[anthropisces]

If you look at the literature on the vest, air, rather than CO2 is used to inflate the device. It might be possible to use smaller storage vessels by using another gas.

The work I've done on a free dive vest included a self ditching weight belt. It was necessary to limit the size of the can of gas. We were looking at CO2 and it wasn't capable of inflating a vest at 100' without excessively large cylinders (which equipment-austere freedivers such as myself might abhor).I forget now how we were going to accomplish it, I think it was by evaporating a "fuse" with a AA battery.

Our algorithm worked with a pressure transducer of our own design. It was a simple strain gauge bonded to a metal diaphram. The pressure transducer allowed very complex dive profiles to be evaluated.

I love freediving, but my knowledge of the blackout phenomenon was limited. I have heard that surfacing, or coming close to the surface, and then blacking out is a common occurance. For one scenario, we monitored surface time and "threatened" inflation if inadequate surface intervals were evident. There were warning signals prior to inflation, which would only allow delaying and not completely turning off the device.

It is a complex engineering task and I salute those who are working on it. I would very much like to see them succeed.