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Unit-B: Human Organ Systems and

Biodesigns
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Module 2

HUMAN ORGAN SYSTEMS AND BIO DESIGNS – 1

2.1 Brain as a CPU System:

The human brain can be thought of as a highly sophisticated and complex information
processing system, similar to a computer's Central Processing Unit (CPU). Both the brain and
CPU receive and process inputs, store information, and perform calculations to produce
outputs. However, there are significant differences between the two, such as the way they store
and process information and the fact that the human brain has the ability to learn and adapt,
while a computer's CPU does not. Additionally, the human brain is capable of performing tasks
such as perception, thought, and emotion, which are beyond the scope of a computer's CPU.
Table: Comparison Chart

Basis for Brain Computer

Comparison
Computer Neurons and synapses ICs, transistors, diodes,
capacitors, transistors, etc
Memory growth Increases each time by Increases by adding more
connecting synaptic links memory chips
Backup systems Built-in backup system Backup system is constructed
manually
Memory power 100 teraflops (100 trillion 100 million megabytes
calculations/seconds)
Memory density 107 circuits/cm3 1014 bits/cm3
Energy consumption 12 watts of power Gigawatts of power
Information storage Stored in electrochemical and Stored in numeric and symbolic
electric impulses. form (i.e. in binary bits).
Size and weight The brain's volume is 1500 Variable weight and size form
cm3 and weight is around 3.3 few grams to tons.
pounds.
Transmission of Uses chemicals to fire the Communication is achieved
information action potential in the neurons. through electrical coded signals.
Information Low High
processing
power
Input/output Sensory organs Keyboards, mouse, web
equipment cameras, etc.
Structural Self-organized Pre-programmed structure
organization
Parallelism Massive Limited
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Reliability and Brain is self-organizing, self- Computers perform a

damageability maintaining and reliable. monotonous job and can't
properties correct itself.

2.1.1 Architecture
The architecture of the human brain as a CPU system can be compared to that of a parallel
distributed processing system, as opposed to the Von Neumann architecture of traditional
computers.

Figure: Comparison between Brains Computing System with Conventional Von Neumann
Computing System
In the human brain, information is processed in a distributed manner across multiple regions,
each with specialized functions, rather than being processed sequentially in a single centralized
location. Just like how a computer's CPU has an arithmetic logic unit (ALU) to perform
mathematical calculations, the human brain has specialized regions for processing
mathematical and logical operations. The prefrontal cortex, for example, is responsible for
higher-level cognitive functions such as decision making and problem solving.
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Figure: Schematic representation of the frontal lobes of brain

Similarly, a computer's CPU also has memory units for storing information, and the human
brain has several regions dedicated to memory storage, including the hippocampus and
amygdala.

Figure: Limbic system. Cross section of the human brain. Mammillary body, basal ganglia,
pituitary gland, amygdala, hippocampus, thalamus - Illustration Credit: Designua /
Shutterstock
While the comparison between the human brain and a computer's CPU can provide useful
insights, it is important to note that the human brain is a vastly more complex and capable
system, with many functions that are still not fully understood.
2.1.2 Human Nervous System
In the human body, the neural system integrates the activities of organs based on the stimuli,
which the neurons detect and transmit. They transmit messages in the form of electrical
impulses and convey messages to and from the sense organs. Thus, the nervous coordination
involves the participation of the sense organs, nerves, spinal cord, and brain.

2.1.2 CNS and PNS

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Figure: Representation of CNS and PNS

One of the most complex organ system to ever evolve, the human nervous system consists of
two parts, namely:
1. Central Nervous System (consists of the brain and spinal cord)
2. Peripheral Nervous System (includes all the nerves of the body)
Central Nervous System
Central Nervous System (CNS) is often called the central processing unit of the body. It consists
of the brain and the spinal cord.
Brain
The brain is one of the important, largest and central organ of the human nervous system. It is
the control unit of the nervous system, which helps us in discovering new things, remembering
and understanding, making decisions, and a lot more. It is enclosed within the skull, which
provides frontal, lateral and dorsal protection. The human brain is composed of three major
parts:

