BIOMEDIACAL NOTE-2022

1. Definition of Biomedical Engineering and Define Development of Bioengineering?

Answer: Biomedical engineering: is a discipline that advances knowledge in engineering,
biology and medicine, and improves human health through cross-disciplinary activities that
integrate the engineering sciences with the biomedical sciences and clinical practice.
It includes:
1. The acquisition of new knowledge and understanding of living systems through the innovative
and substantive application of experimental and analytical techniques based on the engineering
sciences.
2. The development of new devices, algorithms, processes and systems that advance biology
and medicine and improve medical practice and health care delivery.
The term "biomedical engineering research" is thus defined in a broad sense: It includes not only
the relevant applications of engineering to medicine but also to the basic life sciences.
Development of Bioengineering:
Over the last few years there has been a major paradigm shift in both Europe and the United
States away from traditional schemes of health care towards health care systems which are much
more dependent on technology. This is true in terms of diagnosis (eg body scanners); treatment
(radiation therapy and minimal access surgery); and health care system integration (via
information technology).

As medical practice becomes more technologically based, a progressive shift is occurring in

industry to meet the demand. Developments in science and engineering are increasingly being
directed away from traditional technologies towards those required for health care in its widest
sense. Although in many countries there is a problem with escalating costs in the medical sector,
technology can contribute to economies because of falling costs of electronic/physics based
components relative to those for personnel, and because of technologically based screening
programs.

2. What are the Specialty Areas of biomedical engineering?

Answer: Some of the well-established specialty areas within the field of biomedical
Biomedical engineering are:
 bioinstrumentation,
 biomechanics,
 biomaterials,
 systems physiology,
 clinical engineering, and
 Rehabilitation engineering.
Bioinstrumentation is the application of electronics and measurement principles and
techniques to develop devices used in diagnosis and treatment of disease. Computers are
becoming increasingly important in bioinstrumentation, from the microprocessor used to do a
variety of small tasks in a single purpose instrument to the extensive computing power
needed to process the large amount of information in a medical imaging system.
 Biomechanics is mechanics applied to biological or medical problems. It includes the study
of motion, of material deformation, of flow within the body and in devices, and transport of
chemical constituents across biological and synthetic media and membranes.
Biomaterials describes both living tissue and materials used for implantation. Understanding
the properties of the living material is vital in the design of implant materials. The selection of
an appropriate material to place in the human body may be one of the most difficult tasks
faced by the biomedical engineer. Biomaterials must be nontoxic, no carcinogenic, chemically
inert, stable, and mechanically strong enough to withstand the repeated forces of a lifetime.
Systems physiology is the term used to describe that aspect of biomedical engineering in
which engineering strategies, techniques and tools are used to gain a comprehensive and
integrated understanding of the function of living organisms ranging from bacteria to humans.
Modeling is used in the analysis of experimental data and in formulating mathematical
descriptions of physiological events. In research, models are used in designing new
experiments to refine our knowledge.
Clinical engineering is the application of technology for health care in hospitals. The clinical
engineer is a member of the health care team along with physicians, nurses and other
hospital staff. Clinical engineers are responsible for developing and maintaining computer
databases of medical instrumentation and equipment records and for the purchase and use
of sophisticated medical instruments.
Rehabilitation engineering is a new and growing specialty area of biomedical engineering.
Rehabilitation engineers expand capabilities and improve the quality of life for individuals with
physical impairments. Because the products of their labor are so personal, often developed
for particular individuals or small groups, the rehabilitation engineer often works directly with
the disabled individual.

