Starting materials with modern microprocessors and computer

Starting from the first peg legs and hand hooks, and ending with
the modern robotic and  myoelectric
prosthetics, the prosthetics were highly improved and developed. The ancient
Egyptians were the first culture who have used the prosthetic technology.1
They have made the prosthetic limbs of fiber.1

The Greville Chester Toe was made up of cartonnage and contact onto
the foot in fashion to Egypt sandals. 2 Cartonnage is a material
comparable to paper and is made of layers of linen or papyrus covered in plaster.
2 The purpose from this prosthetics was to maintain physical wholeness
in both their lives on Earth and in the afterlife.

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there is a wide believe that most of old prosthetics in
the past were not functional prosthetic and they were used for cosmetic
reasons, although some new discovery of an old prosthetic toe in an Egyptian
mummy Indicates that some of this old  prosthetic could have a real functional.1

In 1858, an old artificial leg was discovered at Capua,
Italy. This artificial leg was made of bronze and iron, with a wooden core. It is dating
to about 300 B.C.1

Ambroise Paré who was working in the French Army as a surgeon is
the father of modern prosthetic surgery.1 At 1529 he popularized new amputation procedures to the medical community.1
At 1536 he had created prostheses  for
upper and lower amputees.1 He had also created  an above-knee device which was adjustable and
had fixed position, actually this device had a lot of features that are used in
now in medical devices.1 This above-knee device is shown is figure
1.

 

Figure
1: The above-knee device that has been created by Ambroise Paré.1

 

After the World War II, The needing of
developing new Prosthetic has been increased.1
The government of United States of America has made a contract with companies
to develop prosthetic.1 Today’s modern devices have less weight,
and consists of different types of materials with modern microprocessors and
computer chips.1  Prostheses
become more realistic by covering it with silicone to be able to mimic the
appearance of real limbs to provide amputees with the most functional devices
and help them to return to the normal lifestyle.1

Prosthetic devices are common in both medical and engineering
fields. 2 These days many parts of a body can be replaced by a prosthetic. 2 Manufacturing process of prosthetic limbs becomes precise task to choose
a certain material that fit particular needs of a user’s and improving their
quality of life which they can’t achieve their tasks due to their disability.

 

3- The Materials

Materials, polymers, and ceramics and are
primary Materials that could be used in prosthetic fabrication. 4  Carbon fibers could be also
used. 4 There are different types of metals which could be  used in the prosthetic limbs such as: Aluminum, Titanium,
Magnesium, Copper, and Steel. 4 They are used for different
applications and in different amount. 4 In the past copper,
aluminum and iron were be used for the load bearing structure of the prosthetic,
but now it used for primarily as alloys or for plating to give more strength on
a prosthetic. 4  In general
, the most favorite metals to form the bulk prosthetic is
titanium due to its properties. It has good strength to weight and density
ratio, also it has light weight and low density and good to resist corrosion.
4  It has low modulus of
elasticity property which makes it similar to the bone. 4  This will allow the load to be distributed
between the bone and the implant which make the gait similar to the natural
gait. 4

Polymers are used in different application. It could be
used in coating the final product to give it the appearance of the skin. 4 When the prosthetic need to be waterproof, it could be coated using
special type of polymers. The common polymer which is used for this propose is Polyethylene
(PE). 4 It’s flexible more than plastic. 4

Carbon fibers have many properties that can
use in prosthetic limbs such as stiffness, high tensile strength, high chemical
resistance and low weight. 4 it susceptible to resist suddenly forces
acting on it. However carbon fibers are more costly in compared with other
material with the same properties. 4

4- Myoelectric Prosthetic:

Figure
2: Examples of different types of 
Myoelectric hands

a.Ottobock
DMC Plus. b.Touchbionics iLimb. .3

 

In 1940s and because of the highly development in computer devices and the algorithms science, Myoelectric upper limbs prosthesis has been developed.
3 A Myoelectric
prosthesis is a special type of prosthesis which uses the electrical tension
generated by a muscle contraction as order to move. 3

Using one muscle group, amputee’s
will be able to control and open a Myoelectric prosthesis  hand and close the Myoelectric prosthesis hand,
some new developed systems could provide wrist movement. 3 Some different
types of Myoelectric prosthesis are shown in figure 2.