• Forebrain: The anterior part of the brain, consists of Cerebrum, Hypothalamus and
Thalamus.
• Midbrain: The smaller and central part of the brainstem, consists of Tectum and
Tegmentum.
• Hindbrain: The central region of the brain, composed of Cerebellum, Medulla and Pons.
Spinal Cord
The spinal cord is a cylindrical bundle of nerve fibers and associated tissues enclosed within
the spine and connect all parts of the body to the brain. It begins in continuation with the
medulla and extends downwards. It is enclosed in a bony cage called vertebral column and
surrounded by membranes called meninges. The spinal cord is concerned with spinal reflex
actions and the conduction of nerve impulses to and from the brain.
Peripheral Nervous System
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Peripheral Nervous System (PNS) is the lateral part of the nervous system that develops from
the central nervous system which connects different parts of the body with the CNS. We carry
out both voluntary and involuntary actions with the help of peripheral nerves.
Classification of the peripheral nervous system:
1. Somatic neural system (SNS): It is the neural system that controls the voluntary actions
in the body by transmitting impulses from CNS to skeletal muscle cells. It consists of
the somatic nerves.
2. Autonomic neural system (ANS): The autonomic neural system is involved in
involuntary actions like regulation of physiological functions (digestion, respiration,
salivation, etc.). It is a self-regulating system which conveys the impulses from the CNS
to the smooth muscles and involuntary organs (heart, bladder and pupil). The autonomic
neural system can be further divided into:
• Sympathetic nervous system
• Parasympathetic nervous system
The sympathetic system controls “fight-or-flight” responses. In other words, this system
prepares the body for strenuous physical activity. The events that we would expect to occur
within the body to allow this to happen do, in fact, occur. The parasympathetic system regulates
“rest and digest” functions. In other words, this system controls basic bodily functions while
one is sitting quietly reading a book.

2.1.3 Signal Transmission

Signal transmission in the brain occurs through the firing of nerve cells, or neurons. A
neuron receives inputs from other neurons at its dendrites, integrates the information, and then
generates an electrical impulse, or action potential, that travels down its axon to the synaptic
terminals. At the synaptic terminals, the neuron releases chemical neurotransmitters, which
cross the synaptic gap and bind to receptors on the postsynaptic neuron, leading to the initiation
of another action potential in the postsynaptic neuron.

This process of transmitting information from one neuron to another is known as

synaptic transmission and forms the basis of communication within the brain. Different types
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of neurotransmitters have different effects on postsynaptic neurons, and the balance of

neurotransmitter levels can influence brain function, including mood, learning, and memory.
Signal transmission in the brain is also influenced by various forms of synaptic plasticity,
including long-term potentiation (LTP) and long-term depression (LTD), which can modify
the strength of synaptic connections and contribute to learning and memory processes.
2.1.4 EEG
EEG stands for electroencephalography, which is a non-invasive method for measuring
the electrical activity of the brain. An EEG records the electrical signals generated by the brain's
neurons as they communicate with each other. The signals are recorded through electrodes
placed on the scalp and the resulting EEG pattern provides information about the synchronized
electrical activity of large populations of neurons.

Figure: Representing EEG

Applications of EEG
Some of the most common applications of EEG are:
• Diagnosis of Epilepsy: EEG is a widely used tool to diagnose epilepsy and other
seizure disorders. It can detect abnormal electrical activity in the brain, which
can help to confirm the diagnosis and determine the location of the seizure
focus.
• Sleep Studies: EEG is often used in sleep studies to evaluate sleep patterns an
diagnose sleep disorders.
• Brain-Computer Interfaces (BCI): EEG can be used to control external devices
such as prosthetic limbs or computer software. This is done by detecting specific
brain waves associated with a particular mental state, such as concentration or
relaxation.
• Research on Brain Function: EEG is used in research to study brain function
during various activities such as reading, problem-solving, and decision-
making. EEG can also be used to investigate how the brain responds to stimuli
such as light, sound, and touch.
• Diagnosis of Brain Disorders: EEG can be used to diagnose a wide range of
brain disorders including dementia, Parkinson's disease, and traumatic brain
injury.
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• Anesthesia Monitoring: EEG can be used to monitor the depth of anesthesia

during surgery to ensure that the patient remains in a safe and comfortable state.
• Monitoring Brain Activity during Coma: EEG is also used to monitor brain
activity in patients who are in a coma to determine the level of brain function
and assess the likelihood of recovery.

EEG Signals and Types of Brain Activity

EEG signals have unique features that correspond to different types of brain activity.
Here are some of the main types of brain activity that can be detected with EEG:
• Delta waves (0.5-4 Hz): Delta waves are low-frequency waves associated with dee
sleep,
infancy, and brain disorders such as brain damage or dementia.
• Theta waves (4-8 Hz): Theta waves are also associated with sleep and relaxation, as
well as meditation and hypnosis. They are also present during memory encoding and
retrieval processes.
• Alpha waves (8-12 Hz): Alpha waves are present when the brain is relaxed and not
focused on any particular task. They are also associated with meditation and creativity.
• Beta waves (12-30 Hz): Beta waves are present when the brain is focused on a task,
such as problem-solving or decision-making. They are also associated with anxiety and
stress.
• Gamma waves (30-100 Hz): Gamma waves are associated with high-level cognitive
processing, such as attention, perception, and memory. They are also involved in
sensory processing and motor control.

