Bionics 4

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Bionics 4

• Kevin Warwick

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Artificial Limbs

• An artificial limb usually replaces a missing
  limb, such as an arm or leg.
• The type of artificial limb used is determined
  largely by the extent of amputation of the
  missing extremity each one is a little
  different.
• Reasons include disease, accidents, and
  congenital (birth) defects.

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Geography

• Likely reasons for an amputation depend on
  location.
• In USA Europe circulatory disease, cancer and
  infection are the leading causes.
• In Africa the most likely causes are industrial,
  vehicular, or a war related accidents again
  infection is a problem.

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This Presentation

• More interested in the legs and arms themselves
• Neuroprosthetics Enhancements etc are mostly a
  separate lecture

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History

• Two artificial toes have been found on Egyptian
  mummies these date back to 1,000BC. However it
  is not known if they were actually used in life.
• The first artificial leg, from archaeology, is
  the Roman Capua Leg. This was found in a tomb in
  Capua, Italy, and dates back to 300BC. It was
  made of wood and copper.
• In the 15th century artificial limbs were often
  made out of iron for soldiers and sailors.
  However wood came to be used much more, simply
  because of its weight.

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Wooden Legs

• Such a wooden leg could be simply fixed.
• Or it could be hinged at the knee to assist
  walking
• No hinge possible strange gait

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Developments

• In the 19th century, artificial limbs became more
  widespread due to the large number of amputees
  from wars.
• Helped by the discovery of anesthetics.
• In the 20th century scientific research and
  commercial possibilities opened the field
  further.
• In recent years, a great deal of emphasis has
  been placed on developing artificial limbs that
  look and move more like actual human limbs.
• General new technology (plastics, CAD,
  manufacturing, medicine) have all improved the
  end results.

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Types of Prosthetic

• Transtibial Prosthesis replaces a leg missing
  below the knee. Such amputees can regain normal
  movement more readily than those with a
  transfemoral amputation - retaining the knee
  allows for easier movement.
• Transfemoral Prostheses replaces a leg missing
  above the knee. Such amputees can have a very
  difficult time regaining normal movement. A
  transfemoral amputee must use approximately 80
  more energy to walk than a person with two whole
  legs.
• Transradial Prostheses replaces an arm missing
  below the elbow. Two main types of prosthetics
  are available. Cable operated limbs work by
  attaching a harness and cable around the opposite
  shoulder of the damaged arm. Alternative is
  myoelectric arms muscle sensing.
• Transhumeral Prosthesis replaces an arm missing
  above the elbow. Such amputees experience some of
  the same problems as transfemoral amputees, due
  to the similar complexities associated with the
  movement of the elbow. Mimicking the correct
  motion with an artificial limb is very difficult.

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Recent Developments

• New plastics and other materials, such as carbon
  fibre, have allowed artificial limbs to be
  stronger and lighter, limiting the amount of
  extra energy necessary to operate the limb. This
  is especially important for transfemoral
  amputees.
• Other synthetic materials have allowed artificial
  limbs to look much more realistic, which is
  important to transradial and transhumeral
  amputees because they are more likely to have the
  artificial limb exposed.

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Artificial Legs

• Is only one leg missing?
• How much of the leg is missing?
• Clearly these issues are vital to the type of
  artificial leg needed
• The more to be replaced, so the more difficult
  the problem is.

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C-Leg

• The best known present day artificial leg is the
  C-Leg produced by Otto Block.
• The user can choose between two modes one for
  walking and one for bicycling (or any other
  preprogrammed activity). The "problem" is
  switching between modes, as the wearer has to
  swing the leg forward in a jerky fashion.
• The C-LEG supports up to 10 programmable modes,
  switchable through a small remote control device
  about the size of a car alarm remote.
  Reprogramming a mode with another special
  activity requires a technician.

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C-Leg

• An inbuilt microprocessor interprets the users
  movements and anticipates their actions, allowing
  motion changes in real time.
• The system is actuated through the legs
  hydraulic movement.
• It gives users greater flexibility to change
  speed or direction without sacrificing stability.

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C-Leg

• The 10 switchable modes enable various sports
  activities, including cycling, running, natural
  driving and other programmable activities that
  require different leg actions to normal walking
  and stair climbing.
• Current challenges are to stretch the units
  battery life to 50 hours on one charge and to
  make the leg salt-water resistant. These are both
  requirements to support military use.

