MEDICAL .pptx

EC8073 – MEDICAL
ELECTRONICS

UNIT I ELECTRO-PHYSIOLOGY AND BIO-
POTENTIAL RECORDING
The origin of Bio-potentials; biopotential
electrodes, biological amplifiers, ECG, EEG,
EMG, PCG, lead systems and recording
methods, typical waveforms and signal
characteristics.

The Resting
Membrane Potential
Lecture 4

Biolelectric Potential
• Communication within neuron
– electrical signal
• electric current = movement of electrons
• Bioelectric: movement of ions ~

Ion Distribution
• Particles / molecules
– electrically charged
• Anions
– negatively charged
• Cations
– positively charged ~

• Anions (-)
Large intracellular proteins
Chloride ions Cl-
• Cations (+)
Sodium Na+
Potassium K+ ~
Ion Distribution

Resting Membrane Potential
Membrane
Na+ Cl-
A- K+
outside
inside

• more negative particles in than out
• Bioelectric Potential
– like a battery
• Potential for ion movement
– current ~
Membrane is polarized

Resting Membrane Potential
Membrane
outside
inside
+ + + + + + + + + + +
-
-
-
-
-
-
-
-
-
-
-

INSIDE
POS
NEG
Bioelectric Potential
OUTSIDE

Membrane Potential
• Net bioelectric potential
for all ions
• Balance of both gradients
concentration & electrostatic
• Units = millivolts (mV)
• Vm = -65 Mv
– given by Goldman equation ~

i
cl
i
Na
i
K
o
cl
o
Na
o
K
m
Cl
P
Na
P
K
P
Cl
P
Na
P
K
P
ZF
RT
V
]
[
]
[
]
[
]
[
]
[
]
[
ln 








Membrane Potential:
Goldman Equation
• P = permeability
• Net potential movement for all ions
• known Vm:Can predict direction of movement
of any ion ~

Differential Amplifiers
• Infinite Input impedance thus current passes from R3 to
R4 and from R1 to R2
R2
0
0
2
0
4
0
1
2
3
2
2
1
1
4
3
2
1
4
3
2
1
















I
I
I
I
R
A
R
A
I
R
A
E
R
A
E
I
R
A
V
I
R
A
E
I
output
-
+ Voutput
R1 A
R3
Voutput
I4
I3
R1 R2
I1 I2
R4
Vinput
E1
E2
R4
R3
E1
E2
Book Assumes: Vinput = E2-E1
And R1 =R3 and R2=R4
1
2
1
2
)
1
2
(
2
1
1
2
1
2
2
1
2
2
2
1
2
2
2
2
0
1
2
0
2
0
1
2
1
2
1
2
1
1
1
2
2
1
2
1
1
0
2
1
1
R
R
E
E
V
E
E
R
R
V
R
V
R
E
R
E
AR
AR
R
E
AR
AR
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E
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A
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A
E
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A
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E
AR
AR
R
V
R
E
R
V
AR
AR
R
E
R
A
V
R
A
E
R
A
V
R
A
E
output
output
output
output
output
output
output













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
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


 







A
A

Advantages of Differential Amplifier
• In differential mode you can cancel noise
common to both input signals
R2
-
+ Voutput
R1 A
R3
R4
E2
E1
1V
3V
2V

Instrumentation Amplifier
• Give you high gain and high-input impedance.
• Composed of 2 amplifiers in noninverting format and a 3rd amplifier as a differential amplifier
+
-
R2
Vinput
E1
E1
R5
-
+
R4
R7
R6
+
-
E2
R1
E2
R3 Voutpt

















4
5
1
1
2
2
7
5
;
6
4
;
3
2
R
R
R
R
Vinput
Voutput
R
R
R
R
R
R

Derivation of Gain for Instrumentation Amplifier step 1
+
-
E2
R1
E2
R3
E1
E3
E3
R1 R3
I1 I2
E1 E2
I1
I2
1
1
3
1
1
3
2
3
2
1
3
1
1
3
2
3
2
3
1
3
2
1
3
1
3
1
2
1
2
3
1
3
3
3
2
1
2
1
2
1
E
R
R
R
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E
E
E
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I
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









