Tom Seibert was wakeboarding two years ago when the rope wrapped around his right hand and tightened, cutting into the bone. Doctors were later forced to amputate his hand because of a blood clot.
After the accident, Seibert, a sophomore in mechanical engineering, acquired a prosthetic hand for playing lacrosse and other activities, but the hand can only pick up objects by squeezing together and is cumbersome to use.
“It just opens and closes through a sensor,” Seibert said. “But my amputation is so high up that I’m limited to what I can wear. I usually just leave it at home.”
Thanks to the work of U researchers developing a signaling device for the brain, a prosthetic limb could respond to signals almost as fluidly as a normal body part.
“There are definitely some arms out there now, but they are terrible,” said Brad Greger, a bioengineering professor working on the project. “We’ve had soldiers from Iraq who have lost limbs, but they put the robotic arm on a shelf because they are too heavy and can’t do any coordinated movement.”
Researchers from multiple fields have been working on the project for about five years, using a signaling device developed by U researcher Richard Normann.
The device, patented as the Utah electrode array, takes nerve signals from the brain that direct limb movements and transfers them to a robotic limb.
“We’re serving as the middle people in someone’s nerve system,” said Greg Clark, another bioengineering researcher working on the project. “The whole scope is really extraordinary. We have to make these electrode arrays that have hundreds of electrodes attached to very thin wires.”
With the help of nanotechnology, the whole device is smaller than a pill.
Clark said the device reads signals from the brain by the number of pulses sent via nerves.
“When you think about moving your arm and sending a command down a nerve, it comes flying down the wire to the electrode array,” Clark said.
He said the device works like a computer reading pulses and interpreting whether the brain actually wants the limb to move.
“If there’s only a few pulses, the muscle isn’t in a moving state. But if you actually think of moving, the signal will be 30 pulses,” Clark said.
Greger said the U is only working on one part of the prosthetic arm research that is being funded by the U.S. Department of Defense. The project, which includes research from different universities around the country, costs an estimated $40 million.
John Hopkins University, a renowned research institution in Maryland, heads the project. Greger said the U receives about $5 million to $6 million to work on the signaling connection between the brain and robotic limb.
With about 10 different researchers running separate tests in labs across campus, the U started human trials over the summer to see if the signaling device would be able to trigger arm or leg movement.
Greger and other researchers received permission from patients with epilepsy at the U Hospital to implant the device and record brain signals.
“We’re actually putting devices in people, which is a big deal because the nervous system contains a lot of different cells,” Greger said.
The signals are recorded on a computer and tested on the array device. Greger said the next step is to see if the signals will make a virtual reality arm on the computer move as they want it to.
“We’re gearing up to use the real-time record where someone would lift their arm, and say push a computer mouse to different targets so we know where their arm is,” Greger said. “Then using the nerve data, decode it and see if it works in-line with the virtual reality arm.”
Besides testing it on a virtual arm, the U is looking into other technology that would be able to receive signals from parts of the brain the current device can’t access.
Greger said the same technology used to sense the location of epileptic seizures in a patient’s brain could also work in a prosthetic limb.
“The Utah array device is less invasive, but they are both basically a bunch of wires that rest on the brain,” Greger said. “The device was manufactured very safely in my lab. We’re the first people to do that.”
The device is still years from completion.
Seibert said he’s interested in the prosthetic limb U researchers are working on and whether it could work for him.
“It would be a lot nicer to have it respond like my hand used to,” Seibert said.
In the meantime, Seibert makes do without his right hand. He rides his skateboard to class every day and even goes wakeboarding occasionally.
“It’s the scariest thing I’ve ever done,” he said. “But you just get used to it.”
Lennie MahlerBradley Greger explains how a virtual reality program has the ability read brain signals and move prosthetic limbs. Greger?s goal is to have patients testing with the program by January 2009.
Lennie MahlerU researchers have been working with other top researchers for five years to develop the Utah electrode array chip. The U started to test the array chip in humans this summer.