with a few examples of such benchmarks with the VIs used. Let me know if this is what you were looking for.

Regards,
Kent
Applications Engineer

[A.C.E.]

Kent,

Thanks for the feedback - I'll give it a whirl.  I was trying to confirm timing response with each pulse, but the benchmarking may certainly produce enough data to allow one to '"assume" that the timing is appropriately fast.  Thanks again,

Alex

[maviris]

This post is very old, but thought I'd give it a try. 

I have a similar application (8 x 25 V 50 msec on, 100 msec off) and was wondering what low-cost electroporator you purchased and how it has worked for you - or have you built your own with the NI board? 

Thanks!