BEN520- Fundamentals of Bioengineering

SPRING 2024

Lecture 1
Introduction: What Is Bioengineering?

Lecturer: Asst. Prof. Betul Gurunlu

22.02.2024
Course Book
• Bioengineering
Fundamentals, Ann
Saterbak, Ka-Yiu-San,
Larry V. McIntire,
Pearson
Syllabus
• Introduction to Engineering Calculations
• Foundations of Conservation Principles
• Conservation of Mass
• Conservation of Energy
• Conservation of Charge
• Conservation of Momentum
• Case Studies
After completing this lecture, you should be able
to do the following:
• Perform unit conversions to attain answers in the desired units.
• Distinguish between intensive and extensive properties and list examples of each
type.
• Define the physical variables commonly used in accounting and conservation
equations.
• Specifically, you should be familiar with mass, moles, and molecular weight; mass
and mole fractions; concentration and molarity; temperature; pressure; density;
force and weight; potential, kinetic, and internal energy; heat and work;
momentum; charge and current; and flow rates.
• Report answers with an appropriate number of significant figures.
• Adopt a methodology for solving engineering problems; the one described is
used to solve many example problems throughout this textbook.
• Begin to develop a sense for the types of engineering problems that bioengineers
address.
Content

• Definitions of Bioengineering
• Short history
• Engineering in modern medicine
• What is biomedical engineering?
• Biomedical engineering in the future
What is Bioengineering ?
• Bioengineering is the “biological or medical application
of engineering principles or engineering equipment –
also called biomedical engineering

• Relatively new field that solves biological problems that

have persisted throughout history.

• Recently, the practice of bioengineering has expanded

beyond large-scale efforts like prosthetics and hospital
equipment to include engineering at the molecular and
cellular level – with applications in energy and the
environment as well as healthcare.
Short history

• Just consider and think about the technological

development that has shaped your live in the
past 20-30 years ?

• Now think about your parent, how these

technologies made their life better ? Or worse ?
Some achievements by now

•Pregnancy tests from home

•Vaccines
•Inexpensive contact lens
•Artificial hips
•Ultrasound imaging
•Pumps for insulin
…and so on…
Life expectancy increased
How this happened ?

• People are living longer because they are not

dying in situations that were in the past fatal,
suck as child birth and bacterial infections.

• Bioengineering has contributed to this change

by producing methods (diagnostics and drugs)
that decreased the death rates in the past 200
years.
Cont..

• For example: Car crashes , people get severe

injuries and in order to be quickly treated they
must be correctly diagnosed.

• This is possible due to Ultra sound imaging and

quick treatment can be provided… eventually
patient survive..
Too many names..?

• As you read about the subject of biomedical

engineering, you will encounter a variety of names that
sound similar: bioengineering, biological engineering,
biotechnology, biosystems engineering, bioprocess
engineering, biomolecular engineering, and biochemical
engineering.

• Students of biomedical engineering need to approach

the terminology with care (and without assuming that
the person using the terminology has the same
definition that they do!).
Cont..

• Some departments are called Department of

Biomedical Engineering and others Department
of Bioengineering, but in most cases the
educational mission and research programs
associated with these departments are similar

• Read page 4: Box 1.1 Too many names?

What is then Biomedical engineering?
• New students to the field of biomedical engineering ask versions of this
question:

“What is biomedical engineering?”

• Often, they ask the question directly but, just as often, they ask it in indirect
and interesting ways. Some of the forms of this question that I have heard in
the past few years are:

• Do biomedical engineers all work in hospitals?

• Do you have to have an MD degree to be a biomedical engineer?
• How can I learn enough biology to understand biomedical engineering and
enough engineering to be a real engineer?
• Is biomedical engineering the same as genetic engineering?
• How much of biomedical engineering is biology, chemistry, physics, and
mathematics?
Engineering in modern medicine

• Life on earth has improved due to the

technological changes that started in the 20th
century.
• TV, computer, mobile phones, airplanes,
ATMs..influences our life fully…
• These developments may have good but as well
very bad effects on our life's…

• For example , mobile phones..? How ?

