An exoskeleton that allows amputees to feel like they are “walking with normal legs” has been developed by scientists using battery-powered electric motors.
The robust exoskeleton, which wraps around the waist and leg, was developed by a team of engineers at the University of Utah in Salt Lake City.
It has been designed for above-the-knee amputees and uses battery-powered electric motors and built-in microprocessors to reduce walking effort.
The 5.4-pound chassis is made of carbon-fibre, plastic composites and aluminum and you can walk for miles on every electrical charge, according to its creators.
Those who wore it saw a 15.6 percent drop in their metabolic rate, the team said, the equivalent of taking off a 26-pound backpack while hiking.
They don’t know how much the final device will cost, or when it will be available for general use, but they hope to bring it to market soon.
A above-knee amputation severely reduces the mobility and quality of life of millions, in large part because so much of the leg muscle is removed during surgery.
Ordinary artificial legs do not completely replicate the biomechanical functions of the human leg, but the new exoskeleton improves strength and range of motion.
“As a result of this, although you have the ability to move your hip, your ability to walk is very poor,” said Associate Professor Tommaso Linzi, who led the design team.
“There’s a lack of strength and range of motion, when you lose your leg,” he said.
Above-knee amputees work harder while walking by overusing the muscles of the remaining limbs and healthy limbs to compensate for the lack of energy from the prosthesis.
The goal of Professor Lindsey’s exoskeleton is to provide extra energy until walking becomes normal again, bringing it as close to having normal legs as possible.
The device features a lightweight and efficient electromechanical actuator that is attached to the user’s thigh over the amputation area.
As for the belt around the waist, it contains dedicated electronic systems, in addition to microcontrollers, and sensors that work with advanced control algorithms.
“AI-powered exoskeletons understand how a person moves and help how they move,” said Dante Archangeli, a graduate student and co-author.
“The motor can be switched between the right and left side of the main belt to move either leg.”
Unlike a powered suit that gives Iron Man the added strength or other exoskeleton suits that help heavy lifters, Professor Lindsey’s exoskeleton gives the user just enough extra power to walk.
The professor likens it to an electric bike with the motor helping its rider through the grueling process of riding the bike.
The team of researchers conducted a study in which six people with above-knee amputations tested their exoskeleton while their metabolic rate was recorded.
Patients walked on an electric carpet with and without the device while measuring levels of oxygen and carbon dioxide intake.
All of those who tested the exoskeleton improved their metabolic rate, in other words, reduced their energy expenditure, by an average of 15.6% while running it.
“It’s like taking off a 26-pound backpack. This is a really big improvement, he added, “We are very close to what the average person spends at the same speed.”
“Metabolic consumption is almost indistinguishable from that of a working person, depending on their level of fitness.”
Stan Sharr, who lost his left leg in an accident while helping a neighbour, said he never thought he would feel the sensation of walking effortlessly with two feet.
Shar, 74, said the experience of using the exoskeleton was as close to a human leg as possible.
He continued, “The first time I used it, I felt as if my muscles were completely fused with this exoskeleton, and it was helping them move faster.”
“It helped my legs relax and move forward and walk. I could probably walk miles with this thing because it was helping my muscles move.”
“I’m a person who doesn’t have a lot of muscle left in my remaining limb,” he says. ‘This device makes up for a lot that was taken from me.’
“There is nothing that will replace leg, flesh and bone, but this device is close to that. I hope to put this device on the market soon.”
That could happen quickly, Professor Lindsey said. And he believes that the exoskeleton could become available as early as a few years later.
The US Department of Defense has provided $985,000 (£724,000) in funding to develop this technology and new exoskeleton for veterans.
Earlier this year, Professor Lindsey and his team received a new grant of $584,000 (£429,000) from the National Science Foundation to further develop the device.
This could include further clinical studies to improve the device and improve its effectiveness for people with different types of amputations.