One of the most amazing forms of wearable technology is the robotic prosthetic limb. This technology promises to restore normal use of hands and legs to those who have lost them due to injury or disease. One of the major challenges, however, is to get signals from remaining muscles to the mechanical extension. Researchers are making great progress using embedded electrodes, but these are invasive and pose threats as sites for infection or other complications. A group of scientists at the University of St. Andrews in Scotland have hit upon a different approach.

They have created a device that consists of a light source and four light sensors, incorporated into a flexible band that can strap around a subject’s arm or leg. It can sense whether or not a muscle group is relaxed or tense because the muscle tissue changes shape when it contracts. This causes the light to scatter differently, and the change can be detect by the photosensors.

The research team has used the sensor system to control a robotic arm, which could have applications in manufacturing or mining where a human could operate a robot remotely, avoiding potentially dangerous working conditions. It eventually could be applied to controlling prosthetics as well.