1) First defib type shock that saved a life took place all the way back in the 1940's and used metal spoons!
2) The biphasic tech allows for significantly less shock (joules) to be used in treatment do to the waveform.
3) The lower-level of required shock is what has allowed for the size of AEDs to shrink.
4) Multiple biphasic waveforms exist and are used by different manufacturers (per this article),
I was really amazed at how far the technology has come over the last 60+ years, but at the same time not when comparing the advancements in other areas of medicine and general life (internet, airplanes, etc.). I just thought the article was worth sharing for those interested in understanding a bit more of the technology behind the defibrillators we see and purchase these days. If nothing else, some of the facts are quite surprising :).