Derivation of Gain for Instrumentation Amplifier
step 2
+
-
R2
E1
E1
R1
E2
E4
R1 R2
I1 I2
E2 E1
I1
I2
2
1
2
1
2
1
1
4
1
1
2
2
1
2
1
4
1
2
2
2
1
1
4
1
4
1
1
1
1
2
2
2
2
4
1
1
1
2
2
1
E
R
R
R
R
E
E
E
R
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I
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


E4

step 3
R5
-
+
R4
R7
R6
Voutput
E4
E3
Voutput
I7
I6
R4 R5
I4 I5
E4
R7
R6
E3
Book Assumes R4 =R6 and R5=R7
0
I4
I5
I6
I7
7
6
5
4
7
6
5
4
5
0
7
0
4
3
6
3
5
4
4
I
I
I
I
R
A
R
A
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A
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
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4
5
4
3
4
)
4
3
(
5
4
5
4
5
3
4
5
5
3
4
5
5
3
5
0
4
3
4
5
4
5
4
4
4
5
5
4
5
4
4
R
R
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V
R
V
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E
R
R
V
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AR
AR
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AR
AR
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A
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AR
AR
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V
R
E
R
V
AR
AR
R
E
R
V
A
R
A
E
output
output
output
output
output
output
A
A

step 4
  







4
5
4
3
R
R
E
E
Voutput
2
1
2
1
2
1
1
4 E
R
R
R
R
E
E 














1
1
3
1
1
3
2
3 E
R
R
R
R
E
E 








Book Assumes R3 =R2
 




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

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4
5
1
1
2
2
1
2
4
5
1
2
1
1
2
1
1
2
1
1
2
2
4
5
1
2
2
1
2
1
1
1
2
1
1
1
2
2
1
1
2
1
1
2
2
3
R
R
R
R
E
E
V
R
R
R
R
R
R
E
R
R
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V
R
R
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E
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R
E
R
R
E
V
E
R
R
R
R
E
E
output
output
output
Step1
Step2
Step3

Example of Instrumentation
Amplifier
• Find the gain of the previous instrumentation
amplifier if R2 = 10K; R1=500; R4 = 10K ;
R5 = 100K 
 
410
10
100
1
5
.
0
10
*
2
1
2
4
5
1
1
2
2
1
2



















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


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
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




K
K
K
K
E
E
V
R
R
R
R
E
E
V
output
output

Problem 1
• Design a differential amplifier where the
feedback resistors are equal and the input
resistors are equal. The gain should be equal
to 10. One input voltage is 1 V and the second
input voltage is 2 V. What is the output
voltage?
• If the input resistance is 4 K what is the
feedback resistance?

Solution 1
V
V
V
V
V
V
V
V
V
V
out
out
out
10
)
1
2
(
*
10
1
2
10
1
2















K
K
R
K
R
R
R
V
V
f
f
in
f
in
out
40
4
*
10
4
10

Problem 2
• An instrumentation amplifier has a gain of 20.
Using the schematic discussed earlier in the
lecture, R5 = R7; R4=R6; R2 = R3.
• If R5 = 10K and R4 = 1K. The current
across R2 is 4 mA and Vinput1 is 1V. Vout1 = -2V.
– Draw Schematic
– Find R2 & R1.

Solution 2
+
-
R2
Vinput
E1
E1
R5
-
+
R4
R7
R6
+
-
E2
R1
E2
R3 Voutpt
Vout1
Vin1
IR2






 750
4
3
4
)
2
(
1
2
2
1
1
mA
V
mA
V
V
I
V
V
R
R
out
in

Solution 2 cont











































K
R
R
K
R
K
K
K
R
R
R
R
R
Vinput
Voutput
R
R
R
R
R
R
5
.
1
1
1
5
.
1
1
1
1
5
.
1
2
10
20
1
10
1
1
)
750
(
2
20
20
4
5
1
1
2
2
7
5
;
6
4
;
3
2