The analysis of EEG signals can provide valuable information about brain function and
activity, as well as offer insights into the workings of the human mind.

Figure: Representing EEG signal and the mental state of brain

2.1.5 Robotic Arms for Prosthetics
Robotic arms for prosthetics are advanced prosthetic devices that use robotics
technology to restore functionality to individuals with upper limb amputations. These devices
typically use motors, actuators, and sensors to mimic the movements of a human arm and hand,
allowing the wearer to perform tasks such as reaching, grasping, and manipulating objects.
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Robotic arms for prosthetics can be controlled in a variety of ways, including direct control
through muscle signals (myoelectric control) or brain-machine interfaces, which use electrodes
implanted in the brain or placed on the scalp to detect and interpret brain activity.
Some prosthetic arms also incorporate machine learning algorithms to improve their
performance and adapt to the user's needs over time.

Robotic Arm Prosthetic Direct Control through Muscle Signals (myoelectric control)
Myoelectric control of a robotic arm prosthetic involves using the electrical signals
generated by the wearer's remaining muscles to control the movement of the prosthetic. The
system typically involves electrodes placed on the skin over the remaining muscle that are used
to detect and interpret the electrical signals generated by the muscle contractions.

Figure: Representation of myoelectric control of an ankle exoskeleton

When the wearer contracts their muscles, the electrodes detect the electrical signals and
send them to a control unit, which interprets the signals and uses them to control the movement
of the robotic arm. Depending on the specific design, the control unit may use pattern
recognition algorithms to determine which movement the wearer is intending to perform, or
the wearer may use a combination of muscle signals to control specific degrees of freedom in
the prosthetic arm.
Myoelectric control has the advantage of being directly controlled by the user, allowing
for a more intuitive and natural interaction with the prosthetic. It can also provide a high level
of control and precision, as the electrical signals generated by the muscles are unique to each
individual and can be used to perform a wide range of movements.
However, myoelectric control systems can be complex and may require extensive
rehabilitation and training to use effectively, as well as ongoing maintenance to ensure proper
function. Additionally, the system may not be suitable for individuals with muscle weakness
or other conditions that affect the ability to generate strong electrical signals.

Robotic Arm Prosthetic by Brain-Machine Interfaces

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Brain-machine interfaces (BMIs) are a type of technology that allows a user to control a robotic
arm prosthetic directly with their brain activity. The system typically involves electrodes placed
on the scalp or implanted directly into the brain to detect and interpret the user's brain signals.

Figure: Representing brain-machine interfaces

When the user thinks about moving the prosthetic arm, the electrodes detect the
corresponding brain activity and send the signals to a control unit, which uses algorithms to
interpret the signals and control the movement of the prosthetic. The user can then control the
movement of the prosthetic in real-time by thinking about the desired movement.
BMIs have the advantage of providing a direct and intuitive connection between the
user's brain and the prosthetic, allowing for a high level of control and precision. Additionally,
BMIs can be used to provide sensory feedback to the user, allowing them to experience the
sensation of touch through the prosthetic.
However, BMIs can be complex and invasive systems, requiring surgical implantation
and ongoing maintenance to ensure proper function. Additionally, they may not be suitable for
individuals with conditions that affect brain activity or who are unable to generate strong
enough brain signals to control the prosthetic effectively. Ongoing research and development
is aimed at improving the performance and accessibility of BMIs, as well as increasing their
ease of use and reliability.

Parkinson’s Disease
It is a progressive disorder that affects the nervous system and the parts of the body
controlled by the nerves. Symptoms start slowly. The first symptom may be a barely noticeable
tremor in just one hand. Tremors are common, but the disorder may also cause stiffness or
slowing of movement.
In Parkinson's disease, certain nerve cells (neurons) in the brain gradually break down
or die. Many of the symptoms are due to a loss of neurons that produce a chemical messenger
in your brain called dopamine. When dopamine levels decrease, it causes atypical brain activity,
leading to impaired movement and other symptoms of Parkinson's disease.
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Parkinson's disease can't be cured, but medications can help control the symptoms,
often dramatically. In some more advanced cases, surgery may be advised. Your health care
provider may also recommend lifestyle changes, especially ongoing aerobic exercise.

