If we want bionic limbs that actually work, we might need smarter amputations

Prosthetic limbs are advancing in leaps and bounds. But as futuristic as these bionic limbs are, users often prefer simpler devices because the fancy ones are hard to control and they don't provide enough feedback. If you flex your wrist, even if your eyes are closed, you can feel where your wrist is and how fast you're flexing it. And if you're holding a barbell, you can feel how heavy it is. Someone with an artificial wrist can't feel any of that--instead, she has to constantly keep an eye on her prosthetic to see what it's doing.