Review for Exam 1
• Review all Homework Problems
• Review Wheatstone Bridge Lab & Amplifier
Lab
• Review Studio exercises (precision & accuracy
and aliasing exercises)
• Bring Calculators
• Closed book
• Equation sheet given previously will be given
out at exam

Function of EEG
• The EEG uses highly conductive silver electrodes coated with
silver-chloride and gold cup electrodes to obtain accurate
measures… use impedance device to measure effectiveness,
resistance caused by dura mater, cerebrospinal fluid, and
skull bone
• Monopolar Technique : the use of one active recording
electrode placed on area of interest, a reference electrode in
an inactive area, and a ground
• Bipolar Technique : the use of two active electrodes on
areas of interest
• Measures brain waves (graphs voltage over time) through
electrodes by using the summation of many action potentials
sent by neurons in brain. Measured amplitudes are lessened
with electrodes on surface of skin compared to
electrocorticogram

Sodium-Potassium Pump
• The mechanism within neurons that creates action
potentials through the exchange between sodium
and potassium ions in and out of the cell
• Adenosine Triphosphate (ATP) provides energy for
proteins to pump 300 sodium ions per second out of
the cell while simultaneously pumping 200
potassium ions per second into the cell
(concentration gradient)
• Thus making the outside of the cell more positively
charged and the neuron negatively charged
• This rapid ionic movement causes the release of
action potentials

Alpha Wave
• Characteristics:
- frequency: 8-13 Hz
-amplitude: 20-60 µV
• Easily produced when quietly sitting in relaxed
position with eyes closed (few people have
trouble producing alpha waves)
• Alpha blockade occurs with mental activity
-exceptions found by Shaw(1996) in the case
of mental arithmetic, archery, and golf putting

Beta Waves
-frequency: 14-30 Hz
-amplitude: 2-20 µV
• The most common form of brain waves. Are
present during mental thought and activity

Theta Waves
-frequency: 4-7Hz
-amplitude: 20-100µV
• Believed to be more common in children than
adults
• Walter Study (1952) found these waves to be
related to displeasure, pleasure, and drowsiness
• Maulsby (1971) found theta waves with
amplitudes of 100µV in babies feeding

Delta Waves
-frequency: .5-3.5 Hz
-amplitude: 20-200µV
• Found during periods of deep sleep in most
people
• Characterized by very irregular and slow wave
patterns
• Also useful in detecting tumors and abnormal
brain behaviors

Gamma Waves
-frequency: 36-44Hz
-amplitude: 3-5µV
• Occur with sudden sensory stimuli

Sleep and The EEG
• Different stages of sleep and their respective brain waves:
– Stage 1: Low voltage random EEG activity (2-7 Hz)
– Stage 2: Irregular EEG pattern/negative-positive spikes (12- to 14- Hz)
– Also characterized with sleep spindle and K-complexes that could occur every few seconds.
– Stage 3: Alternative fast activity, low/high voltage waves and high
amplitude delta waves or slow waves (2 Hz or less).
– Stage 4: Delta waves
– Stage REM (Rapid eye Movement): “episodic rapid eye movements,” low v
voltage activity.
– Stage NREM: All stage combined, but not including REM or stages that may
contain REM.
• The K-complex occurs randomly in stage 2 and stage 3
– The K complex is like an awaken state of mind in that is associated with a
response to a stimulus that one would experience while awake.

EEG brain waves in the Sleep
Cycle

• A1-lefrt ear A2-right ear
Fp-frontal pole leads
F-frontal leads
P-parietal leads
C-central leads
T-temporal leads
O-occipital leads

INTRODUCTION
• Electromyogram (EMG) is a technique for
evaluating and recording the activation signal of
muscles.
• EMG is performed by an electromyograph,
which records an electromyogram.
• Electromyograph detects the electrical potential
generated by muscle cells when these cells
contract and relax.