3. Where do they Work?

Answer: Biomedical engineers are employed in industry, in hospitals, in research facilities of
educational and medical institutions, in teaching, and in government regulatory agencies. They
often serve a coordinating or interfacing function, using their background in both the engineering
and medical fields. In industry, they may create designs where an in-depth understanding of living
systems and of technology is essential. Government positions often involve product testing and
safety, as well as establishing safety standards for devices. In the hospital, the biomedical
engineer may provide advice on the selection and use of medical equipment, as well as
supervising its performance testing and maintenance. They may also build customized devices
for special health care or research needs. In research institutions, biomedical engineers
supervise laboratories and equipment, and participate in or direct research activities in
collaboration with other researchers with such backgrounds as medicine, physiology, and
nursing.
4. Career Preparation.
The biomedical engineer should plan first and foremost to be a good engineer. Beyond this, he or
she should have a working understanding of life science systems and terminology. Good
communications skills are also important, because the biomedical engineer provides a link among
professionals with medical, technical, and other backgrounds.
A top-quality biomedical engineer must have an excellent knowledge of physiology so that he/she
can make sound judgments in solving biomedical problems. When working in a specific area of
biomedicine, it is also necessary to know how disease alters functions, this is the field of
pathophysiology. With such knowledge, the biomedical engineer does not have to rely on others
for information about living organisms.
SLIDE-2
5. What NERVOUS SYSTEM?
Answer: The nervous system consists of the brain, spinal cord, sensory organs, and all of the
nerves that connect these organs with the rest of the body. Together, these organs are
responsible for the control of the body and communication among its parts. The brain and spinal
cord form the control center known as the central nervous system (CNS), where information is
evaluated and decisions made. The sensory nerves and sense organs of the peripheral nervous
system (PNS) monitor conditions inside and outside of the body and send this information to the
CNS. Efferent nerves in the PNS carry signals from the control center to the muscles, glands,
and organs to regulate their functions.
6. Discuss Nervous System Anatomy?
Answer: Nervous Tissue The majority of the nervous system is tissue made up of two classes of
cells: neurons and neuroglia. Neurons, also known as nerve cells, communicate within the body
by transmitting electrochemical signals. Neurons look quite different from other cells in the body
due to the many long cellular processes that extend from their central cell body. The cell body is
the roughly round part of a neuron that contains the nucleus, mitochondria, and most of the
cellular organelles. Small tree-like structures called dendrites extend from the cell body to pick up
stimuli from the environment, other neurons, or sensory receptor cells. Long transmitting
processes called axons extend from the cell body to send signals onward to other neurons or
effector cells in the body.
 There are 3 basic classes of neurons: afferent neurons, efferent neurons, and interneurons.
1. Afferent neurons. Also known as sensory neurons, afferent neurons transmit sensory signals
to the central nervous system from receptors in the body.
2. Efferent neurons. Also known as motor neurons, efferent neurons transmit signals from the
central nervous system to effectors in the body such as muscles and glands.
3. Interneurons. Interneurons form complex networks within the central nervous system to
integrate the information received from afferent neurons and to direct the function of the body
through efferent neurons.

Neuroglia:
Neuroglia, also known as glial cells, act as the “helper” cells of the nervous system. Each neuron
in the body is surrounded by anywhere from 6 to 60 neuroglia that protect, feed, and insulate the
neuron. Because neurons are extremely specialized cells that are essential to body function and
almost never reproduce, neuroglia are vital to maintaining a functional nervous system.

7. Write short note: (i) Brain, (ii) Spinal Cord, (iii) Sense Organs.
Answer:
Brain The brain, a soft, wrinkled organ that weighs about 3 pounds, is located inside the cranial
cavity, where the bones of the skull surround and protect it. The approximately 100 billion
neurons of the brain form the main control center of the body. The brain and spinal cord together
form the central nervous system (CNS), where information is processed and responses originate.
The brain, the seat of higher mental functions such as consciousness, memory, planning, and
voluntary actions, also controls lower body functions such as the maintenance of respiration,
heart rate, blood pressure, and digestion.
Spinal Cord
The spinal cord is a long, thin mass of bundled neurons that carries information through the
Vertebral cavity of the spine beginning at the medulla oblongata of the brain on its superior end
And continuing inferiorly to the lumbar region of the spine. The white matter of the spinal cord
Functions as the main conduit of nerve signals to the body from the brain. The grey matter of the
Spinal cord integrates reflexes to stimuli.
Sense Organs
All of the bodies’ many sense organs are components of the nervous system. What are known as
The special senses—vision, taste, smell, hearing, and balance—are all detected by specialized
Organs such as the eyes, taste buds, and olfactory epithelium. Sensory receptors for the general
Senses like touch, temperature, and pain are found throughout most of the body. All of the
Sensory receptors of the body are connected to afferent neurons that carry their sensory
Information to the CNS to be processed and integrated.
8. Type Functions of the Nervous System?
The nervous system has 3 main functions: sensory, integration, and motor.
1. Sensory. The sensory function of the nervous system involves collecting information from
sensory receptors that monitor the body’s internal and external conditions. These signals are then
passed on to the central nervous system (CNS) for further processing by afferent neurons (and
nerves).
2. Integration. The process of integration is the processing of the many sensory signals that are
passed into the CNS at any given time. These signals are evaluated, compared, used for decision
making, discarded or committed to memory as deemed appropriate. Integration takes place in the
gray matter of the brain and spinal cord and is performed by interneurons. Many interneurons
work together to form complex networks that provide this processing power.
3. Motor. Once the networks of interneurons in the CNS evaluate sensory information and decide
on an action, they stimulate efferent neurons. Efferent neurons (also called motor neurons) carry
signals from the gray matter of the CNS through the nerves of the peripheral nervous system to
effector cells. The effector may be smooth, cardiac, or skeletal muscle tissue or glandular tissue.
The effector then releases a hormone or moves a part of the body to respond to the stimulus.

