Researchers have developed an energy-recycling mechanical staircase they hope will one day help older adults or those who are mobility-impaired. The device uses little power and can be placed on existing staircases to make climbing and descending easier on the knees and ankles.

Scientist Karen Liu collaborated with other engineers at Georgia Tech and Emory University to produce the prototype, which works via a system of springs and pressure sensors. The springs in the stairs compress when someone walks down the stairs, which reduces the impact on the ankle joint by 26 percent. When climbing stairs, the springs give the user a boost by releasing the stored energy, making it 37 percent easier on the knee. The results were published last week and highlighted on the Georgia Tech news site.

“Walking down stairs is like tapping the brakes of your car while revving the engine," said Lena Ting, co-author of the paper and a professor of biomedical engineering at Emory and Georgia Tech. "Your legs use a lot of energy bracing each step to avoid falling too fast. Our stairs store that energy rather than wasting it."

Liu came up the idea when she saw an ankle brace that stored and released energy and wanted to help her 72-year-old-mother who has difficulty climbing steps.

“Current solutions for people who need help aren’t very affordable. Elevators and stair-lifts are often impractical to install at home,” Liu said in a statement. “Low-cost, easily installed assistive stairs could be a way to allow people to retain their ability to use stairs and not move out of their homes.”