INTRODUCTION Contd.
EMG Apparatus Muscle Structure/EMG

ELECTRICAL CHARACTERITICS
• The electrical source is the muscle membrane
potential of about -70mV.
• Measured EMG potentials range between
< 50 μV up to 20 to 30 mV, depending on the
muscle under observation.
• Typical repetition rate of muscle unit firing is
about 7-20 Hz.
• Damage to motor units can be expected at
ranges between 450 and 780 mV

ELECTRODE TYPES
Intramuscular -
Needle Electrodes
Extramuscular - Surface
Electrodes

EMG PROCEDURE
• Clean the site of application
of electrode;
• Insert needle/place surface
electrodes at muscle belly;
• Record muscle activity at rest;
• Record muscle activity upon
voluntary contraction of the
muscle.

EMG Contd.
• Muscle Signals are
Analog in nature.
• EMG signals are also
collected over a
specific period of
time.
Analog Signal

EMG Contd.
EMG processing:
Amplification
& Filtering
Signal pick up
Conversion of Analog
signals to Digital signals
Computer

APPLICATION OF EMG
• EMG can be used for diagnosis of Neurogenic
or Myogenic Diseases.
• You tube link of EMG

CONCLUSION
• Variability/Uncertainity in movement is higher in
normals as compared to individuals with Stroke.
• This variability could be correlated with adaptability
in movement which is decreased upon nervous
system damage in Stroke.
• Large data is required to generalize these results.

INTRODUCTION
Graphic record of the heart sounds is called phonogram.
Uses a phono-catheter, device similar to the conventional
catheter, with a microphone at the tip.
Picks the different heart sounds, filter out the heart sounds
and display them or record them.
heart sounds are acoustic phenomena resulting from the
vibrations of the cardiac structures.

Acoustic events of heart can be divided into
two categories
Heart sounds
Heart sounds have a transient character and
are of short duration.
Caused mainly due to the opening and closing of
valves.
Heart Murmurs
Heart murmurs have a noisy characteristics and
last for a longer time.
Caused by the turbulent flow of blood in the
heart to the large vessels.

Heart sounds 4 types
Valve closure sounds
Ventricular filling sounds
Valve opening sounds
Extra cardiac sounds

Valve
Closure
Sounds
occurs in the beginning of the
systole (first heart sound)
and the beginning of the diastole
(second heart sound)
first heart sound is due to closure
of mitral and tricuspid valves.
second heart sound is due to
closure of the aortic and
pulmonary valves.

Ventricular
filling
sounds
occurs either at the period of rapid filling
of the ventricles (third heart sound)
OR
during the terminal phase of ventricular
filling i.e. atrial contraction caused by the
sudden distention of the ventricular
wall
sounds normally are inaudible

Valve
opening
sounds occurs at the time
of
opening of the ventricular
valves
and
semi-lunar valves

Extra
Cardiac
sounds occurs in the mid or late systole or
early diastole
caused by the thickened pericardium
which limits ventricle distensibility

FREQUENCY
All heart sounds and murmurs lie between
0 to 1000Hz.
Further divided into low, medium, high-pitch
categories depending upon the frequency that
predominates
the low ranges from 10-60Hz and represents third
and fourth heart sounds.
the medium ranges from 60-150Hz and represents
first and second heart sounds.
the high ranges from 150-1000Hz and represents
snaps, clicks and diastolic murmurs of the aortic
and pulmonary insufficiency.

ORIGIN
OF
HEART
SOUNDS
Four sounds occur in the complete heart cycle
First heart cycle produced by the sudden closure of
the mitral and tricuspid valves associated with
myocardial contraction.
Second heart cycle produced due to the vibration set
up by the closure of the semi-lunar valves i.e.
closure of aortic & pulmonary
Third heart cycle arises as the ventricles relax and the
internal pressure drops well below the pressure in
atrium.
Meanwhile the atrio-ventricular valves open and the
blood has a rapid movement into the relaxed
ventricular chambers.
Fourth heart cycle also called atrial sound, caused by
the accelerated flow of the blood into the ventricles
or due to the atrial contraction.

First
heart
cycle
Timing : the low frequency vibration
occurs approx. 0.05 sec after the onset
of the QRS complex of ECG.
Duration : the first heart sound lasts for
0.1 to 0.12 sec
Frequency : the first heart sound ranges
from 30-50 Hz.
Auscultatory Area : the first heart sound
is the best heard at the apex of the mid
pericardium.

