[Open_electroporator] switching PS parts

[Nathan McCorkle]

On Mon, Nov 4, 2013 at 9:59 AM, John Griessen <john at industromatic.com> wrote:
> On 11/04/2013 11:51 AM, Nathan McCorkle wrote:
>>
>> Could we accomplish similarly shaped pulses with a boost converter?
>
>
> Possibly.  You're just saying, "Can we specify it to a different
> manufacturer?".
>

Hmm, I well I ask that because the circuits look different, the boost
has an inductor, but your's has two inductors coupled (transformer),
so it's not working on the 'inductuive kick-back' right (or is it but
it's only apparent on the high side of the transformer)?

> Depends on voltage.  There's too many variables.
>
> 1st is reduce volts needed by physically thinner cuvette,

Electroporation cuvettes come in standard sizes of 0.2 and 0.1cm
spacing electrode-to-electrode spacing. The 0.1cm version is just big
enough to allow a pipette tip in between to suck up all the GMO
goodness after the pulse.

I'm not sure what kind of metal they use for their electrodes, but I
know its not copper. I think we should get a device working with
standard cuvettes, then since we need to create the cuvette for
lower-voltage designs, we can have a working reference.

> determine what works pulse shape-wise, (meaning a general purpose machine to
> test with,
> made from whatever, but instrumented.  Then you can specify voltage needed,
> etc.



>
> "Boost converter" to what voltage?

For electrophoresis I was looking at around 8kV, based on some DNA
sequencing channel lengths. For electroporation I was looking at
1.8kV. I will try digging up the common resistivities, but you found
some previously except they were reciprocals (conductance) and didn't
mention which values gave the best results (I'll check the Grenier
paper):
"
In order to vary the medium conductivity, small quantities of table
salt were added to samples of de-ionized
water to produce samples with conductivities ranging from 0.7 mS/m to
1000 mS/m. When these
samples are placed into the cuvette, the equivalent resistances that
were calculated. using (2.5) ranged
between 10 Ohm and 15 Ohm. The capacitance of the load is independent
of the medium conductivity and
is calculated using (2.6) to be 35 pF
"

Unfortunately he doesn't have any data for conductivity vs number of
transformants produced. I'll try to find the resistance of common
electroporation buffer or cell suspension... I feel like it's pretty
high. I've always heard you want to limit conduction through the
cells.
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