Sunday, December 21, 2008

Luke...I am your father.

Think about how many times during the day you use your hands, whether it be to pick up something, to hold something, or to even feel something. Now imagine you no longer have your hands. You no longer have the ability to perform simple tasks like picking up an object. This is the case for millions of Americans who have lost their arm(s) and are unable to perform the same tasks that many of us take for granted every day.

Before the Luke arm, prosthetic arms only had three powered joints as well as three degrees of freedom. A
user could move their elbow, their wris t, and open and close some type of hook where the hand would normally be. The problem with this type of prosthetic is that it is frustrating to control and does not provide that much functionality (IEEE Spectrum). Often people who had lost their arms opted to not even wear this type of prosthetic because wearing the burdensome prosthetic was simply not justified by the small amount of assistance it provided. For as technologically advanced as this world had become, prosthetics was living in the age of the Flintstones. A new prosthetic had to be created that would give amputees’ more range of motion and fine motor control but it also had to be modular, usable by anyone with any level of amputation.

Technology has finally caught up and the Luke arm has been created. The Luke arm is a prosthesis named after the lifelike prosthetic worn by Luke Skywalker in Star Wars and was created by Dean Kamen. The Luke arm is a scientific breakthrough in the world of prosthetics due to its remarkable ability to act like a real human arm and hand. Microprocessors have been made small enough and power consumption has become efficient enough to place control electronics, lithium batteries, motors and wiring into a compartment the same size, shape and weight as the human arm. A human arm has a total of twenty two degrees of freedom, a lot more than the prosthetic arms most people are using now. What makes the Luke arm better than previous prosthetics is the fact that the Luke arm has eighteen degrees of freedom. The Luke arm has many degrees of freedom due to the enormous amount of circuitry inside the arm, which allows for its agility (technovelgy.com).

The Luke arm has tremendous motor control so that people who use the arm are able to pick up coffee beans one at a time, hold a power drill and even unlock a door.The reason the Luke arm has such fine motor control is the use of tactors. A tactor is a sma
ll vibrating motor-about the size of a bite size candy bar- that is placed against the user’s skin. A sensor on the Luke hand, which is connected to a microprocessor, sends a signal to a tactor, and that signal adjusts the grip strength of the hand. When a user grips something lightly, the tactor vibrates slightly. As the user’s grip tightens, the frequency of the vibrations increase (IEEE Spectrum). This is a non-operative way that allows users to pick up a paper cup without crushing it or firmly hold objects without dropping them.

Another way to control the Luke arm was discovered by neuroscientist Todd Kuiken of the Rehabilitation Institute of Chicago, who has successfully been able to surgically connect amputees’ residual nerves, which connect the upper spinal cord to the 70,000 nerve fibers in the arm, to the pectoral muscles. The patient thinks about moving the arm and signals travel down the nerves that were previously connected to the arm but are now connected to the chest. The chest muscles now contract in response to the nerve signals, instead of the arm muscles. The contractions are sensed by electrodes on the chest and those electrodes send signals to the Luke arm, allowing it to move (IEEE Spectrum). By using the Luke arm, amputees are still able to create signals from their brain to their arm; the only difference is that there is a robotic arm there instead.


Before the Luke arm is available to the public it must first be approved by the FDA, and it cannot be approved until several clinical trials have been performed.

Below is a video demonstrating how the Luke arm works and its capabilities.




References

Adee, Sarah. (February 2008). Dean Kamen’s “Luke Arm” Prosthesis Readies for Clinical Trial. Retrieved November 25, 2008, from
http://www.spectrum.ieee.org/feb08/5957

Chistensen, Bill. (2008, February 3). Luke Arm Robotic Prosthesis. Retrieved November 25, 2008, from http://www.technovelgy.com/ct/Science-Fiction-News.asp?NewsNum=1432

Pictures

http://www.spectrum.ieee.org/feb08/5957

http://robotslife.wordpress.com/2008/02/07/dean-kamens-luke-artificial-arm-gets-demoed-on-video/

Video

http://www.youtube.com/watch?v=R0_mLumx-6Y

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