Second
heart
cycle
Timing : starts approx. 0.03-0.05sec
after the end of the T wave of ECG.
Duration : this lasts for 0.08-0.14sec
Frequency : up to 250Hz
Auscultatory Areas : best heard in the
aortic and pulmonary areas.

Third
heart
cycle
Timing : the third starts at 0.12-
0.18sec after the onset of the second
heart sound.
Duration : lasts for 0.04-0.08sec
Frequency : last approx. 10-100Hz
Ascultatory Areas : best heard at the
apex and the left lateral position after
lifting the legs.

Fourth
heart
cycle
Timing : approx. 0.12-0.18sec after
the onset of P wave.
Duration : lasts for 0.03-0.06sec.
Frequency : 10-50Hz.
Ascultatory Area : usually inaudible due
to extreme low frequency.

Transduction
of
heart
sound
Derivation of sounds and murmurs can
be done using stethoscope or by the
transduction of the sounds to
electric signals in the chest.
Captured as the sounds are well
conducted from the heart to the
surface of the chest when the
myocardial tissue lies in the close
proximity to the chest wall.

Recording
set
up
sounds are captured by the microphone
fastened to the chest wall by a
adhesive strip.
sounds are converted to electrical signals
by a transducer, amplified by a
phonocardiograph preamplifier
followed by suitable filters and recorder.
electrodes are also placed on the limbs
to pick up the electrical activity of the
heart and these signals are too amplified
and recorded.
this recorded ECG is used as a
reference for the PCG.

Phonocardiograph preamplifier
First stage has the amplification of about 20, while the second stage has
the amplification of 50. Therefore expected gain is 1000.
Continuous variation of the gain can be achieved through a 22kohm
potentiometer.
the shunt capacitance 0.02uF and feedback loop capacitance 68uF of the
second stage limit the response from 10Hz to 1000Hz

FILTERS
FOR
PHONOCARDIOGRAM
High pass filters
having a gradual
slope of
attenuation are
needed since band
pass filters with
sharp cutoff
produce transients
and masks the
splitting heart
sounds.

In the case of
murmurs,
where greater
selectivity is
required, high
pass filter with
sharp slope is
required.

MEDICAL
APPLICATIONS
Valvular Lesions
Most of the
valvular lesions
results from the
rheumatic fever.
Rheumatic fever
is an autoimmune
or allergic in
which the heart
valves are likely to
be damaged.
It can be detected
by
phonocardiograph.
The valvular
lesions caused

The
Murmur
of
the
Aortic
Stenosis
In aortic stenosis the blood is ejected from the left
ventricles through the small opening of the
aortic valve.
Because of the resistance to ejection, pressure increases
as high as 350mm of Hg.
This causes turbulent flow of blood flow.
This turbulent blood impinging the aortic valve causes
intense vibration, it produce a large murmur that
could be heard several feet away from the patient.

The Murmur of the Aortic Regurgitation*
In aortic regurgitation, no sound is heard during
the systole, but during the diastole blood flows
backward from the aorta into the left ventricles,
causing a "blowing" murmur, the sound is not as high
that of aortic stenosis.
This is produced during the valves are damaged.
*Regurgitation : backward flow of blood through a defective heart

The Murmur of the mitral regurgitation
In mitral regurgitation, the blood flows backward
through the mitral valve during the systole.
This produces sound during the systole.

The Murmur in mitral stenosis
In mitral stenosis, the blood passes with difficulty
from the left atrium into the left ventricle due to the
pressure difference.
It produce a murmur, which is very weak.

Special applications OF
PHONOCARDIOGRAM
A sthethoscopic microphone with
large chest piece is applied over that
part of the maternal solution where
auscultation reveals fetal heart
tones.
Simultaneously with the fetal sound
tracing, maternal ECG is recorded
for comparison.
Fetal
Phonocardiogram

Esophageal
Phonocardiogram
Basic interest in the method lies in the fact
that the heart sounds are collected from
the inside chest.
In general, sounds and murmur have lower
frequencies than when recorded by
conventional techniques.
The heart sounds are with shorter
duration.

