Love the electropen! Copying the idea here but trying to make it even easier: just open up a stove lighter, free up the ends of the two wires, throw away the nozzle (and the safety) and close the handle back up, trigger mechanism still intact. This should work, right? The gas tank is still in there, but it is irrelevant.
Wondering if there are different makes of stove lighters, with piezos that vary in voltage? This one is a Scripto. We tried to measure, using an ordinary voltmeter and an oscilloscope, and get readings that are only about a tenth of the peak voltage reported by Byagathvalli et al. Don't know why.
Our aim, by the way, is to zap snail eggs - because these are a million times bigger than E coli, they need only a hundredth of the voltage. What's been found to work best on this sort of cell is a 75ms square pulse of 10-20V. I'm wondering if this would be doable just by wiring up a couple 9V batteries in series, and closing the circuit across the cells for about a tenth of a second? We'll try it!