MIT assistant professor Hugh Herr is an advanced prosthetics researcher and a bilateral leg amputee, two conditions that have allowed him the rare experience of testing his gadgets on himself.
"You know how it feels when you're at the airport and you hit the moving walkway? It's kind of like that," he said of a new foot-ankle system he's developing with colleagues at MIT, Brown University and the VA Medical Center in Providence, Rhode Island.
The so-called biohybrid system sports a power pack and computer all contained within the prosthesis and uses sensors to allow more realistic movements than static, strap-on devices. The first systems have noninvasive sensors attached to the prostheses. In about two years scientists will implant sensors into study volunteers' nervous systems, Herr said.
The prosthetics of the not-so-distant future are intertwined with muscles, nerves … even neurons. By Rachel Metz. [ You are here ]
Amputees who can't find the right prosthetics on the market build their own -- sometimes out of Legos. By Quinn Norton. [ Coming Sep 21 ]
Scientists are learning how amputees might eschew the prosthetic and grow back missing limbs. By Kristen Philipkoski. [ Coming Sep 22 ]
What if bionics get so good that we want them even if we don't need them? By Chris Oakes. [ Coming Sep 25 ]
"I've been an engineer-designer for a long time, but this is the first system (from which) I can benefit personally," he said. "It's kind of fun. I don't know why I waited this long."
Herr's enthusiasm is perhaps understandable, given his disability. But, in light of the immense strides scientists have achieved in prosthetics in the past decade, it is also well grounded. Improvements in materials for comfort and performance are part of the story. Of equal significance, scientists are probing the limits of mind-body interaction, developing tools that use artificial intelligence, muscle and neuron sensors -- and even plugging directly into the brain -- to achieve unprecedented results. Some patients need only to think to make a machine do their bidding.
The aggressiveness of the research has taken some people aback. "I would look under the hood and make sure the technology is as developed and is as good as they say it is," said Andrew Imparato, president and CEO of the American Association of People with Disabilities.
Even so, he added, further research could yield enormous benefits. "I think there's a lot about the human brain we don't fully comprehend. So if scientists are tapping into the brain to let people do things we haven't been able to do before, that's exciting," he said.
A breakthough could transform the lives of millions of people. The Amputee Coalition of America estimates between 1.8 and 1.9 million people in the United States live with some type of limb loss.
So just how close are we to a seamless blending of man and machine? In this four-part series, we take a look at some of the most promising -- and astonishing -- recent developments, from cutting-edge research labs to do-it-yourself garage mechanics that are changing our ideas of the body and its boundaries.
The Bionic ArmIn 2001, Jesse Sullivan, a high-power lineman, was nearly electrocuted and so badly injured that doctors had to amputate both of his arms. In 2002, he became the poster boy for the bionic arm when he appeared on national television wielding a computerized, biohybrid arm created by scientists at the Rehabilitation Institute of Chicago. On Thursday, Sullivan and the first woman to test the bionic arm, Claudia Mitchell, demonstrated their new abilities with the arm. Sullivan told reporters he can now trim hedges and mow the lawn. Mitchell, who lost her arm in a motorcycle accident, said the arm allows her to carry a laundry basket and fold clothes.
The researchers implant sensors within the pectoral muscles, attaching them to nerves that controlled elbows, wrists and hands before the amputations. The arm takes advantage of the fact that the brain can imagine moving an arm that isn't there -- a sometimes-unwelcome phenomenon for amputees known as "phantom arm" that can even involve pain in the missing limb.
Since the brain is still sending signals to the arm, the device can hijack messages telling muscles to move, or to feel touch or temperature. The researchers attach sensors from the device to the nerves, which attach and become intertwined with the nerves over time as the patient thinks about moving the arm.
When the prosthesis is strapped on, electrodes line up with the sensors to control the computer and motors in the bionic arm to operate the hand -- and all the user has to do is think.
The rewiring can causes minor side effects: "If you touch Jesse on his chest in certain places, he can feel it like it's his hand," said Todd Kuiken, director of the institute's Neural Engineering Center for Artificial Limbs, which developed the technology.
Five more amputees, including Mitchell, are now testing biohybrid arms. In the lab they use fancier arms with six motors, while the take-home version has three. Four of the volunteers are unilateral amputees, while one, like Jesse, has lost both limbs. All have received nerve implants, and the system is working for all but one patient, Kuiken said. The National Institutes of Health has provided $2 million of the $3 million Kuiken's lab has spent developing the arm.
A bionic leg is next on Kuiken's to-do list -- as prosthetic companies develop motorized legs, Kuiken hopes to adapt his technology to control them.
The Mind ReaderCyberkinetics' brain-computer interface, BrainGate, is a breakthrough device for people with spinal cord injuries. Plugged directly into the brain, the device allows paralyzed people to control a computer, flip switches and move a robotic hand -- by simply thinking.
Matthew Nagle, who was paralyzed from the neck down after being stabbed in 2002, was the first patient to try BrainGate. Sitting in a wheelchair with a plug protruding from his head he amazed everyone who saw him control a computer cursor or beat them at Pong.
Cyberkinetics scientists now say that BrainGate can even pick up brain signals from "locked-in" patients who are completely without movement or speech.
"They're desperate to communicate," said Cyberkinetics CEO Tim Surgenor.
The researchers recorded cortical activity from an ALS (Lou Gehrig's disease) patient. Another study volunteer who can't speak after a brainstem stroke used the BrainGate to type.
The brain implant sends signals to an external amplifier, which sends the messages through software that generates cursor movements or other electronic activity. The test system is wired, but the company's scientists say the final product will be wireless.
Surgenor hopes BrainGate will be FDA-approved in about four years.
The Second SightBlind patients were granted sight earlier this year in exchange for participating in a clinical trial testing a wireless retinal implant.
Researchers at Intelligent Medical Implants and IIP-Technologies in Europe created the Learning Retinal Implant System with hopes of returning sight to patients with damaged retinas. They successfully tested the device on four patients rendered blind by retinitis pigmentosa -- a disease that causes degeneration of the retina and leads to complete blindness in just a few years for one-third of those diagnosed. It affects 1 million people worldwide.
"If you talk to those people, even one single dot makes a difference," said Hans-Gurgen Tiedtke, CEO of IIP-Technologies.
The system includes glasses featuring a wireless transmitter and a mini-camera to pick up images. The glasses connect by cable to a processor pack worn at the waist that analyzes the information like a retina would, then send the image information to a chip implanted in the retina. The chip electrically stimulates the retina so ganglion cells can pick up the images. From there, the process continues like it would in a healthy eye: the information goes to the optic nerve, then to the brain and visual cortex where the information is reassembled as a picture.
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