T. Batler / UPMC / Pitt Health Sciences
A team from the University of Pittsburgh is trying to create an artificial limb that works like a limb. Star wars Movies.
“They’ve given him this new hand, and you can’t say it’s not his own,” said Lee Fisher, a biomedical engineer.
Luke even says “Ouch” when a medical droid pushes his artificial finger.
“This is our long-term goal,” Fisher said, “to recover the sensitive response from the missing organ.”
The human brain relies on a constant flow of sensitive information to perform basic tasks, such as holding a cup of coffee. Yet some sophisticated motorized organs – including those controlled only by a person’s thinking – do not respond in this way. As a result, even sophisticated prosthetics can often disappoint their users.
Fisher is one of more than 80 scientists, staff and trainees at the university’s Rehab Neural Engineering Lab working to add a touch of touch to synthetic materials. The goal is to equip artificial limbs with sensors that are connected to a person’s own nervous system.
Fisher’s lab, for example, is attaching artificial arms and legs to a device implanted in a person’s spine.
“It basically looks like a spaghetti noodle,” he says. “These can be inserted through a needle, so it’s a pretty minimally invasive process to hold them.”
The device was originally designed to reduce chronic pain by providing electrical impulses to the spine. But Fischer’s lab is using it to relay information from sensors to artificial hands or feet.
The technique is to stimulate the same nerve fibers that were once attached to a person’s own organ, Fisher said. That requires some trial and error.
“The first thing we do is just try and understand,‘ How did the stimulus feel? ’” He says. “Can we create a sensation that feels like it’s coming from their missing hand or their missing leg? Can we change the intense feeling of it?”
“There’s no hand, but I can feel it.”
A four-person survey suggests the answer is yes. Pat Bain, a participant whose right hand was amputated to stop the infection, described the stimulus in a video made by the university: “I know there are no hands, but I can feel it,” he says. “They may think the palm of my hand is the palm of my hand. It’s quite exciting.”
Participants also reported that stimulation reduces the perception of pain coming from a missing limb – a common problem after an amputation.
Fisher’s team is now working to use spinal implants to provide sensitive responses from prosthetic legs and feet.
“Additions can make these prostheses more useful, because we rely on the constant response of our feet to stay straight,” Fisher said. “We’re basically like an inverted pendulum that you have to turn around to keep the balance,” he says.
Preliminary results suggest that at least one person was helped by the reaction using an artificial leg.
“We’ve seen improvements in his balance control while standing, and some improvement in his durability and confidence as he walks,” Fisher said.
Reaching the mind alone
Jennifer Collinger, an associate professor in the university’s Department of Physical Medicine and Rehabilitation, said those who are paralyzed can also benefit from artificial limbs, including the feeling of touch.
For several years, the Pittsburgh Group has been working with paralyzed volunteers who have just learned to control a robotic arm using their thinking.
The goal is to develop technology that allows them to be more independent, Collinger said. “The way we’re going is to be able to feed ourselves, make food, be able to dress,” he says.
But things like this can be difficult if a person has to rely only on their eyes to know what the robotic arm is doing. So scientists in Pittsburgh are adding similar touch sensors that they use to enhance artificial weapons. But in this case, the sensitive information is being sent directly to the brain without going through the spine.
Robert Gant, a biomedical engineer, says a study of individuals found that the feeling of touch makes a big difference.
“Half the time it takes to pick up someone’s belongings and turn them around,” he said And in some cases, the person completes almost as fast as a person with a performance.
So far, scientists have only been able to give people who use prostheses a very primitive sense of touch.
Good enough to know the reaction when there is weight on one foot or an arm encounters an object, says Gant. But users often describe the sensation as vibration, humming, tingling or pressure.
“The information we have been able to provide is certainly not a perfect substitute for what they have lost,” Fisher said.
Information will improve as new sensors arrive, and scientists will find better ways to connect them to a person’s nervous system, Gaunt said. But it won’t soon match the sensitivity of Luke Skywalker’s artificial hand.
“Our ability to discriminate [among] Different types of objects, textures, surfaces, this is a difficult problem, “said Gaunt, although he hopes it is not unattainable.