SLIDE-3
9. Define Signals and information. Discuss classification of signal?
Answer: A signal is a function of one or several variables that carries useful information. A
signal is said to be
Biological, if it is recorded from a living system, and conveys information about the state or
behavior of that system. For example, the temperature record of a patient, the voltage recorded
by an electrode placed on the scalp, and the spatial pattern of X-ray absorption obtained from a
CT scan are biological signals. Signals can be either one-dimensional, if they depend on a single
variable such as time, or multidimensional if they depend on several variables such as spatial
coordinates.

Biomedical Signals are classified as follows:

1. Bioelectric signals: These signals are generated by the nerve and muscle cells. Their basic
source is the cell membrane which under certain conditions maybe excited to generate an action
potential. The electric field generated by the action of many cells constitutes the bioelectric signal.
The most common examples of bioelectric signals are the ECG (Electrocardiographic) and EEG
(Electroencephalographic) signals. (Link to amazon products for ECG and EEG)
2. Biomechanical signals: These signals are generated due to some mechanical function of a
physiological system. They include all types of motion and displacement signals, pressure, flow
signals etc. in the physiological system.
3. Bioacoustics signals: These signals are created by the physiological system in which either
flow of blood or air takes place. The flow of the blood in the heart as well as inspiration and
expiration of the lungs takes place accompanied with unique acoustic signals.
4. Bio-impedance signals: The impedance of the skin depends upon; the composition of the
skin, blood distribution and blood volume through the skin. The measurement of impedance helps
in finding the state of skin and functioning of various physiological systems. The voltage drop due
to the tissue impedance is a bio-impedance signal.
5. Biochemical signal: The signals which are obtained as a result of chemical measurements
from the living tissue or from samples analyzed in the laboratory. The examples of these include;
measurement of partial pressure of carbon-dioxide (pCO2), partial pressure of oxygen (pO2) and
concentration of various ions in the blood.
 6. Bio-optical signals: These signals are produced by the optical variation by the functioning of
the physiological system. The blood oxygenation can be determined by measuring transmitted
and reflected light occurring from the blood vessel.
7. Bio magnetic signals: Extremely weak magnetic fields are produced by various organs such
as the brain, heart and lungs. The measurement of these signals provides information which is
not available in other types of bio-signals such as bioelectric signals. A typical example is the
Magneto encephalography.

10. Define filter and discuss classification of filter?

Answer: A filter is a frequency selective network that passes a specified band of frequencies
and blocks signals of frequencies outside this band.

Classification of Filters
1. Low Pass Filter: The low pass filter only allows low frequency signals from 0 Hz to its cut-
off frequency, ƒc point to pass while blocking any higher frequency signals.

2. High Pass Filter: The high pass filter only allows high frequency signals from its cut-off
frequency, ƒc point and higher to infinity to pass through while blocking those any lower.

3. Band Pass Filter : The band pass filter allows signals falling within a certain frequency
band set up between two points to pass through while blocking both the lower and higher
frequencies either side of this frequency band.
4. Band Stop Filter : The band stop filter blocks signals falling within a certain frequency
band set up between two points while allowing both the lower and higher frequencies
either side of this frequency

11. Discuss Stages in biomedical signal processing?

Answer: In a typical biomedical application, signal processing may include four stages (see
Figure 1): data acquisition, signal conditioning, feature extraction, and decision making. The goal
of data acquisition is to capture the signal and encode in a form suitable for computer processing.
At this stage, the main concern is to avoid losing information about the signal. The goal of signal
conditioning is to eliminate or reduce extraneous components such as noise from the signal.
Often, this done using linear filters, sometimes in combination with nonlinear operators. A major
theme of this course is how to design filters that best separate signal from noise. Feature
extraction means identifying and measuring a small number of parameters or features that best
characterize the information of interest in a signal.

Data Acquisition
The goal of data acquisition is to capture a signal and encode in a form suitable for computer
processing with minimum loss of information. Data acquisition typically consists of three stages:
transduction, analog conditioning, and analog-to-digital conversion.

