http://news.byu.edu/archive13-nov-helmetsmartfoam.aspx
Brigham Young University researchers have developed a “smart foam” helmet lining for immediate, real-time measurements of each hit that a football player endures. The measurements are communicated immediately to a hand-held device, telling coaches if a collision is capable of inducing a concussion, even if the player denies a problem.
“ExoNanoFoam” is a nano-enabled foam that behaves as a piezoelectric in which pressure on the material produces an electrical voltage. A microcontroller sensor in the helmet reads the electrical voltage produced by the foam, and sends a signal to a tablet equipped with a program that interprets it and delivers real-time information on the seriousness of the hit sustained by the player.
As the foam is in contact with the player’s head, it provides a more accurate measurement of the forces on the player’s head than previously used accelerometers. Accelemeters only measure the acceleration or deceleration of the player’s helmet.


http://web.mit.edu/newsoffice/2013/new-implantable-sensor-1103.html
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http://www.nih.gov/news/health/oct2013/nibib-23.htm
http://www.bbc.co.uk/news/science-environment-24571219
http://www.scientificamerican.com/article.cfm?id=could-a-simple-ankle-sensor-help-with-parkinsons-symptoms
http://pubs.acs.org/doi/full/10.1021/nn403550c
http://www.pnas.org/content/early/2013/10/08/1221113110.abstract?sid=35f0c072-fa67-4ec8-9e83-17a292a83982