On Thursday, May 25, 2017 at 6:35:35 AM UTC-7, wrote:
Discovery Channel's Daily Planet had an item on this yesterday: https://www.youtube.com/watch?v=mzoakbBxm5g.

These devices require some means to detect the difference between a bump and a fall. I cannot see any way of doing that in a practical way. Furthermore to deploy them rapidly enough you need a method of explosive decompression which would in all likelihood be more dangerous than the fall it would be capable of protecting you from.

Again - the problem is not the ABILITY to build something that would work - it's the ability to build something that people can accept and isn't more of a danger than the fall.