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Written by AZoRobotiqueJuly 25, 2019
Keven Walgamott was convinced that he had to grab the egg without crushing it. What seems like a simple task for almost everyone can be a tougher challenge for Walgamott, who lost his left hand and part of his arm in an electrical accident 17 years ago.
But Walgamott was trying out the prototype of a high-tech prosthetic arm with fingers that can not only move but also move with his thoughts. Through a team of biomedical engineers from the University of Utah, he "felt" the egg so that his brain could tell the prosthetic hand not to grasp too tightly .
That's because the team, led by Gregory Clark, an badociate professor of American biomedical engineering, discovered a way for the "LUKE arm" (named after the robotic hand given to Luke Skywalker in "The Empire Strikes Back" To imitate the human hand feels the objects by transmitting the correct signals to the brain.
Their findings were reported in a new article co-authored by Jacob George, a doctoral student in biomedical engineering from Utah, and David Kluger, a former doctoral student, and by other colleagues in the recent issue of the journal . Robotic science.
We have changed the way we send this information to the brain so that it corresponds to the human body. And by matching the human body, we have seen better benefits. We make more biologically realistic signals.
Jacob George, Ph.D. student in Biomedical Engineering, University of Utah
This means that an amputee with the prosthetic arm would be able to feel the touch of something hard or soft, better understand how to grasp it and perform delicate tasks that would otherwise be unmanageable with a regular prosthesis with claws metal or hand hooks.
"It almost made me cry" Walgamott remembers the first use of the LUKE arm in clinical trials in 2017. "It was really amazing. I never thought that I would be able to feel that hand again. "
Walgamott, real estate agent of West Valley City, Utah, and one of seven trial participants at the university, was able to pick the grapes without crushing them, to seize an egg without damaging it and to hold the hand of his wife with sensation in the fingers. similar to that of a valid person.
"One of the first things that he wanted to do was to put his wedding ring. It's hard to do with one hand, " Clark said. "It was very moving."
These things are achieved through a complex series of mathematical calculations and modeling.
The LUKE arm
The LUKE arm has been under development for almost 15 years. The arm itself is composed mainly of metal motors and parts with a "skin" of transparent silicon on the hand. It is powered by an external battery and connected to a computer. It was built by DEKA Research & Development Corp., a company based in New Hampshire and created by the Segway's inventor Dean Kamen.
At the same time, the Utah team has developed a system that allows the prosthetic arm to tap into the wearer's nerves, which are like biological threads that transmit signals to the arm to move. It is thanks to an invention of the Utah biomedical engineer, Richard A. Normann, professor emeritus, called the Utah Electrode Slant Table.
The matrix is a roll of 100 microelectrodes and wires embedded in the amputee's nerves in the forearm and connected to a computer located outside the body. The matrix deduces the signals from the remaining arm nerves and the computer converts them into digital signals that instruct the arm to move.
But it also works in the other way. To perform tasks such as picking up objects, it takes more than the brain that asks the hand to move. The prosthetic hand must also know how to "feel" the object in order to know which pressure to apply, because we can not know it simply by looking at it.
First, the prosthetic arm contains sensors in its hand that transmit signals to the nerves via the matrix to mimic the feeling that the hand feels when it grabs an object. But the way these signals are transmitted is just as crucial. This involves understanding how the brain handles information transitions when it touches an object for the first time. At the first contact with an object, a push of impulses travels the nerves up to the brain, and then gradually decreases. Recreate it was a huge step.
Providing sensations is a big problem, but the way you pbad on this information is also important. If you make it more realistic biologically, the brain will understand it better and the performance of these sensations will also be better.
Gregory Clark, Associate Professor of Biomedical Engineering, University of Utah
To accomplish this, Clark's team used mathematical calculations as well as recorded impulses from a primate's arm to develop a rough model of how humans receive these various signals. This model was then added to the LUKE Arm system.
Future research
In addition to developing a prototype LUKE arm with a touch, the entire team is already creating a fully portable version that does not have to be connected to a computer outside the body. Instead, the whole would be wirelessly connected, offering the wearer complete freedom.
According to Clark, the inclined electrode network of Utah can also transmit signals to the brain that go beyond touch, such as temperature and pain, although the paper mainly deals with touch. While their work currently only concerns amputees who have lost their extremities below the elbow, where the muscles are to move the hand, Clark says their research could also be used even by those who lost their arms at above the elbow.
Clark thinks that by 2020 or 2021, three test participants will be able to use the arm, after approval by the federal authorities.
The project involves many institutions, including the Department of Neurosurgery of the U, the Department of Physical Medicine and Rehabilitation and the Department of Orthopedics, the Department of Biology and Anatomy of Organisms of the University of Chicago, the Biomedical Engineering Department of the Cleveland Clinic and the Utah Neurotechnology Societies, Ripple Neuro LLC and Blackrock Microsystems. The project is sponsored by the Defense Advanced Research Projects Agency and the National Science Foundation.
It's an incredible interdisciplinary effort. We could not have done so without the substantial efforts of all members of this team.
Gregory Clark, Associate Professor of Biomedical Engineering, University of Utah
(Video credit: University of Utah)
Source: https://www.utah.edu/
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