Re: [DIYbio] DIY electroporator

On 02/27/2018 10:40 PM, nisha p wrote:
> if it's a normal
> 4mm electroporation cuvette, 100 ul
> On Thursday, February 22, 2018 at 11:00:42 PM UTC+5:30, John Griessen wrote:
>
> On 02/21/2018 10:34 PM, nisha p wrote:
> > can anyone tell me about the minimum resistance on load present during electroporation and how much current will be drawn
> >
> Depends on size, volume.

The cuvettes I have dealt with so far are plastic with embedded aluminum with interior flat planes of aluminum 10mm x 20mm
spaces apart 1mm or 2mm. We shoot for a voltage of 2100V by design across a 1mm gap filled to 10mm high, (half full).
That corresponds to a volume of 100 ul.
The culture shock electroporator is aimed at bacterial cells without the conductivity of normal saline or blood, so our
target resistance has been chosen for empirical e. coli. results in the past: about 30k Ohms for a length o 1/10 the area.
The cuvette we use has A = 10, l = 1 as in the diagram of resistivity below:

https://en.wikipedia.org/wiki/Electrical_resistivity_and_conductivity

so our R = 30k Ohms (arbitrary choice), and our resistivity is rho = RA/l = (30k)(10)/1 = 300k Ohm-meters.

The 300k Ohm-meters will apply to any shape of cuvette, and any fill level. That resistivity can be zapped
by the culture shock without pulling down the voltage below efficacious levels, (e.g. below 2100V @ 1mm gap for e. coli.).

What resistivity of cell suspension do you want to zap?

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