I apologize for the lack of information in advance. This is actually an old project, which I am posting at a later date.
Tim Courrejou, and I got together with the goal of exploring the new at the time EMG arduino shield for measuring electrical activity in nerves. I spent about a week printing out the inMoov roboting arm on my 3d printer, and we spent a weekend playing with the EMG shield to see how feasible it would be to control a prosthetic arm using the shield. We modified the arm so the servos were on the outside, to allow room for a wrist inside of the robotic arm.
We were surprised with the level of accuracy of the EMG shield. We were able to isolate individual finger movements, tell the degree to which the finger was retracted, and tell whether the finger was holding in a close position, or relaxed.
We were able to graph the output from the shield. We determined that we would need a lot of the shields to power all 5 fingers, and your arm would be covered in sensors. In the end it wasn't practical to use off the shelf equipment to power the prosthetic arms, however one could be made with enough effort, and a much smaller foot print would be achievable.