I don't remember all details as it was 3months ago and I was not allowed to take pictures (I even had to sign an agreement saying I'm not allowed to talk about this product until it is released lol) but I remember there was a captor (is it the right word?) that you put on your finger. You cannot move during 30s, just breath and then the mp3 player tells you how stressed you are and advice you to be less stressed. You can transfer data to the PC and analyse them with a specific software (not emodio lol). Of course I can't tell you how it works exactly. I'm not engineer and I suppose they keep that secret.
I'm French^^ *GenerationMP3