Mine are Japanese. :-)
You can find specs on igniters here.
However, to answer your question, the energy in the spark comes from the force of the spring-loaded hammer that hits the piezoelectric ceramic rod in the igniter. The force on the spring comes from the pressure from your finger. You can measure the force and the stroke, and compare that from one igniter to another. Or you can just judge subjectively -- they will most likely be the same within a factor of two.
All of them will have enough energy to light butane. That chemical reaction is on a par with the energy needed for electrophoresis. Neither one requires a lot.
That said, we now must look at the rest of the system -- the cuvette and the solution in it.
The size of the cuvette is huge compared to the actual size required.
We might aim for an efficiency of 10 cells per nanogram of DNA, and use anywhere from 5 to 100 nanograms of DNA in a run. So we need a container big enough to zap 10,000 cells.
Let's use ten times that to make the arithmetic easy. A cube 100 cells wide, tall, and high.
Let's not crowd our critters, let's give each one a cube 10 microns on a side.
Now we have a millimeter cube for our cuvette.
Normal saline solution has a resistivity of 0.20 ohm-meter. Resistivity is convertible to resistance by multiplying by the length and then dividing by the area. Our length is 0.001, and our area is 0.000001,
In trying to find a source for the energy in a piezoelectric spark, I found this reference.
It says they measured 67.61 milliwatts of power. Since power is current squared times resistance,
we have a current in our cuvette of 18 milliamperes. From Ohm's Law, that gives us 3.67 volts.
Does anyone have any data on the currents used in commercial electroporators? Or the wattage delivered to the cuvette? If they use 1,000 volts and a 40,000 ohm cuvette, we get 25 milliamperes of current, which is in the same ballpark as the 18 milliamperes we get from the igniter in our 1 cubic millimeter 'milli-cuvette'. But they use 25 watts, while we use only 67.61 milliwatts.
One source I found uses 200 to 400 volts, in a 0.2 cm cuvette (200 microliters, or 200 times the volume of our 1 microliter 'milli-cuvette'). They seem to quote a resistance of 1000 ohms. They have pulse lengths of 10 to 25 milliseconds. That's a current of 400 milliamperes, and 160 watts (4 joules of energy). Four joules is just a hair under a calorie, so it would raise the temperature of a gram of water by one degree Celsius, or the 0.2 milliliter cuvette by 5 degrees C per pulse.
On Wed, Jul 30, 2014 at 5:04 PM, John Griessen <john@industromatic.com> wrote:
On 07/30/2014 05:15 PM, Simon Quellen Field wrote:Is it good statistically? No Chinese ignitors of a certain physical size will deliver more current?
not so much a concern with piezoelectric igniters. I often test my igniters by making the spark jump from or to my finger.
John
just wondering...
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