Historical Preview…
• 1953 DNA discovered
• 1970 first synthetic gene
• 1975 DNA recombination method
• 1977 first sequencing method
• 1982 first genetic animal
• 1990 THE HUMAN GENOME PROJECT
• 1995 PCR invented
• 2000 first HUMAN genome sequenced
• 2008 bacterial genome synthesized
• 2014-228000 human genomes sequenced
• 2015 – edited human embryos..
• 2016 gene therapy
• Next ??????
What is a microbiome ?

• The human microbiome (all of our microbes' genes) can be

considered a counterpart to the human genome (all of our
genes). The genes in our microbiome outnumber the genes in our
genome by about 100 to 1.

• Commonly known as microbiota..

Engineering connection to biology
• Biomedical engineers seek to understand human
physiology and to build devices to improve or
repair it…
• Our working definition of biomedical engineering
can start in an obvious place.
• According to the Merriam-Webster Dictionary:
• engineering noun:
– a) the application of science and mathematics by which
the properties of matter and the sources of energy in
nature are made useful to people;
– b) the design and manufacture of complex products.
• The work of engineers is often hidden from view of
the general public, occurring in laboratories, office
buildings, construction sites, pilot plants, and testing
facilities.

• This is true for biomedical engineering as well as civil

engineering and other engineering disciplines.

• Although the work might be hidden, the end result

is often visible and important (e.g., the Brooklyn
Bridge or the artificial heart; see Figure 1.5).
Biomedical engineering can be divided into sub disciplines
Biomedical engineering in the future

• As we know our life expectancy has increased dramatically during the

last 100 years. Much of this progress is because of success in the battle
with infectious diseases.
• In London, in 1665, 93% of deaths were the result of infectious disease,
whereas in the United States, only 4% of deaths were the result of
infectious disease in 1997.

• Engineers contributed significantly to this effort by developing

sanitation methods for cities, large-scale processes for manufacture of
vaccines and antibiotics, and delivery methods for drugs.
Biomedical engineers have developed a number of life-enhancing
and life-saving technologies. These include:

• Prosthetics, such as dentures and artificial limb replacements.

• Surgical devices and systems, such as robotic and laser
surgery.
• Systems to monitor vital signs and blood chemistry.
• Implanted devices, such as insulin pumps, pacemakers and
artificial organs.
• Imaging methods, such as ultrasound, X-rays, particle beams
and magnetic resonance.
• Diagnostics, such as lab-on-a-chip and expert systems.
• Therapeutic equipment and devices, such as kidney dialysis
and transcutaneous electrical nerve stimulation (TENS).
• Radiation therapy using particle beams and X-rays.
• Physical therapy devices, such as exercise equipment
and wearable tech.
Future….

• Nano-machines (enzymes as controled robots )

• Efficient fuel cells…alternative energy sourse
• Sequencing off everything living on earth…
• Technologies based on biosciences
• Microbiome enhancement…
• Personal drugs….
• ..
• Human cloning ????
Human cloning

• ???????

Maybe the methodology makes this idea possible but what about
other concerns ? Problems that may arise with it?
Instructional Objectives

On December 11, 1998, the National Aeronautics and Space The loss of the $193 million spacecraft resulted from an embarrassing
Administration launched the Mars Climate Orbiter, a spacecraft oversight during the transfer of information between the Mars
designed to function as an interplanetary weather satellite and a Climate Orbiter spacecraft team in Colorado and the mission
communications relay. It never reached its destination. navigation team in California.
• In calculating an operation
critical to maneuvering the
spacecraft properly into the
Mars orbit, one team used
British units while the other used
metric units.
• As a result, instead of the planned
140 kilometers (90 miles), the
Mars Climate Orbiter approached
the planet at an altitude of about
57 kilometers (35 miles),2 causing
it to either crash in the Martian
atmosphere or skip off into space.
• Although hundreds of millions of dollars were
lost and much hope for scientific advancement
was dashed in the failure of this mission, the
losses associated with mistakes of this nature
in the field of biomedical engineering could
be even greater, for human lives are involved.
If a bioengineer were to miscalculate the
tolerable toxic range of a drug because of unit
conversion, a physician could prescribe an
incorrect dosage and cause a patient to die.
With so much at stake, the importance of
learning basic concepts and giving meticulous
attention to applying them cannot be
overemphasized.
• A thorough understanding of the material
presented in this chapter is crucial to your
success throughout your bioengineering
career. This chapter is an overview of
principles and definitions that lay the
groundwork for problem solving in
bioengineering.
• In Section 1.6, we will demonstrate the
relevance of this introductory material in real-
life applications.
Physical Variables, Units,
and Dimensions

