Robot Prosthetics Technology
SMA Technology in Prostheses
Prosthesis is a growing technological advance in the field of Physical Therapy. As the capabilities
of technology increases, the capabilities of prosthetic limbs continue to increase as well.
Recent studies in the prosthetics field, prosthetic manufacturers have added a new type of
technology into robotic limbs. This type of technology is called Shape Memory Alloy (SMA).
Although an SMA required a lot of wires to be incorporated into prostheses, they are extremely
small and incredibly human like. These traits make them very desirable in the field of
prosthetics.
SMA’s allow for great range of motion and a significant amount of weight bearing for the
patient receiving the prosthetic limb. Also, SMA’s can be applicable to nearly every limb. For
example, one prototype of SMA is the ball and socket joints of the human shoulder. The
amount of motion is depended on the placement of the wires in the limb.
Prosthetics are becoming more and more common in today’s society as the number of
amputations in the United States is estimated to be about 1 in every 300 individuals each year.
As this increases, the need for advancement also increases.
SMA technology can also be applied to the replication of lost muscle. When this method is
used, there are normally several ways to approach it. Either there can be an extension to the
wires in the artificial limb or an extension in the rod of the limb. Also, it is important to consider
the angular motion of the limb. When determining this, the attachment of the SMA technology
is depended on the limb and length of the rod being used.
Mechanical Design of Prostheses
A mechanical approach can also be taken when manufacturing prostheses. Using the shoulder
example again, there are usually four main parts to the prostheses: the structure, cup, ball and
muscles. Some sort of aluminum rod poses as the bone of the limb while the other structures
are made of brackets. In this type of technology too, wires are used to replicate the muscles
and their functions.
The wires in the mechanically designed prostheses act differently than those of the SMA limbs.
The wires installed into this type of technology are designed to work against each other. For
example, if one wire is needed to lift the shoulder, then the other two wires will act by pulling
against the working wire, as leverage. This ensures that the joint is stable and acts as closely to
normal as it can.
Most Common Causes for Amputations in the United States
The most common causes for amputations, which usually lead to the use of prostheses, is modeled by
the pie chart below:
Causes for Amputations in the United
States
4% 4%
Disease
Trauma
22%
Congenital or Birth Defects
Tumors
70%
Chart Data From: http://www.surgeryencyclopedia.com/A -Ce/Amputation.html
SMA & Mechanical Date From:
http://74.125.155.132/scholar?q=cache:FDrYMcNcISIJ:scholar.google.com/+robo
tic+prosthetic+limbs&hl=en&as_sdt=8000&as_vis=1