2.1.6 Engineering Solutions for Parkinson’s Disease

Parkinson's disease is a neurodegenerative disorder that affects movement and motor function.
There are several engineering solutions aimed at improving the quality of life for individuals
with Parkinson's disease, including:
Deep Brain Stimulation (DBS): DBS involves the implantation of electrodes into specific
regions of the brain to deliver electrical stimulation, which can help to relieve symptoms such
as tremors, stiffness, and difficulty with movement.
Exoskeletons: Exoskeletons are wearable devices that provide support and assistance for
individuals with mobility issues. Some exoskeletons have been developed specifically for
people with Parkinson's disease, and can help to improve balance, reduce tremors, and increase
overall mobility.
Telerehabilitation: Telerehabilitation involves the use of telecommunication technology to
provide physical therapy and rehabilitation services to individuals with Parkinson's disease,
without the need for in-person visits to a therapist.
Smartwatch Applications: Smartwatch applications can be used to monitor symptoms of
Parkinson's disease, such as tremors, and provide reminders and prompts for medication and
exercise.
Virtual Reality: Virtual reality systems can be used for rehabilitation and therapy for
individuals with Parkinson's disease, providing interactive and engaging environments for
patients to practice movements and improve coordination and balance.
These engineering solutions have the potential to significantly improve the quality of
life for individuals with Parkinson's disease, and ongoing research and development is aimed
at improving their effectiveness and accessibility. However, it is important to note that these
technologies are not a cure for Parkinson's disease and should be used in conjunction with other
forms of treatment and care.

Figure: Representing typical appearance of Parkinson’s disease

2.2 Eye as a Camera System:

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The human eye can be analogized to a camera system, as both the eye and a camera capture light
and convert it into an image. The main components of the eye that correspond to a camera system
include:
• The Cornea: This transparent outer layer of the eye functions like a camera lens, bending
light to focus it onto the retina.
• The Iris: The iris functions like the diaphragm in a camera, controlling the amount of light
that enters the eye.
• The Pupil: The pupil functions like the aperture in a camera, adjusting the size to control
the amount of light entering the eye.
• The Retina: The retina functions like the camera film or sensor, capturing the light and
converting it into electrical signals that are sent to the brain.
• The Optic Nerve: The optic nerve functions like the cable connecting the camera to a
computer, transmitting the electrical signals from the retina to the brain.

Figure: Comparing camera and anatomy of eye

In both the eye and a camera, the captured light is transformed into an image by the lens and
the light-sensitive component. The eye processes the image further, allowing for visual
perception, while a camera stores the image for later use.
It's important to note that the eye is much more complex than a camera and has several
additional functions, such as adjusting for different levels of light and adjusting focus, that are
not found in a camera. The eye also has the ability to perceive depth and colour, as well as
adjust to movements and provide a continuous, real-time image to the brain.

Figure: Representing anatomy of eye

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Parts of the Human Eye

• Sclera: The outer covering of the eye is called the sclera. It is a protective tough white
layer (white part of the eye).
• Cornea: The transparent part in front of the sclera is called the cornea. Light enters the
eye through the cornea, it bends(refracts) the light passes through it. It also protects the
eye and also doesn't allow foreign particles to enter the eye.
• Iris: It is a dark, muscular tissue and ring-like structure present behind the cornea. The
colour of the eye is due to the colour of the iris. The iris regulates the amount and
intensity of light entering the eyes by adjusting the size of the iris.
• Pupil: The pupil is a small opening in the iris. The iris controls the size of the pupil.
The pupil’s function is to adjust the amount of light entering the eye.
• Lens: The transparent portion situated behind the pupil is called the lens (convex lens
which thicker at the center than the edges). It focusses all the light at one point. The
lens alters the shape to focus light on the retina, with the help of ciliary muscles. It
becomes small to focus on objects at a distance and becomes big to focus on nearby
objects.
• Retina: It’s the inner boundary of the eye. It is the light-sensitive layer that consists of
nerve cells. Its function is to convert the images formed by the lens into electrical
impulses. These electrical impulses are then transmitted through optic nerves to the
brain.
• Optic Nerves: Light coming from retina is sensed by the nerve cells. You can find two
types of optic nerves, which are cones and rods.
1. Cones: Cones are the nerve cells that are more sensitive to bright light. Cones help in
central and colour vision.
2. Rods: Rods are the nerve cells that are more sensitive to dim lights. Rodes help in
peripheral vision.
The message or sensation is then transferred to the brain along the optic nerve.

Figure: Representation of photoreceptor cells

Rod Cells
Rod cells are photoreceptor cells in the retina of the eye that are responsible for detecting light
and transmitting signals to the brain for the perception of vision, especially in low light
conditions. They contain a protein called rhodopsin that absorbs light and triggers a chain of
events leading to the activation of neural signals. Rods are more sensitive to light than cone
cells but do not distinguish color as well.

