I think this is a really cool idea. Insoles are a concept that are already familiar to many people who experience falls and to seniors, and it sounds like an idea that seniors might find acceptable for use, without forcing them to change their ways too much!
I wanted to follow the thread that Anne-Laure Fayard picked up about the type of data collected. It sounds like you have given thought to how medical teams might wear this information. I wonder what data the person wearing the product would want and would benefit from knowing (the two may not be the same, I realize) and how frequently providing data to the user might be helpful. I'm thinking that giving feedback to the person wearing this insole could be useful too. It might give them information that they didn't know about themselves, how they walk, places where they tend to be tipsier than others, etc., and could be useful as an ongoing reminder to tread carefully!