Tracheal
Phonocardiogram
Tracheal Phonocardiogram have been
recorded in the patients by the means of a
tracheal cannula.
The technique consist of connecting the
outer end of the cannula with a
microphone be mean of the short piece of
rubber tube.
The heart sound are with shorter
duration and have vibration of a lower
frequency than recorded from outside
the chest.

UNIT II BIO-CHEMICAL AND NON
ELECTRICAL PARAMETER MEASUREMENT
pH, PO2, PCO2, colorimeter, Auto analyzer,
Blood flow meter, cardiac output, respiratory
measurement, Blood pressure, temperature,
pulse, Blood Cell Counters.

What are Acids?
• Acids are common
• Some are dangerous
and can burn your
skin
• Some are safe to eat
and drink
• Stomach acid helps
digest food
explosion

Acids
• Definition
– A group of compounds which behave similarly
– All have low pH
– Turn Litmus paper RED
– All donate H+ ions in aqueous solution
• Examples
– Hydrochloric HCl
– Sulfuric H2SO4
– Nitric HNO3
– Ethanoic CH3COOH

Acids
• A dilute acid has lots of water and a small
amount of acid
• A concentrated acid has lots of acid and not
much water so must be handled carefully
• A strong acid releases lots of H+
• A weak acid releases fewer H+

What are Bases (Alkalis)?
• In our home we
often use bases to
clean things. Eg
Bleach and
toothpaste
• Some things are not
acids or bases, we
say that they are
neutral. Eg Water

Bases
• Definition
– A family of compounds that behave similarly
– Have a high pH
– Turn litmus BLUE
– All donate OH-
• Examples
– Ammonia NH3
– Sodium Hydroxide NaOH

Measuring acid strength?
• To decide if something is an acid or a base we
can use an indicator.
• Litmus and Universal Indicator are examples
of indicators.
• They change colour depending on if they are
in an acid or a base.

Working with Indicators
• Red litmus turns BLUE in the presence of
Bases
• Blue litmus turns RED in the presence of
acid
• Acids and bases react together in a
NEUTRALISATION reaction

Acid Reactions
• Acid + Base  Salt + Water
• Acid + Metal  Salt + Hydrogen
• Acid + Carbonate  Salt + Water + Carbon Dioxide
– Hydrochloric acids (HCl) form CHLORIDE salts
– Nitric acid (HNO3) forms NITRATE salts
– Sulfuric acid (H2SO4) forms SULFATE salts

pCO2 (Partial Pressure of Carbon Dioxide)
• reflects the the amount of carbon dioxide gas
dissolved in the blood.
• Indirectly, the pCO2 reflects the exchange of this gas
through the lungs to the outside air. Two factors each
have a significant impact on the pCO2. The first is
how rapidly and deeply the individual is breathing:
• Someone who is hyperventilating will "blow off"
more CO2, leading to lower pCO2 levels
• Someone who is holding their breath will retain CO2,
leading to increased pCO2 levels

The second is the lungs capacity for freely exchanging
CO2 across the alveolar membrane:
• With pulmonary edema, there is an extra layer
of fluid in the alveoli that interferes with the
lungs' ability to get rid of CO2. This leads to a
rise in pCO2.
• With an acute asthmatic attack, even though
the alveoli are functioning normally, there
may be enough upper and middle airway
obstruction to block alveolar ventilation,
leading to CO2 retention.

Increased pCO2 is caused by:
• Pulmonary edema
• Obstructive lung disease

Decreased pCO2 is caused by:
• Hyperventilation
• Hypoxia
• Anxiety
• Pregnancy
• Pulmonary Embolism (This leads to hyperventilation, a more
important consideration than the embolized/infarcted areas
of the lung that do not function properly. In cases of massive
pulmonary embolism, the infarcted or non-functioning areas
of the lung assume greater significance and the pCO2 may
increase.)

