The Wounded Soldier Raptor Prosthetic Hand

[Geoff]

There are a number of options for the tendon lines, nylon, fishing line, steel and even titanium braid wire. For the most part these hands are for simple daily tasks. and give a grip strength of around 20-25 pounds.
The main point, being the design it is, the strength is dependent on the users wrist. all power comes from bending the wrist itself, so no matter how strong you make the tendon lines, you still are only going to be pulling the fingers at the same level of power anyway, so no real reason to go overboard.

One benefit of using stronger lines, is however, the reduction is stretch. Cord and nylon, after weeks of use will gat a small amount of memory stretch in them, and need to be tightened a bit. Easy enough to do with a few twists of the 5 screws on the back, but stronger lines do eliminate that need.

Fair enough, I guess you want them to also be fairly adjustable and easily adjustable also.

It's pretty amazing isnt it, you can get a 3D printer, a mindwave bio kit, an arduino... some servos and now someone at home can make their own mind controlled bionic hand.. man who would have thought..