The First type of Prosthetic arm they talk about one of our mentor's has. He was electrocuted while working (I believe at GM) when he was in his 40's and his arm was amputated. An electric Current when up his leg and exited through his arm and it was completely fried.
http://sabrerobotics.com/team_view
If you scroll down you can see him (Chris Miles) holding up his prosthetic arm.
He has been an amazing mentor and teaches us everything he knows, shows us how do do things easier, and how to make decisions. He looks scary, but is probably one of the best mentor's i have had.