I came across this video article about an air-bag for cyclists that was shown at the CES tech expo in Las Vegas.
It's a high visibility vest that contains a large CO2 bottle. Sensors detect an immanent impact and inflate the vest. Motorcyclists have had this kind of technology for a while, but the vests are heavy and tend to work by detecting when the rider and bike separate - rather annoying if you forget to disconnect it before stepping off. Apparently equestrians can adopt this kind of protection too.
There's a better video link at https://www.youtube.com/watch?v=vU1oeYIeRYQ that gives more detail. There's a link to the Helite B'Safe website here https://cyclist.helite.com/
You attach a sensor to the seat post that detects high G-force events and triggers the vest remotely. In the video, the rider falls off the bike rather sedately so I'm surprised the vest triggered. The device only works if the vest's zipper is closed, which is inconvenient when it's 100 degrees outside.
After being triggered, the vest can be re-used by replacing the CO2 cartridge. It looks like the same 16 gm cartridge that brewers use, but they don't actually specify the size on their website. The product is French so who knows if you can get the CO2 in the States.
I have to say that, overall, this is a very interesting product.