Transduction is the conversion from one form of energy to another. In present technology, the
only form of energy suitable for encoding into a computer is electrical energy, therefore signals
need to be converted to analog voltages whose waveforms are ideally the same as those of the
 original signals. For example, we use a microphone to transduce an acoustic signal, or an electric
thermometer to measure temperatures.
. The second stage of data acquisition, analog signal conditioning, usually consists of amplifying
and filtering the analog signal measured with a transducer. Because the purpose of this stage is
to rovide a good match between the typically low-amplitude, wide-bandwidth transducer signals
and the analog-to-digital (A/D) converter, conditioning is best understood after studying A/D
conversion.

Analog-to-digital converter is a device that transforms a continuous-time signal measured with a

transducer into a digital signal that can be represented in a computer. Conceptually, it can be
divided into a series of two operations:
Sampling, in which the continuous-time, analog signal is converted into one that is only defined
for discrete times, but whose amplitude can take arbitrary values, and
Quantization, in which a continuous-amplitude signal is converted into a digital signal that can
only take a finite set of values. The sampling operation is particularly critical if we want to avoid
loss of information in the conversion.

12. Signal processing selectively eliminates information.

Answer: More often than not, a signal conveys irrelevant information as well as the information of
interest. For example, the electroencephalogram (EEG) recorded from the scalp of a volunteer
may be contaminated by the electrophysiological activity of the heart and the ubiquitous 50-Hz
power-line signal. What constitutes information of interest depends on the specific application.
For example, a speech signal contains both linguistic information (what was said) and information
about the speaker (who said it).
The purpose of signal processing is to selectively eliminate irrelevant information from a signal so
as to make the information of interest more easily accessible to a human observer or a computer
system. The reason for this negative definition is that it is never possible to add information to a
given signal, only to eliminate it.
 DSP PART
1. Define signal and system?
Answer:
2. Discuss advantage of digital signal processing over analog signal processing?
Answer:

3. (a) Multichannel & multidimensional signal.

(b) Continues time and discreet signal.
(c) Discrete & continuous valued signal.
(d) Random and deterministic signal.
Answer:
5. What is signal processing? What type of signal processing?
Ans:
6. Define analog signal and digital signal processing. Discuss advantage and disadvantage
and explain with block diagram.
Answer: Analog signals are a representation of time varying quantities in a continuous signal.
Basically, a time variance is presented in a manner in which some sort of information is passed
using various types of methods, including electrical, mechanical, hydraulic, or pneumatic
systems.
 7. What is quantization and quantization error? Explain with example.

Quantization

The digitization of analog signals involves the rounding off of the values which are approximately equal to
the analog values. The method of sampling chooses a few points on the analog signal and then these
points are joined to round off the value to a near stabilized value. Such a process is called as
Quantization.

Quantization Error: For any system, during its functioning, there is always a difference in the values of
its input and output. The processing of the system results in an error, which is the difference of those
values.

The difference between an input value and its quantized value is called a Quantization Error. A Quantizer
is a logarithmic function that performs Quantization rounding off the value rounding off the value. An
analog-to-digital converter (ADC) works as a quantizer.

The following figure illustrates an example for a quantization error, indicating the difference between the
original signal and the quantized signal.

8. What is sampling rate and signal reconstruction?

Sampling: is defined as, “The process of measuring the instantaneous values of continuous-time
signal in a discrete form.”
Sample is a piece of data taken from the whole data which is continuous in the time domain.
 When a source generates an analog signal and if that has to be digitized, having 1s and 0s i.e.,
High or Low, the signal has to be discretized in time. This discretization of analog signal is called
as Sampling.
The following figure indicates a continuous-time signal x tt and a sampled signal xs tt.
When x tt is multiplied by a periodic impulse train, the sampled signal xs tt is obtained.

Sampling Rate

To discretize the signals, the gap between the samples should be fixed. That gap can be termed as
a sampling period Ts.
Sampling Frequency = 1/Ts = fs

Where,
 Ts is the sampling time
 fs is the sampling frequency or the sampling rate
Sampling frequency is the reciprocal of the sampling period. This sampling frequency, can be simply
called as sampling rate. The sampling rate denotes the number of samples taken per second, or for a
finite set of values.
For an analog signal to be reconstructed from the digitized signal, the sampling rate should be highly
considered. The rate of sampling should be such that the data in the message signal should neither be lost
nor it should get over-lapped. Hence, a rate was fixed for this, called as Nyquist rate.
Signal reconstruction

In signal processing, reconstruction usually means the determination of an original continuous signal
from a sequence of equally space samples.