Cone Cells
Cone cells are photoreceptor cells in the retina of the eye that are responsible for color vision
and visual acuity (sharpness of vision). There are three types of cone cells, each containing a
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different photopigment sensitive to different wavelengths of light (red, green, and blue), which
allow for the perception of color. Cones are less sensitive to light than rod cells but provide
better visual acuity and color discrimination. They are concentrated in the fovea, the central
part of the retina responsible for detailed and sharp vision.

Architecture
Rod and cone cells have a similar basic structure, but there are some differences that are crucial
for their different functions.

Figure: Representing rod and cone cells

Both types of cells have a photoreceptor outer segment that contains the photopigment
(rhodopsin in rods and photopigments in cones) that absorbs light and triggers a change in
membrane potential. The inner segment contains the cell's organelles, including the nucleus
and mitochondria.
The major difference between rod and cone cells is their shape. Rod cells are elongated
and cylindrical, while cone cells are shorter and more conical in shape. This difference in shape
affects the distribution of photopigments and the number of synaptic contacts with bipolar and
ganglion cells, which transmit the signals to the brain. Rod cells have a single long outer
segment, while cone cells have several shorter segments.
Another difference between the two types of cells is the distribution of their synaptic
contacts with bipolar cells. Rod cells make synapses with one bipolar cell, while cone cells
synapse with one of several bipolar cells. This difference in synapse distribution is critical for
the different functions of rod and cone cells in vision.

2.2.2 Optical Corrections

Optical corrections refer to devices or techniques used to improve or correct vision
problems caused by a refractive error in the eye. Refractive errors occur when light entering
the eye is not properly focused on the retina, leading to blurred vision. There are several types
of refractive errors, including:
• Myopia (nearsightedness): Light is focused in front of the retina, making distant objects
appear blurry.
• Hyperopia (farsightedness): Light is focused behind the retina, making near objects
appear blurry.
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• Astigmatism: Light is not focused evenly on the retina, leading to blurred or distorted
vision.
The most common optical corrections include:
1. Eyeglasses: Glasses with corrective lenses can be used to refocus light onto the retina,
improving vision.
2. Contact lenses: Corrective lenses in the form of contacts sit directly on the cornea and
work similarly to eyeglasses.
3. Refractive surgery: Surgical procedures, such as LASIK and PRK, can reshape the
cornea to correct refractive errors.
Optical corrections can greatly improve visual acuity and quality of life for people with
refractive errors. However, it is important to have regular eye exams to determine the
appropriate correction and monitor eye health.

2.2.3 Cataract

Figure: Representing cataract

A cataract is a clouding of the lens of the eye that affects vision. The lens, located
behind the iris and pupil, normally allows light to pass through to the retina and produces clear,
sharp images. However, as we age or due to other factors, the proteins in the lens can clump
together and cause the lens to become opaque, leading to vision problems.
Symptoms of a cataract include blurred or hazy vision, increased sensitivity to glare
and bright lights, faded or yellowed colors, and double vision in one eye. Cataracts can also
cause frequent changes in prescription for eyeglasses or contacts.
Cataract surgery is a common and safe procedure to remove the cloudy lens and replace
it with an artificial lens. The surgery is typically performed on an outpatient basis and most
people experience improved vision within a few days after the procedure.
In conclusion, cataracts can significantly affect vision, but surgical removal and
replacement with an artificial lens can restore clear vision and improve quality of life. Regular
eye exams can help detect cataracts early and prevent vision loss.

2.2.4 Lens Materials

The artificial lenses used in cataract surgery or for vision correction can be made of a variety
of materials, each with its own unique properties and benefits. The most common lens materials
include:
• Polymethyl methacrylate (PMMA): PMMA is a type of plastic that has been used for
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many years in artificial lenses. It is a durable and affordable material, but does not have the
ability to flex and adjust focus like the natural lens.
• Silicone: Silicone is a soft, flexible material that is resistant to cracking and breaking.
It is often used in phakic intraocular lenses (IOLs), which are implanted in front of the natural
lens.
• Acrylic: Acrylic is a lightweight, clear material that is similar in properties to PMMA.
It is often used in foldable IOLs, which can be inserted through a smaller incision.
• Hydrophobic acrylic: Hydrophobic acrylic is a type of acrylic material that has a special
surface treatment that helps to reduce glare and halos around lights.
• Hydrophilic acrylic: Hydrophilic acrylic is a type of acrylic material that is designed to
be more compatible with the natural fluid in the eye, reducing the risk of vision-threatening
complications.
The choice of lens material will depend on several factors, including the patient's individual
needs, the surgeon's preference, and the potential risks and benefits of each material. Your eye
doctor can provide guidance on which lens material may be best for you.

