Hi all, i'm new to Arduino and I have some questions for you. 
I play Taekwondo and after many researches, I need advices for my project.
I would like to know how electronics chest protectors works, I read on forums they are made of piezoelectrics sensors.
So my first question is, which kind of piezoelectrics sensors ? Ceramics, Velostat ?
Which choice would works best ? I want to detect a foot impact on the chest protector and mesure approximatively the force of it.
How many piezo elements I need to cover the whole surface of the hogu ?
PS : Sorry for my English, I do my best. 