• Being able to measure and quantify physical variables

is critical to finding solutions to problems in biological
and medical systems. Most of the numbers
encountered in engineering calculations represent the
magnitude of measurable physical variables, which
are quantities, properties, or variables that can be
measured or calculated by multiplying or dividing
other variables.
• Examples of physical variables include mass, length,
temperature, and velocity. Measured physical variables
are usually represented with a number or scalar value
(e.g., 6) and a unit (e.g., mL/min).
Physical Variables, Units,
and Dimensions

• A unit is a predetermined quantity of a

particular variable that is defined by custom,
convention, or law. Numbers used in
engineering calculations must be given with
the appropriate units. For example, a
statement that “The total blood flow in the
circulation of an adult human is 5” is
meaningless, but “The total blood flow rate in
the
• circulation of an adult human is 5 L/min”
quantifies how much blood flows through the
adult circulatory system.
Physical Variables, Units, and Dimensions

• A mistake that beginning engineers often make

is to write variables without units. Students
sometimes claim that they can keep track of
the units in their heads and do not need to
write them down repeatedly. This attitude
leads to many mistakes when calculating
solutions, which can lead to significant
consequences, as in the Mars Climate Orbiter
incident. Experienced engineers rarely omit
units.
• The basis for measurement of seven physical
variables agreed upon internationally is given
in Table 1.1. These include length, mass, time,
electric current, temperature, amount of
substance, and luminous intensity.
 Physical Variables, Units, and Dimensions
• In engineering calculations, many
other physical variables such as force
or energy are commonly used. The
units of these variables can be
reduced to combinations of the seven
base quantities. In this textbook, the
term dimension can be thought of as
a generic unit of a physical variable,
which is not scaled to a particular
amount for quantitative purposes. The
dimensional quantities you will
encounter in this textbook are listed in
Appendix A. The symbols for the
dimensions are given in Table 1.1.
Unit Conversion
• As discussed in Section 1.2, measured physical
variables are usually represented by a number
and a unit. The two most commonly used
systems are the Système International d’Unités
(SI), or metric system, and the British, or English,
system.
• Engineers must be familiar with both systems,
since institutions use and publish data in both.
• Many of the physical variables frequently
encountered in bioengineering will be
discussed in detail in Section 1.5. The physical
variables and corresponding symbols used in
this text are listed in Appendix A.
Unit Conversion
• Unit conversion is the process by which the units associated with a physical
variable are converted to another set of units by using conversion factors.
Common unit conversions are summarized on the inside front cover and in
Appendix B.

• You probably already know some conversion factors, such as that 1 in. is
equal to 2.54 cm and 2.2 lbm is equal to 1 kg.
• To convert a quantity expressed in terms of one unit to its equivalent in
terms of another unit, multiply the given quantity by the conversion factor
(new unit/old unit). Just as you would reduce multiples of a number in
fractions, cancel out units. For example, you can convert the mass of the
standard man in the British system (154 lbm) to its equivalent in the SI
system:
Unit Conversion

Because the unit lbm is present in Conversion factors are also

both the numerator and the required to convert within a
denominator, they cancel out. system of units. For example,
Writing out the units of the within the British system, we
conversion factor is critical; if you convert the mass of a 2200@lbm
do not, you may incorrectly scale car to its equivalent in tons as
the physical variable of interest. follows:
Unit Conversion
• Within the SI system, we may convert the length of the average
adult’s femur, 430 mm, to its equivalent in meters:
 Unit Conversion
• A series of prefixes is used to indicate
multiples and submultiples of units in
the SI system (Table 1.2).
• The “m” preceding the “m” of
• meters indicates “milli-” or 10-3 of
the unit. Often, a series of two or
more conversion factors is required to
convert a value in a given set of units
to the desired one. In situations with
several conversions, it is even more
critical to write out the units.
Unit Conversion
• As an engineer, it is exceedingly important
for you to develop a sense of scale and to
be able to tell whether your answer is
reasonable (see Section 1.9).
• Developing a sense of the magnitude of
various physical variables is an
important goal.
• Tables 1.3–1.5 give ranges of pressure,
length, and current for up to 20 orders
of magnitude. Think about the types of
bioengineering problems in which you
are interested and what their scale is.
 Dimensional Analysis
• In high school algebra, you learned to
manipulate equations to solve for
unknown variables. Engineers employ
the same fundamental principle to
decipher very complex models and
equations. It is a tool to simplify
complicated bioengineering problems
into smaller, more comprehensible
basic tasks in order to find a solution.
Dimensional Analysis
Dimensional Analysis
Dimensional Analysis

