prosthetic limbs by philip a. blair. overview prosthetics combines three main subjects: – biology...

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Prosthetic Limbs By Philip A. Blair

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Prosthetic Limbs

By Philip A. Blair

Overview

• Prosthetics combines three main subjects:– Biology• How the body connects to the synthetic limb.

– Technology• How the synthetic limb receives and sends information

from and to the body. Also, how the limb moves and it’s design.

– Psychology• How the user can use and sense the limb.

World War II

• Created a large amount of amputees.• In response the US National Academy of

Sciences created the Artificial Limb Program in 1945.– Military funding has since created vast

improvements in Prosthetic limbs.– Unlike the rest of history, we had technology.

Current Main Researchers

• Almost every major country.• In the United States:– A large amount of research is carried out through

the Defense Advance Research Projects Agency, aka DARPA.• Division of the military.• Investment is far above 100 million.

– NASA provides designs used on their missions that could be repurposed for prosthetics.

– Universities are often given grants.

Why does it matter?

• About 1.9 million people in the U.S. are amputees.– About 1 out of every 160– 54% - Vascular Disease (blood vessel issues).• Ex) Diabetes

– If one leg it lost to diabetes, there is a 55% chance to lose the other leg within 2 years.

• Over 90% lose their legs.

– 45% - Trauma• Ex) The armed forces.

Job Description From DARPA

• DARPA told the researchers two main things:– It must be less than 9 pounds.– They must be able to pick up a raisin or a grape

without squishing it and be able to tell the difference without seeing it.• At first, the researchers laughed and said it was

impossible, but they accepted the challenge (and money).

Modern Controllable Prosthetic

• Types:– Physical:

1. Using other body parts to act as signals.– Ex) Attaching straps to the other shoulder.

– Mental:1. Targeted Muscle Reinnervation (TMR)

– Using nerves to the missing limb and reconnecting it to muscles near the affected area.

2. Directly through the missing limb’s nerve.3. Directed by brain waves.

Control via other limbs

• A prosthetic can be controlled by other limbs or muscles that still work.– Controlled by the other shoulder, sensor on the feet, or

muscle for the limb that is still functional.– Can be mechanical or electrical.– The most common type has a “hook” attachment, but

others exist that are far more complex.– Can cost as low as $3,000.

• First use of this was in 1812.• http://www.youtube.com/watch?v=CaLVWlPshls

Phantom Limb

• A phantom limb is when a person still perceives a limb exist when it does not.– There have been reports of people stating that

their arm is cold or their finger hurts, when they no longer have that limb.

• The nerves that relate to that limb still exist.– The user can use their “Phantom Limb” to be able

to use the nerve controlled Prosthetics.

Targeted Muscle Reinnervation

• Nerve signals extremely complex to decode.– This is a brilliant work around.

• Researchers could not decode the brain’s nerve signals, so they rewired them to surrounding muscles.– They then could detect when a muscle was

being used and passed that information to the Prosthetic.

TMR Example

• It was the first time that a synthetic limb could be controlled by trying to move the missing limb.

• In other words, it was a thought to motion robot.

• http://www.youtube.com/watch?v=ddInW6sm7JE

Two way communication?

• An unexpected development is that the user developed the ability to feel temperature and pressure on their missing limb at the retargeted location.– How to relay that

information?– Current pressure

transmitters either too large or too heavy.

Direct Nerve Control

• Success made, but still under research.• User does not have to train or use other

muscles, only think to move their “phantom limb”.

• The Prosthetic can return information to the nerves and thus to the brain.– This could include pressure and temperature.

Materials to use

• They started with a Electronic Neural Interface.– Not completely biocompatible.

• Must be replace every 2 years.– Painful and expensive.

– Not MRI compatible.• Researching fiber optics.– Highly biocompatible.

• Last up to 70 years.

– Vastly faster• Enables two way communication on more areas.

Fiber Optics

Fiber Optics Implications

• Fiber optics can be used to patch spinal cord injuries.

• Advanced control and sense of artificial limbs.– Goal is to reach and exceed the “Luke” hand.– Addition of artificial skin that can sense pressure and

temperature.• “Never” have to replace.• http://

www.youtube.com/watch?v=ppILwXwsMng&feature=related 1:38-2:00

Downside

• It cost at least $90,000.• Still 3 years away from passing FDA

regulations.– Even though it is on the “fast-track”.

• Still under research.– But it has worked.

Brain Waves

• Toyota developed a wheelchair that can move forward, rotate, and stop by monitoring the brain waves of the user.– It has a reaction time of 125 milliseconds.

• Side note– Intel plans to have brain implants ready for customers by

2020.• Cause the iPhone will soon be boring.

• http://www.youtube.com/watch?v=yff20TlHv34&feature=related 4:19

Questions

• 1. What is a Phantom Limb?– When a person does not have

a limb, but can still sense it.

• 2. What is the first or second cause of amputation?– Trauma or blood vessel issues.

• 3. Do companies plan to someday plant chips in your head?– Yes.

Work Cited

• http://science.howstuffworks.com/prosthetic-limb1.htm• http://blog.smu.edu/research/2010/09/8/smu-leads-5-6m-res

earch-center-for-fiber-optic-interface-to-link-robotic-limbs-human-brain/

• http://www.popsci.com/scitech/article/2009-06/toyota-demonstrates-wheelchair-you-drive-your-brain

• http://www.amputee-coalition.org/healthcare-providers/limb-loss-statistics/index.html