Biomechanical engineers have unveiled an unpowered exoskeleton -- a small, light, spring-activated device that fits on the lower leg and reduces the energy cost of walking by around seven percent. Exoskeletons are body suits designed to increase mobility and reduce stress on the back, legs and arms by performing part -- or all -- of the work of the wearer's muscles https://www.rappler.com/science-nature/life-health/241725-paralyzed-man-walks-again-with-brain-controlled-exoskeleton