• Dimensional analysis is an algebraic tool engineers use to manipulate the units in a

problem. Numerical values and their corresponding units may be added or subtracted
only if the units are the same.

• 5m-3m=2m
• whereas
• 5 m - 2 s = ??
• The units of meters and seconds are not the same, so equation [1.4- 2] cannot be
executed. On the other hand, multiplication and division always combine numerical values
and their corresponding units.
Dimensional Analysis

• Properly constructed equations representing general relationships

between physical variables must be dimensionally homogeneous; that
is, the dimensions of terms that are added or subtracted must be the
same, and the dimensions of the right-hand side of the equation must
be the same as those of the left-hand side.
• As an example, consider the equation developed by Pennes to relate
blood perfusion rate (V #/V[L-3Mt-1]) to volumetric heat transfer rate
to the tissues (J [L-1 Mt-3]) in the human forearm according to the
equation:
• where Cp[L2 t-2 T-1] is the heat capacity, Ta [T] is the arterial blood
temperature, and Tv [T] is the venous blood temperature. We can
confirm that the units on each side of equation [1.4-5] reduce to [L-1
Mt-3], and therefore the equation is dimensionally homogeneous:
Specific Physical Variables

• This section highlights physical variables commonly used to develop and solve systems by
means of accounting and conservation equations—concepts that are developed in the
remainder of the book. We also briefly introduce extensive and intensive properties and
scalar and vector quantities. The physical variables are defined and described in the
context of five complex engineering scenarios in Section 1.6.
Extensive and
Intensive Properties
• Physical properties can be classified as either extensive or
intensive. An extensive property is defined as a physical quantity
that is the sum of the properties of separate non-interacting
subsystems that compose the entire system.
• The numerical value of an extensive property depends on the size of
the system, the quantity of matter in the system, or the sample
taken. In trying to think about whether a physical property is
extensive or intensive, consider whether the physical property
would change if the system of interest is doubled or halved.
• If the physical property changes when the system is doubled or
halved, the property is extensive. Another characteristic of an
extensive property is that it can be counted.
• Later, you will learn that only extensive properties may be counted
in accounting and conservation equations. In this book, extensive
properties that are counted include total mass and moles;
individual species mass and moles; elemental mass and moles;
positive, negative, and net electrical charge; linear and angular
momentum; and total, mechanical, and electrical energy.
 Scalar and Vector Quantities
• Physical variables are either scalar or vector quantities. Scalar quantities can be
defined by a magnitude alone.
• A vector quantity must be defined by both magnitude and direction. The vector
must be defined with respect to a reference point to its origin, which can be done
by specifying an arbitrary point as an origin and using a coordinate system, such as
Cartesian (rectangular), spherical, or cylindrical, to Show the direction and
magnitude of the vector. To denote a vector quantity in this lecture, we use an
arrow above the variable or symbol that represents the quantity (e.g., v> for
velocity vector).
• Two types of vectors are especially important: position
and velocity. Position vectors describe the distance and
direction of an object’s location with respect to an
origin; velocity vectors describe the direction with
respect to an origin and the distance an object moves
per instantaneous time period. To find the magnitude
of a vector using the Cartesian system, take the square
root of the sum of the squares of each component.
For example, a (45 i > + 45 j > )@km/hr vector in a
rectangular coordinate system could describe a car that
moves east at 45 km/hr and north at 45 km/hr.
However, the same car can be described as moving
northeast at a constant 63.6 km/hr. Some examples of
scalar and vector quantities are listed in Table 1.8.
• Vectors can be multiplied in two different ways.
The scalar product (or dot product) of two
vectors is a scalar quantity, as the name
indicates. The scalar product is equal to the
product of the magnitudes of the two vectors
and the cosine of the angle between them:
• Note that if the two vectors are perpendicular, their scalar product is
zero. The scalar product is commutative, so A># B > = B ># A>.
• The vector product (or cross product) of two vectors is a vector
quantity perpendicular to the plane of the two original vectors. Its
direction can be found by the so-called right-hand rule. Its magnitude
is the product of the magnitudes of the two vectors and the sine of
the angle between them:
Engineering
Case Studies
 • Parkinson’s disease is a
disorder of the central
nervous system that
affects over million
Americans. It is
characterized by rigid
muscles, involuntary
tremor, and difficulty in
moving limbs.
Parkinson’s • The disease is caused by the
destruction of neurons that
Disease secrete dopamine, an
inhibitory neurotransmitter
that helps regulate the
excitation signals for
movement. The reduced level
of dopamine available in the
brain causes the feedback
circuits to work improperly,
producing the rigidity and
tremors associated with
Parkinson’s disease.
 Parkinson’s Disease