PO2 (Partial Pressure of Oxygen)
• reflects the amount of oxygen gas dissolved in the blood. It primarily
measures the effectiveness of the lungs in pulling oxygen into the blood
stream from the atmosphere.
• Elevated pO2 levels are associated with:
• Increased oxygen levels in the inhaled air
• Polycythemia
• Decreased PO2 levels are associated with:
• Decreased oxygen levels in the inhaled air
• Anemia
• Heart decompensation
• Chronic obstructive pulmonary disease
• Restrictive pulmonary disease
• Hypoventilation

CO2 Content
• is a measurement of all the CO2 in the blood.
• Most of this is in the form of bicarbonate (HCO3),
controlled by the kidney. A small amount (5%) of the
CO2 is dissolved in the blood, and in the form of
soluble carbonic acid (H2CO3).
• For this reason, changes in CO2 content generally
reflect such metabolic issues as renal function and
unusual losses (diarrhea). Respiratory disease can
ultimately effect CO2 content, but only slightly and
only if prolonged.

• Elevated CO2 levels are seen in:
• Severe vomiting
• Use of mercurial diuretics
• COPD
• Aldosteronism
• Decreased CO2 levels are seen in:
• Renal failure or dysfunction
• Severe diarrhea
• Starvation
• Diabetic Acidosis
• Chlorthiazide diuretic use

OBJECTIVES
• Definition.
• Measurement of cardiac
output.
• Variations in cardiac output.
• Regulation of cardiac output.
• Heart lung preparation.
• Cardiac & vascular function
curves.
Monday, August 7, 2023

Some Facts………
 Is about 4.8 inches tall and 3.35 inches wide
 Weighs about .68 lb. in men and .56 lb. in women
 Beats about 100,000 times per day
 Beats 2.5 billion time in an average 70 yr. lifetime
 Pumps about 2000 gallons of blood each day
 Circulates blood completely 1000 times each day
 Pumps blood through 62,000 miles of vessels
 Suffers 7.2 mil. CAD deaths worldwide each year

DEFINITION.
• Amount of blood ejected
by each ventricle per
minute.
• CO = SV * HR…..
– SV – Stroke Volume.
– HR – Heart rate.
• Cardiac output
– 80 * 70 = 5.6 L/min.

SIGNIFICANCE
• It’s the cardiac output
that decides the rate of
blood flow to the
different parts of the
body.
• Decrease in cardiac
output
• Decrease in blood flow

RELATIONSHIP OF CARDIAC OUTPUT
& VENOUS RETURN
• VENOUS RETURN
• It is the quantity of blood
returned from all over
the body through the
veins into the right
atrium each minute
• Venous return = cardiac
output

Components…….
• Stroke volume
– Amount of blood pumped
by each ventricle per beat
or per contraction.
– 80 ml.
• Stroke volume depends
on –
– End diastolic volume
– contractility

Components…….
• Heart rate
– Under normal
circumstances 70
times/min.
– Increase in heart rate
increases Cardiac
output… but upto limit
– After it decreases due to
decrease in Cardiac
filling.

MINUTE VOLUME
It is the amount of
blood pumped out by
each ventricle per
minute.
MINUTE VOLUME = Stroke
volume x HR
Normal value:
5litres/ventricle/minute.

CARDIAC INDEX.
• Cardiac output
is the amount of blood pumped
out per ventricle per minute
per square meter of body
surface area.
• Expressed in relation to the
body surface area.
• Normal value – 3.2L/min/m2

CARDIAC RESERVE.
• Maximum increase in the
cardiac output above the
normal value.
• Expressed in Percentage.
• Normal values.
– Adults – 300-400%
– Old age – 200-250%
– Athletes – 500-600%
• Variations
– Maximum – Heavy
exercise.
– Minimum – Cardiac
diseases.

MEASUREMENT OF CARDIAC OUTPUT.
• Methods based on Fick’s
principle
• Indicator or dye dilution
method.
• Thermodilution
• Inhalation of inert gases.
• Physical methods
– Doppler echocardiography.
– Ballistocardiography.
– Cineradiographic technique.