2.2.5 Bionic Eye or Artificial Eye

A bionic eye, also known as a retinal implant, is a type of prosthetic device that is
surgically implanted into the eye to help restore vision to people who have lost their sight due
to certain conditions such as retinitis pigmentosa or age-related macular degeneration.

Figure: Photo of a bionic eye

The device typically consists of a camera, a processor, and an electrode array that is attached
to the retina. The camera captures images and sends signals to the processor, which the
transmits electrical stimulation to the electrodes in the retina to stimulate the remaining healthy
cells and restore vision. The restored vision is not perfect, but it can help people with vision
loss to perform daily tasks more easily and safely.

Materials Used in Bionic Eye

The materials used in a bionic eye can vary depending on the specific device and manufacturer.
However, some of the common materials used in bionic eye technology include:
• Silicon or other semiconducting materials for the camera and the electrode array.
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• Biocompatible materials for the casing of the device and the electrode array, such a
titanium or titanium alloys, to minimize the risk of infection and rejection by the body.
• Conductive materials, such as platinum, iridium, or gold, for the electrodes in the array
to provide efficient electrical stimulation to the retina.
• Polymers, such as silicone or polyimide, for insulation and protection of the electrodes
and other components.
• Optical materials, such as glass or acrylic, for the lens of the camera.
• Biocompatible and flexible materials for the electrical connections between the camera
and the processing unit and between the processing unit and the electrode array.
In addition to these materials, advanced computer algorithms and machine learning techniques
are also used to improve the accuracy and reliability of the bionic eye technology.

Working of Bionic Eye

Figure: Representing working of a bionic eye

A bionic eye typically works by capturing images with a small camera and transmitting
the information to a processing unit that is attached to the eye. The processing unit then
converts the visual information into electrical signals and sends them to an electrode array that
is surgically implanted onto the retina. The electrodes stimulate the remaining healthy cells in
the retina, which then sends signals to the brain to create the perception of vision.
The restored vision is not perfect, but it can help people with vision loss to perform
daily tasks more easily and safely. The amount and quality of vision that can be restored varies
depending on the individual and the type of bionic eye being used. Some bionic eyes only
restore basic visual shapes and patterns, while others can provide more detailed vision.
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The bionic eye is powered by a battery that is typically implanted behind the ear. The
battery is recharged through a device that is held near the eye, which transmits power wirelessly
to the battery. The device is typically rechargeable and can be used for several years before it
needs to be replaced.
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2.3 Heart as a Pump System:

2.3.1. Architecture: The heart is a complex pump system that circulates blood throughout
the body.

Figure: Representing the chambers of heart

It consists of four chambers: the right atrium, the left atrium, the right ventricle, and the
left ventricle. Blood enters the right atrium from the body and is pumped into the right ventricle,
which then pumps the blood to the lungs for oxygenation. Oxygenated blood returns to the
heart and enters the left atrium, which pumps the blood into the left ventricle. The left ventricle
then pumps the oxygenated blood out to the rest of the body.
Between each chamber, there are one-way valves that ensure the blood flows in the
correct direction and prevent backflow. The heart is also surrounded by the pericardium, a sac
that contains a small amount of fluid and helps to protect and lubricate the heart as it beats.

The Heart Beat

The heart's pumping action is controlled by a complex network of electrical and chemical
signals, which generate the rhythm of the heartbeat.

Figure: Representation of electrical system of the heart

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An electrical stimulus is generated in a special part of the heart muscle called the sinus
node. It's also called the sinoatrial node (SA node). The sinus node is a small mass of special
tissue in the right upper chamber of the heart (right atrium). In an adult, the sinus node sends
out a regular electrical pulse 60 to 100 times per minute. This electrical pulse travels down
through the conduction pathways and causes the heart's lower chambers (ventricles) to contract
and pump out blood. The right and left atria are stimulated first and contract to push blood from
the atria into the ventricles. The ventricles then contract to push blood out into the blood vessels
of the body.