• A biotech company has developed a new drug

that has the potential to increase dopamine
availability in the brain for patients with
Parkinson’s disease. A potential medication
has been determined but has been tested
only in animal subjects, who have the drug
directly injected through a hole drilled in the
skull. This intracranial delivery is hardly a
feasible option for human clinical trials, since
Parkinson’s disease is chronic and the drug
will need to be continually administered
Parkinson’s Disease
• As bioengineering experts at this
company, you and your team are In this problem you need
to analyze which task to
accomplish first. Because

asked to formulate a delivery the method of

administering the drug
will affect how it is

mechanism with proper dosages so formulated, we will

decide upon the delivery
method first.

that the drug can go to human

clinical trials. You must determine the
appropriate dose and dosing interval
(i.e., how frequently the treatment In this section, we discuss
some tools to define this
problem, using the

needs to be administered) as well as weight

• Concentration and molarity
following concepts:
• Mass
• Moles

the most convenient, safe, and

• Mass and mole fraction
• Molecular weight and average
molecular

effective manner of drug delivery.

Parkinson’s Disease

• Since direct drug injection through the skull is not a

realistic option, other methods must be considered
(see box). Of these, only oral administration, which is
by far the most convenient and accepted method, is
feasible. The other routes require hospital settings
(intravenous, intramuscular), have problems with the
organ targeted for absorption (rectal, inhalation, and
topical), or can be interfered with by the symptoms of
Parkinson’s disease, such as tremors
(buccal/sublingual, subcutaneous). A drug taken orally
can be absorbed across the membranes of the
gastrointestinal tract into the patient’s bloodstream and
then into the targeted organ.
 • Drugs can be administered through
various routes:
• 1. Intravenous: delivered directly
into the bloodstream.
• 2. Intramuscular injection:
injected directly into the muscle.
• 3. Oral: taken through the mouth,
as with pills.
• 4. Buccal/sublingual:
dissolved from small tablets
held in the mouth or under
the tongue.
• 5. Rectal: administered by a
suppository or enema.
• 6. Subcutaneous: injected under
the skin, as with insulin.
• 7. Inhalation: contained in an
aerosol inhaled by the patient.
• 8. Topical: absorbed through the
skin.

Parkinson’s Disease
Parkinson’s Disease
• To reach the target organ
effectively, delivery must overcome
limitations involving drugs
administered orally, including the
first-pass effect, the effect of food
on the drug, and the toxic effect of
the drug on the gastrointestinal
system. However, in developing a
drug for
• patients with Parkinson’s
disease, the major obstacle
is creating a drug that will
cross the blood–brain
barrier to reach the brain.
Parkinson’s Disease

• The brain has a specialized barrier called the blood–brain

barrier, which consist of adjacent endothelial cells tightly
fused with one another so that permeability of drugs and
other molecules is significantly reduced. Designed to
protect the brain from harmful substances, the blood–
brain barrier severely restricts the transfer of high-
molecular-weight molecules and polar (lipid-insoluble)
compounds from the blood to the brain tissue. Lipid-
mediated transport is generally proportional to the lipid
solubility of the molecule, but is restricted to molecules
with a molecular weight lower than approximately 500
g/mol. Currently, 100% of large-molecule drugs and over
98% of small-molecule drugs do not cross the blood–brain
barrier. Drug design must recognize and work with this
constraint.
Parkinson’s Disease

