Prosthetic Limb To Be Controlled By
Microchip
Source: Sandia National Laboratories
October 17, 2000
Albuquerque, N.M. -- "Smart" legs -- entire smart lower
limbs -- to replace those amputated from tens of thousands of
Americans yearly as a result of auto accidents, diabetes, or other
causes are expected to be on the market in two years. Sensors and
chips will be developed by the Department of Energy's
Sandia National Laboratories. Materials work and testing will be
performed by, strangely, the Russian nuclear weapons laboratory
Chelyabinsk 70. Technical requirements for the limb will be set by the
Seattle Orthopedic Group (SOGI).
"This is about making a leg that is more like a missing
limb than a collection of components ever can be," says Diane Hurtado
of the Smart Integrated Lower Limb (SILL) project team. "This limb
will have a digital control system to make it smart."
Says Ivan Sabel, president of Hangar, of which SOGI is a
division, "This is taking us -- an industry that has gone in 30 years
from plastic to carbon fibers -- to the next generation."
The advance should enable otherwise competent amputees
to maintain active lives rather than be confined to wheelchairs or
rest homes.
The leg is intended to simulate a human gait whether on
uphill, downhill, or even irregular terrain. To do so, a
microprocessor-controlled module implanted in the leg will respond to
sensor input from multiple sources. The microprocessor will control
hydraulic joints and piezoelectric motors that power the ankle, knee
and socket.
The leg socket will also adjust to the changing diameter
of an amputated stump over the course of a day, thus reducing sores,
improving comfort, and increasing time of use.
Clamoring to walk without falling down
"What amputees are clamoring for is a way to walk
without falling down, independent of terrain," says Sandia researcher
Dave Kozlowski, who has designed robotic architectures for surgical
operating rooms. "The majority of lower-limb prosthetic devices are
based upon passive technologies
that require far more energy for amputees to cover the same distance
as non-amputees."
In passive technologies, as the thigh moves forward,
inertia opens the knee joint, the artificial shin swings forward, and,
when the entire structure locks, the wearer can pass his or her weight
over it. The feet are usually not "smart" in adjusting to terrain.
"We intend to develop a much more efficient device, with
sensors placed at strategic points along foot and leg, that will
enable a more normal and efficient walking gait," says Kozlowski. A
proper limb motion will return energy to the wearer instead of
draining it, he says.
One challenge to be addressed is developing a power
source light enough for an amputee to feel comfortable carrying it, he
says.
Reducing pressure sores
Sandia researcher Mark Vaughn, who also will participate
in the project, says another goal is to make a self-adjusting
prosthetic socket that will prevent pressure sores caused by the
device rubbing against the residual limb. The device will change shape
to match the residual limb's swelling
over the course of a day.
"The funding gives us a couple of man-centuries of
Russian experimenters to throw at the problem, and it's right down
their alley," says Vaughn. "They're mechanical guys. We should get
quite a bit of accommodation."
Approximately 120 Russian scientists formerly employed
designing nuclear weapons are expected to participate in the project,
funded by DOE's Initiatives for Proliferation Prevention.
Says Sandia manager for international initiatives Bob
Huelskamp, "Sandia generally thinks it's impressive if, say, five of
its scientists leave to start an entrepreneurial enterprise. This
prosthetics project means that, at a minimum, dozens, and if the
project takes off, triple figures of Russians
formerly in the weapons-of-mass-destruction business are moving out of
that into a humanitarianly useful, and hopefully commercially
successful, business venture."
The Russians bring impressive skills and equipment to
the research effort, he says.
Says Olen Thompson, "SILL got its start through the
integrated efforts of the principal investigators, CRADA specialists,
licensing specialists, patent attorneys and the DOE's Technology
Partnership Office in Albuquerque. They had many barriers to overcome
but they stayed with it because they
believed in the project's importance."
DOE is funding the current effort with $1.5 million over
two years. SOGI is expected to put up a matching amount in money,
goods, and services.
Changing the world
Hurtado takes over project management of Sandia's
prosthetics program from recently retired Sandian Mort Lieberman, who
originated it. Two years ago, an agreement he helped create between
Sandia, Chelyabinsk 70, a Boston University professor and an Ohio
prosthetics company produced an
artificial foot that has received impressive reviews. Last year, work
was started on an artificial knee.
Lieberman, who spoke at the Sept. 26, 2000, cooperative
research and development (CRADA) signing, discussed the change in
direction at the Russian nuclear lab and, to some extent, at Sandia (a
national security laboratory) initiated by his work. Quoting
anthropologist Margaret Mead, he said, "Never doubt that a small group
of concerned citizens can change the
world."
Sandia is a multiprogram DOE laboratory, operated by a
subsidiary of Lockheed Martin Corp. With main facilities in
Albuquerque, N.M., and Livermore, Calif., Sandia has major research
and development responsibilities in national security, energy, and
environmental technologies.
http://www.sandia.gov/media/NewsRel/NR2000/smartleg.htm