2.3.2 Electrical Signalling – ECG Monitoring and Heart Related Issues

Figure: ECG waves and their relation to heart nodes

The heart's pumping action is controlled by electrical signaling, which generates the rhythm of
the heartbeat. This electrical signaling can be monitored using an electrocardiogram (ECG),
which records the electrical activity of the heart and provides important information about the
heart's function.
An ECG measures the electrical signals produced by the heart as it beats and generates a trace
or waveform that reflects the electrical activity of the heart. This trace can be used to diagnose
heart conditions and monitor the heart's function.
Some common heart-related issues that can be diagnosed or monitored using an ECG include:
• Arrhythmias: Abnormalities in the heart's rhythm or rate can be detected using an ECG.
• Heart disease: Changes in the heart's electrical activity can indicate the presence of
heart disease, such as coronary artery disease or heart attacks.
• Heart attack: An ECG can help diagnose a heart attack by detecting changes in the
heart's electrical activity that indicate a lack of blood flow to the heart.
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Overall, the ECG is a useful tool for diagnosing and monitoring heart-related issues and helps
to provide important information about the heart's function and health.

2.3.3 Reasons for Blockages of Blood Vessels

Figure: (A) shows damage (dead heart muscle) caused by a heart attack, (B) shows the
coronary artery with plaque build-up and a blood clot

Blockages in blood vessels, also known as arterial blockages or atherosclerosis, can occur for
several reasons:
High cholesterol levels: Excessive amounts of low-density lipoprotein (LDL) cholesterol in
the blood can lead to the formation of plaque in the blood vessels, which can narrow or block
them.
High blood pressure: Over time, high blood pressure can cause damage to the blood vessels,
leading to the formation of plaque and blockages.
Smoking: Smoking can damage the inner walls of blood vessels and promote the build-up
of plaque, leading to blockages.
Diabetes: People with uncontrolled diabetes are at a higher risk of developing blockages in
their blood vessels, due to damage to the blood vessels from high levels of glucose.
Age: As people age, the blood vessels can become stiff and less flexible, increasing the risk
of blockages.
Genetics: Some people may be predisposed to developing blockages in their blood vessels due
to genetic factors.
Poor diet: A diet high in saturated fats, trans fats, and cholesterol can increase the risk of
developing blockages in the blood vessels.
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The blockages in blood vessels can have serious health consequences, such as heart attacks and
stroke. Maintaining a healthy lifestyle, including eating a healthy diet, exercising regularly,
and avoiding smoking, can help reduce the risk of developing blockages in blood vessels.

2.3.4 Design of Stents

Stents are small, metal mesh devices that are used to treat blockages in blood vessels. They are
typically used in procedures such as angioplasty, where a balloon catheter is used to open up a
blocked blood vessel and a stent is placed to keep it open.

Figure: Representing the working of balloon stent and self-expanding stent

The design of stents can vary depending on the type of stent and the specific medical condition
it is used to treat. Some common design features of stents include:
Shape: Stents can be designed in a variety of shapes, including cylindrical, helical, and
spiralled, to match the shape of the blood vessel and provide adequate support.
Material: Stents can be made of different materials, including stainless steel, cobalt
chromium, and nitinol (a type of metal that is flexible and can return to its original shape after
being expanded).
Coating: Stents can be coated with different materials to prevent blood clots from forming
and reduce the risk of restenosis (recurrent blockage of the blood vessel).
Expansion mechanism: Stents can be designed to expand in different ways, such as by
balloon inflation or self-expansion, depending on the type of stent and the specific medical
condition it is used to treat.

Overall, the design of stents plays an important role in their effectiveness and safety. Stents
must be designed to provide adequate support to the blood vessel, prevent restenosis, and
minimize the risk of complications such as blood clots.
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2.3.5 Pace Makers

A pacemaker is a small device that is surgically implanted in the chest to regulate the heartbeat.
It is used to treat heart rhythm disorders, such as bradycardia (a slow heartbeat) or arrhythmias
(abnormal heart rhythms), by delivering electrical impulses to the heart to regulate its rhythm.

Figure: Representing components of a pacemaker

The basic design of a pacemaker consists of:

Generator: The generator is the main component of the pacemaker and contains a battery
and electronic circuitry to generate and control the electrical impulses.
Leads: Leads are thin wires that connect the generator to the heart and carry the electrical
impulses from the generator to the heart.
Electrodes: The electrodes are located at the end of the leads and are used to deliver the
electrical impulses to the heart.

