I'd recommend getting in touch with motorcycle helmet manufacturers (particularly MotoGP and WSBK sponsors) because concussions are a huge issue in motorcycle racing. As your site states, concussion severity is very abstractly diagnosed without data, and your product can make a big difference. The doctor has a tough time deciding whether the athlete is fit to race if he's had a crash and a concussion, and it ultimately comes down to a qualitative decision made by the rider and doctor. Data can definitely help save lives here.
If I have time for the track this season, I'll definitely sign up as a tester. I've never had a concussion, but I sure as hell would want to know how fast my head decelerates after a crash before getting back on the bike.
Good luck, and cheers on a great idea.