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NARR: In Daniel Ferris's laboratory at the University of Michigan, they develop robotic devices that help people walk. Ferris has designed a type of ankle brace that attaches the leg and uses the patient's own nerve signals to rehabilitate muscles that receive weakened signals from the spinal cord as a result of injury or neurologic disease. Ferris says the project owes its start to some tired physical therapists.
FERRIS: One of the therapies we were testing involved physical therapists assisting spinal cord injury patients to walking on a treadmill with the aid of a harness. It was having fairly good success but it was requiring an awful lot of physical effort by the physical therapist so my idea was to develop a robotic way of assisting the patient to practice walking that wouldn't require as much physical labor on the therapist's part.
NARR: So Ferris teamed up with a roboticist at the University of Washington to design the device he refers to as a "robotic exoskeleton". The idea itself is not new- several other research labs are working on similar devices that he readily admits are much more sophisticated than his. But the difference is those devices are all controlled by a computer, and Ferris' device is completely controlled by the patient.
FERRIS: Rather than having the computer decide based on some algorithm how to assist the person we are really putting the person totally in charge of how they get assistance.
NARR: The exoskeleton uses electrodes placed on the leg to detect the wearer's own weakened nerve signals, then translates those signals into motion via a set of pneumatic artificial muscles. The effect is to amplify the movement of the leg and put some spring back in patient's the step-
FERRIS: When you have a spinal cord injury you typically lose that ability to push off very strongly. And when we give the braces to the patients they get that extra burst back
SOT: pneumatic noise of device
NARR: That's one of the lab's healthy volunteers walking on a treadmill.
SOT: Subject stumbles.
Narr: She stumbles at first in response to the extra strength in her leg, but after about 30 minutes adapts to the device and walks normally.
SOT: pneumatic noise
NARR: and when the device is turned off, the effect is immediately felt
SOT: stopping pneumatic sounds, "wow my leg feels heavy"
NARR: As it turns out, giving the patient control over the therapy turned out to be good not just for the worn out physical therapists - it had a very specific benefit to the patients as well. Requiring the patient's own nervous system to do the work helped the muscles remember the movements even after the brace was removed. But Ferris says he wasn't always so certain that the results would be so positive.
FERRIS: We actually had fears that when you had patients walk with this type of system that they would become dependent on it, and that they would need the brace to do what they normally did. But it turns out that the results that we have so far are promising and that it does show that it has some therapeutic effects as a training tool.
NARR: Ferris explains how the device works:
FERRIS: The simplest way I can put it is when your nervous system wants to learn, it's hard to learn if the signal you send your muscles is very weak cause you don't get a good idea of how you're moving. But when we make the muscles stronger by using the exoskeleton, the nervous system has an easier time trying to control movement.
NARR: Ferris has only tested the device on a few patients with incomplete spinal cord injury and he says that while the results are promising its still to early to tell. However, if the exoskeleton lives up to its expectations, he envisions that other types of robotics could be adapted to use the same interface, ultimately providing assistance to many different types of patients. Gretchen Cuda, Columbia Radio News.