Pacemakers can be designed to work in different ways, including:

Single-chamber pacemaker: A single-chamber pacemaker delivers electrical impulses to
either the right atrium or the right ventricle of the heart to regulate its rhythm.
Dual-chamber pacemaker: A dual-chamber pacemaker delivers electrical impulses to both
the right atrium and the right ventricle of the heart to regulate its rhythm.
Biventricular pacemaker: A biventricular pacemaker delivers electrical impulses to both
ventricles of the heart to coordinate their contractions and improve heart function in people
with heart failure.
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Figure: Representing the different types of pacemakers

Construction of a Pacemaker
The construction of a pacemaker involves the use of high-quality materials and specialized
manufacturing processes to ensure their safety and reliability. Materials used in the
construction of pacemakers include:
Medical-grade plastics: Medical-grade plastics, such as polycarbonate, are used to
construct the exterior of the device and to provide insulation and protection for the internal
components.
Metals: Metals, such as stainless steel and titanium, are used in the construction of the leads
and electrodes to ensure their durability and long-lasting performance.
Electronic components: Electronic components, such as microprocessors, batteries, and
capacitors, are used to control the delivery of the electrical impulses and to provide power to
the device.
Adhesives: Adhesives, such as cyanoacrylate and epoxy, are used to secure the components
of the device and to provide insulation and protection for the internal components.

The manufacturing process for pacemakers includes multiple quality control measures to
ensure their safety and reliability. This includes testing of individual components and final
assembly testing to verify the proper operation of the device before it is released for use.

2.3.6 Defibrillators
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Figure: Representing defibrillator

A defibrillator is a medical device that delivers an electric shock to the heart to restore its
normal rhythm in cases of cardiac arrest or other life-threatening heart rhythm disorders.
Defibrillators can be external (placed on the chest) or internal (implanted within the body).

The basic design of a defibrillator consists of:

Power source: The power source, typically a battery, provides energy to deliver the electric
shock to the heart.
Electrodes: The electrodes are placed on the chest and deliver the electric shock to the heart.
Circuitry: The circuitry in the defibrillator controls the delivery of the electric shock,
including the timing, strength, and duration of the shock.
Display: A display on the defibrillator provides information about the heart rhythm, battery
life, and other relevant information.

Automated External Defibrillators

External defibrillators, also known as automated external defibrillators (AEDs), are designed
for use by laypeople and are commonly found in public places such as airports, shopping
centers, and schools. They are relatively simple in design and typically have voice prompts and
visual cues to guide the user through the process of delivering the electric shock.

Implantable Cardioverter Defibrillators

Internal defibrillators, also known as implantable cardioverter defibrillators (ICDs), are
surgically implanted within the body and are used to treat people with a high risk of sudden
cardiac arrest. They are typically more complex in design, including features such as
continuous monitoring of the heart rhythm, and automatic delivery of shocks when necessary.

Construction of defibrillators
The construction of defibrillators involves the use of high-quality materials and specialized
manufacturing processes to ensure their safety and reliability.
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Materials Used
Materials used in the construction of defibrillators include:
Medical-grade plastics: Medical-grade plastics, such as polycarbonate, are used to
construct the exterior of the device and to provide insulation and protection for the internal
components.
Metals: Metals, such as stainless steel and titanium, are used in the construction of the leads
and electrodes to ensure their durability and long-lasting performance.
Electronic components: Electronic components, such as microprocessors, batteries,
capacitors, and high-voltage transformers, are used to control the delivery of the electrical
impulses and to provide power to the device.
Adhesives: Adhesives, such as cyanoacrylate and epoxy, are used to secure the components
of the device and to provide insulation and protection for the internal components.

The manufacturing process for defibrillators includes multiple quality control measures to
ensure their safety and reliability. This includes testing of individual components and final
assembly testing to verify the proper operation of the device before it is released for use.

Basic Design
The basic design of a defibrillator consists of:
Power source: The power source, typically a battery, provides energy to deliver the
electrical impulses to the heart.
Electrodes: The electrodes are placed on the chest and deliver the electrical impulses to the
heart to restore normal rhythm.
Circuitry: The circuitry in the defibrillator controls the delivery of the electrical impulses,
including the timing, strength, and duration of the impulses.
Display: A display on the defibrillator provides information about the heart rhythm, battery
life, and other relevant information.

Artificial Heart
An artificial heart is a device that is designed to replace the functions of a damaged or failing
heart. It can be used as a temporary measure to support a patient while they are waiting for a
heart transplant, or as a permanent solution for people who are not eligible for a heart transplant.

Figure: Schematic representation of artificial heart

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There are two main types of artificial hearts:

1. total artificial hearts and
2. heart assist devices.
A total artificial heart is a self-contained device that completely replaces the functions of the
natural heart. It is used as a bridge to transplant, meaning it provides temporary support to a
patient while they are waiting for a heart transplant.
Heart assist devices, on the other hand, are devices that are surgically implanted into the heart
and work alongside the natural heart to support its functions. While these devices are still in
the early stages of development, they have the potential to greatly improve the survival and
well-being of people with heart disease.