Stairs can be difficult for many elderly and disabled people, and current alternatives such as elevators, stair lifts and escalators are expensive and use a lot of energy.
But there is some good news. Researchers say they've developed stairs that "recycle" a person's energy, which could be of help to seniors and disabled people.
A 'leg up' on the ascent
The stairs use latched springs to store energy when someone goes down them. The energy is then released when a person climbs the stairs again.
People who want a good workout or improve their general stair-climbing abilities should have a look at this video.
According to the researchers from Georgia Institute of Technology and Emory University in Atlanta, the high-tech stairs absorb a person's energy as they descend, which cuts forces on the ankle by 26%.
But when the person then ascends the same stairs, that energy is released, making the stairs spring up a bit. The ascent is therefore 37% easier on the knees than otherwise.
"Unlike normal walking where each heel-strike dissipates energy that can be potentially restored, stair ascent is actually very energy efficient; most energy you put in goes into potential energy to lift you up," said Karen Liu, an associate professor in Georgia Tech's School of Interactive Computing.
A more practical and affordable option
"But then I realised that going downstairs is quite wasteful," she said in a school news release. "You dissipate energy to stop yourself from falling, and I thought it would be great if we could store the energy wasted during descent and return it to the user during ascent."
Liu said she got the idea for the new technology after watching her 72-year-old mother struggle to climb stairs.
To test the machine, Liu's team analysed patterns of energy use while nine volunteers went up and down the stairs.
Further study is needed, but energy-recycling stairs might become a more practical and affordable option, the study authors suggested. The study was published in the journal PLOS ONE.
"Current solutions for people who need help aren't very affordable. Elevators and stair lifts are often impractical to install at home," said Liu. "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."
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