New ways to connect wires to nerves are enabling devices that plug into the network of nerves that normally relay commands from the spinal cord to the muscles, but fall silent when a spinal injury breaks the chain.

To achieve a better connection, Case Western Reserve University researchers developed the flat interface nerve electrode (FINE): a cuff squashes a nerve flat to bring fiber bundles closer to the surface and to the eight electrodes in the device’s soft rubber lining.

Neurostep, from Neurostream Technologies in Quebec, Canada uses the FINE technology to control ankle movement for people with foot-drop, a condition in which nerve damage makes one foot hang limply while stepping forward. It also reads signals sent back by the foot to communicate the pressure it feels. A control unit implanted in the thigh uses that pressure information to time its signal to flex the ankle in a way that achieves a normal gait.

University of Utah bioengineer Greg Clark is testing a device called the “Utah slanted array” with up to 100 wires designed to be gently pushed into a nerve. The result is the most precise control yet of any of the limb-activating devices, he says. It has allowed previously paralyzed cats to stand, and has been used to control the movement of a monkey’s fingers individually.