In the mid-1970s a special pattern has been
developed to analyze the useful information that is presented in the
electromyographic (EMG). 3 This information could be used to make
more movements in different degrees. This technique is not widely used this
days because it needs high processing power. 3 Some disadvantages of this prosthesis is during daily living the arm
could be affected by several changes, like re-positioning of the electrode
which could affect the accuracy of pattern recognition. 3

Figure
3: A
simple illustration of the control strategies for Myoelectric prosthesis
.3

 

The advantages of changing intensity of
muscular contractions has been used to design a type of this prosthesis which
known as on/off control or crisp control prosthesis. 3 An Activation thresholds determine the
actions of the Myoelectric prosthesis. 3 For example if the muscle slightly contracted the hand Myoelectric
prosthesis will close. If the muscle strongly contracted the hand Myoelectric
prosthesis will open. If  no contraction
occurred in the muscle the prosthesis will be slightly contract. Figure
3 shows a better illustration for this example. More movements in different degrees could be evolved if different muscle group and more electrodes have been used. 3

Another different way to developing algorithms to analyze EMG signals is to record it from individual muscle groups. 3
This could occurred by implanting electrodes inside the
body, or by isolating the interest muscles nerves’ and amplify their signals.
3 This could gives better EMG signals since the subcutaneous fat could
affect the EMG signals quality. 3

5-Actions from thoughts:

Neuroscientists for a long time have interested in using brain
signals to control artificial devices. 5 One of the most important
technique which is used to do this call hybrid brain–machine interfaces (HBMIs).
5 “The word ‘hybrid’ reflects the fact that these
applications rely on continuous interactions between living brain tissue and
artificial electronic or mechanical devices”.5 The HBMIs combine
two types of application, the first type of HBMIs is a human-made
devices which generated electrical signals and transmit it to the brain tissue
in order to transmit some specific type of sensory information to mimic a
real  human nerve
and sensory function. 5 An important example for this type
is an auditory prosthesis. 5 The second type of HBMIs is a the
real-time and processing of the brain activities to control artificial devices.
An important example for this type would be the using of neural signals from
the motor cortex to control the movements of a prosthetic arm or leg in real
time. 5 A general description and organization of a type 2 HBMI is
shown in figure 4 .The applications that require alternate interaction between
the brain and artificial devices will have both type 1 and 2 HBMIs. 5

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure
4:
A general description and organization of
the type 2 HBMI .5

 

Unfortunately, the common non-
invasive electrophysiological methods to measure the electrical activity of the
neurons in cortex, such as scalp EEG recordings, lack the required resolution
which needed to control a robotic arm in real time. 5 For this
reason, multichannel intracranial recorders of brain activity are surgically
implanted to provide a raw brain signals to use it in the HBMIs. 5
It is important to design an appropriate instrumentation for recording and
processing the raw brain signals in real time. 5 This could be
done using VLSI chips, VLSI is defined as : “very large-scale integration,
the process of integrating hundreds of thousands of components on a single
silicon chip.”5 This neurochip must be small to
be implanted it in patients and it must work with replaceable batteries.5  It must be also wireless.
5  A prototype of this neurochip is shown in
figure 5.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure
5: A prototype of neurochip for processing brain signals. 5

 

After the processing and analyzing of signal was done using the
neurochip, the neurochip sends the data to robotic prosthetic processer, using
this data and by using some specific mathematical algorithm, the robotic
prosthetic processer compute the three-dimensional movement and start to move.
5   Figure 6
shows a brief explanation of neurorobotic prosthetic working method.

 

 

 

 

 

 

 

 

 

 

 

 

 

Figure
6:A brief explanation of neurorobotic prosthetic working method. 5

X-Flex-Foot:

 

 

 

 

 

 

 

 

 

 

 

Figure
7: Flex-foot is used in running competition. 6

In 1984 the first Flex-Foot was invented. 6
 The purpose of this developed prosthesis is to
make better rehabilitation for an amputee and make them able to run and to let them compete in running competition. 6  A running competition for amputees is
shown in figure 7. 6 This prosthesis is made from carbon fibre which is light-weight
and strong material. 7 6 The Flex-Foot was designed in a way that makes it gives more deflection, which improves the mechanism of running. 6   Like a spring, the Flex-Foot has the ability to store
kinetic energy using the amputee steps’ as potential energy, this will help the amputee to run and jump more easily. 6This type of prosthesis has obviously evolved in the last years. 6 A brief development history of the
Flex-foot is shown in figure 8. 6

Figure
8: The development history
of the Flex-foot. 6

 

The Flex-Foot is better than normal prosthetic, because it provides
higher walking and running speeds and consume less energy. 6 The producer
offers 18 different types of this prosthesis, every type is different from the
other in the stiffness. 6  The right type is chosen according to the
weight of the athlete. 6