• To determine the appropriate dose for the drug, you

must be comfortable wit unit conversion and with the
concepts of mass, moles, and molecular weight. Atomic
weight and molecular weight should be familiar terms.
• Atomic weight is the mass of an atom relative to 12-
carbon (an isotope of carbon with 6 protons and 6
neutrons), which has a mass with a magnitude of exactly
12. The periodic table lists atomic weights for all the
elements (Appendix C).
• The molecular weight (M [MN-1]) of a compound is the
sum of the atomic weights of the atoms that constitute
the molecules of a compound. The molecular weight of
a substance can be expressed in a number of units,
including daltons, g/mol, kg/kmol, and lbm/lb@mol.
The dalton is a unit used in biology and medicine and is
equivalent to g/mol.
Parkinson’s Disease

• One mole of a species in the SI system, designated g-mol,

is defined to contain the same number of molecules as
there are atoms in 12 grams of 12-carbon. This is
Avogadro’s number or 6.023 * 1023 molecules. The
British system uses a similar concept, but the basic mole
unit is lbm@mol. This is defined in an analogous manner:
• A lbm@mol is equal to the number of atoms in 12 lbm of
12-carbon. Because a lbm is larger than a gram, a
lbm@mol is approximately 450 times larger than a g-mol.
In general, you will use g-mol instead of lbm@mol. In fact,
if the units of a quantity are specified as mol, assume g-
mol. One way to think of a mole is as the amount of
species whose mass (in grams) is equal to its molecular
weight. For example, 1 g-mol of CO2 contains 44 g of
material, since the molecular weight of CO2 is 44 g/g-mol.
Parkinson’s Disease
• The amount of a material is usually expressed through the physical
variables of mass or moles. Both mass (m [M]) and moles (n [N]) are base
physical variables (Table 1.1). The mass is a measure of the amount of a
material, whereas the number of moles present in a sample is calculated.
The molecular weight of component A (MA) is related to the mass of
component A (mA) and the number of moles of component A (nA) as
follows:

• Common biological molecules vary widely in molecular weight. Appendix D

lists the molecular weight of common biological molecules (Table D.1).
 Solving
Systems of • Most of the problems presented in this text, as well as
those you will encounter in the field, involve solving for one
Linear or more unknown values. While systems limited to one or
two unknown variables often can be solved easily by hand,
Equations in solving more complicated systems can be considerably
more cumbersome.
MATLAB • However, for systems described by linear equations,
there are computational techniques that can be applied
to minimize tedious calculations by hand. The
computational tools described below can be applied only
to solving sets of independent, linear equations.
Solving
Systems of
Linear
Equations in
MATLAB
Solving Systems of Linear Equations in
MATLAB
• The use of computer software programs such as MATLAB makes
solving systems of linear equations relatively easy, since they are
designed to handle matrices and vectors. The discussion below
assumes some familiarity with MATLAB.
• A system of linear equations can be represented by a matrix equation.
Consider the following example with two linear equations and two
unknown variables:
Solving Systems of Linear Equations in
MATLAB
• This system of equations is represented by the following matrix
equation in the form

• where A is a 2 * 2 matrix and x and y are vectors. Such a matrix

equation is analogous to the following scalar equation:
• Such a matrix equation is analogous to the following scalar equation:
EXAMPLE 1.30 Using MAT LAB to Solve Three
Linear Equations
• where a and y are known quantities and x is the unknown variable. In
this equation, it is easy to solve for x by simple division:
EXAMPLE 1.30 Using MAT LAB to Solve Three
Linear Equations
EXAMPLE 1.30 Using MAT LAB to Solve Three Linear Equations
Methodology for Solving
Engineering Problems
• Developing a pattern or methodology for solving
engineering problems is important for consistency
and thoroughness. The application of accounting
and/conservation equations (discussed in Chapters
2–7) should be carried out in an organized manner;
this makes the solution easy to follow, check, and be
used by others.
• As a new engineer, you may find going through these
many steps tedious and excessive for seemingly simple
problems. However, when the level of difficulty
increases, having a method or process to fall back on
will be invaluable. Experienced engineers use most of
the steps below when solving real-world problems.
Methodology for
Solving
Engineering
Problems
1. Assemble.
2. Analyze.
3. Calculate
4. Finalize
Summary
END of the 1st
LECTURE