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Heather Mills

• In August 1993 Heather was hit by a police
  motorcycle by Kensington Palace, London.
• Her injuries included crushed ribs and a
  punctured lung. She needed a metal plate put into
  her pelvis and also the amputation of her left
  leg below the knee.
• Mills has a prosthetic leg, taking it off and
  showing it to USA talk show host Larry King
  during his interview with her in October 2002.

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Feet

• With artificial legs usually the knee joint is
  critical
• Feet tend to be either non-existent, e.g. Aimee
  Mullins, or are more for cosmetic purposes they
  are not functional
• Stability is important but not dexterity
• Tend to be purpose directed what is the leg
  for?

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Artificial arms and hands

• Stability and power carrying are not big issues
  here
• Elbow joints clearly are important
• But most critical are hand movements what will
  the hand have to do? how is it to be
  controlled? what will it look like?
• Functionality is important but cosmetics are
  also very important

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Artificial Arms and Hands

• Important if one or both have been lost
• It is possible to do many activities with one
  hand or using a residual limb(s).
• Many arm amputees do not use any prostheses or
  special tools. It is easy and possible to get
  dressed/write/type with one hand.
• Some continue their work with a special
  attachment only e.g. carpentry, car driving.
• Nevertheless, having a prosthesis can be a big
  help, especially for manual labour.

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Prosthesis

• Learning to use a prosthesis takes hard work and
  practice. It is only worth the effort if it
  improves a persons ability to hold and use
  things.
• An arm-hand prosthesis has three basic parts the
  socket, which fits over the residual limb the
  arm section, which may or may not include an
  elbow joint and the hand/tool, which can be like
  a hand, a hook, or some other shape to allow the
  person to hold and use things.
• Often a hook is preferred as it is extremely
  functional

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Body-powered prostheses

• Some prosthetics clinics make available
  body-powered arm prostheses.
• These have straps or cables that attach to other
  parts of the body, so that by moving a shoulder,
  the person can make the hand close or bend the
  elbow of the prosthesis.
• Body-powered prostheses often have metal hooks
  instead of fingers. The hooks are better than
  artificial fingers for hard work and can pick up
  smaller things.

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Electric-powered prostheses

• Electrical prostheses are available in some
  countries, but they are relatively expensive.
• Perhaps not available where they are needed -
  most (countries at war/strife).
• Muscles in the arm operate electric motors, which
  close and open the hand.
• Electrical prostheses look more like real arms,
  but they are not as strong and they break more
  easily.

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Cosmetic prostheses

• Cosmetic arms look like real arms but the hands
  either do not move at all or can be pulled (by
  another hand) into a fixed position.
• They can help a little (for example, the cosmetic
  arm can hold down a paper while the other hand
  writes on it), but the real purpose of a cosmetic
  arm is to look natural.
• Very useful for someone in the public eye.
• Useful if only one hand has been lost.

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Krukenberg surgery

• Some people missing both hands choose to have
  surgery, called the Krukenberg surgery.
• This separates the two bones of the forearm to
  make a new kind of hand.
• The bones can be used like two fingers, and
  because the skin and bones are real, the person
  can feel what they are doing.
• This greatly benefits amputees who are blind.
• It is still possible to wear a prosthesis over
  the residual limb even after the surgery.

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The i-LIMB Hand

• From Touch Bionics
• http//www.touchbionics.com/

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The i-LIMB Hand

• The i-LIMB Hand is controlled by a system that
  uses a two-input myoelectric (muscle signal) to
  open and close the hands fingers.. This signal
  is picked up by electrodes that sit on the
  surface of the skin. Existing users of basic
  myoelectric prosthetic hands are able to adapt to
  the system and can master the devices
  functionality within minutes.

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Bionic Arm

• In 2001 Jesse Sullivan lost both his arms when he
  was electrocuted.
• He has received an artificial arm/hand controlled
  from his nervous system.
• The nerves that used to go to the arm were moved
  onto chest muscles. The nerves grew into the
  chest muscles, so when Jesse thinks "close hand,"
  a portion of his chest muscle contracts and
  electrodes that detect this muscle activity tell
  the computerized arm to close the hand. Thus,
  Jesse thinks "close hand" and his artificial hand
  closes.
• Work of Todd Kuiken.

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Claudia Mitchell

• Lost her left arm in a motorcycle accident.
• In 2007 became the 4th person to have this type
  of procedure Rehab Institute of Chicago

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Next Lecture

• Deep Brain Stimulation