By Simon Makin

The word bionic conjures sci-fi visions of people enhanced to superhuman levels. It’s true that engineering advances such as better motors and batteries, together with modern computing, mean that the required mechanical and electronic systems are no longer a barrier to advanced prostheses. But the field has struggled to integrate these powerful machines with the human body.

That’s starting to change. A recent clinical trial tested one new integration technique, which involves surgically reconstructing muscle pairs that give recipients a sense of the position and movement of a bionic limb. Signals from those muscles control robotic joints, so the prosthesis is fully under control of the user’s brain. The system enabled people with below-knee amputations to walk more naturally and better navigate slopes, stairs and obstacles, researchers reported in July in Nature Medicine.

Engineers have typically viewed biology as a fixed limitation to be engineered around, says bioengineer Tyler Clites, who helped develop the technique several years ago while at MIT. “But if we look at the body as part of the system to be engineered in parallel with the machine, the two will be able to interact better.”