METHODS BASED ON FICK’S PRINCIPLE
• Fick’s principle –
Amount of substance
taken up by an organ
per unit of time (Q) is
equal to the arterial
level of the substance
(A) – venous level of
substance (V) × Blood
flow(F)
• Q = (A-V) F
• F = Q
-------
(A-V)
• 2 methods
– Direct
– Indirect

METHODS BASED ON FICK’S
PRINCIPLE

DIRECT METHOD.
• Principle – pulmonary
blood flow = Rt ventricular
blood flow = Lt ventricular
blood flow.
• Pulmonary blood flow =
amount of O2 taken by
lungs
-------------------------------
PVO2-PAO2
• Amount of O2 taken
determined by
spirometer.
• PVO2 – from any
peripheral artery
• PAO2 – from pulmonary
artery.

DIRECT METHOD.
• Pulmonary blood flow =
amount of O2 taken by
lungs
-------------------------------
PVO2-PAO2
• CO = 2000/ (200-160) × 100
• CO = 5000ml/min
• Disadvantages.
– Invasive, risk of infection
& hemorrhage.
– Pt is conscious so CO is
more than normal
– Complications –
ventricular fibrillations.

DIRECT METHOD.

INDIRECT METHOD.
• Same as direct method
only
– CO2 excretion by lungs is
measured by spirometry.
– PACO2 from alveolar air.
– PVCO2 – Rebreathing
into closed bag.
• CO = CO2 output/min
----------------------
PACO2-PVCO2

INDICATOR OR DYE DILUTION METHOD.
• Principle – Known
amount of dye injected
into Rt atrium & mean
concentration of its first
passage through an
artery is determined.
• Blood flow (F)= Q/Ct
• F = blood flow in L/min.
• Q= quantity of dye
injected.
• C = Mean Conc. of dye.
• T = Time duration in sec
of first passage of dye.

IDEAL INDICATOR.
• Should be nontoxic.
• Mix evenly.
• Easy to measure.
• Not alter cardiac output
or haemodynamic.
• Not be changed by body.
• E.g. Evan’s blue,
radioactive isotopes.

PROCEDURE.
• 5 mg of Evan’s blue dye
mixed with venous blood.
• Duration of first passage of
dye(t) & mean conc of dye
(C) in arterial blood
estimated.
• CO= Q/ct × 60 = 5/1.5L ×40
× 60 = 5 L/min

THERMODILUTION
• PRINCIPLE – same as
indicator dye dilution
method except cold
saline is used.
• Resultant change in
blood temperature in
pulmonary artery is
determined.

INHALATION OF INERT GASES.
• NO, Acetylene – used.
• Pulmonary blood flow is
determined from
following values
– Quantity of gas absorbed
in given time.
– Partial pressure of gas in
alveolar air.
– The solubility of gas.

PHYSICAL METHODS
• Doppler
echocardiography –
– Ultrasonic evaluations of
cardiac functions.
– B-scan ultrasound at a
frequency of 2.25 MHz
using a transducer.
– Measure EDV, ESV,CO &
Valvular defects.

PHYSICAL METHODS
• Ballistocardiography
– Graphical record of the
pulsations created due
to ballistic recoil of the
pumping heart.

PHYSICAL METHODS
• CINERADIOGRAPHIC
TECHNIQUE.
• The making of a motion
picture record of successive
images appearing on a
fluoroscopic screen.
• Radiography of an organ in
motion, for example, the
heart, the gastrointestinal
tract.

Introduction
• This technique involves direct
measurement of arterial pressure
by inserting a catheter (thin,
hollow, and flexible tube).
• Invasive (intra-arterial) blood
pressure (IBP) monitoring is a
commonly used technique in the
Intensive Care Unit (ICU) and
in the operating theatre.

Cont. Introduction
• IBP technique also allows accurate blood
pressure readings specially the very low
pressures, for example in shocked patients.
• It allows continuous ‘beat-to-beat’ blood
pressure monitoring.
• Its complex procedure involves many risks.

The first invasive blood
pressure measurement
• The first invasive
attempt to measure
blood pressure was
made by Stephen
Hales in 1733.
• He inserted a glass
tube directly into the
artery of a horse

Advantages of direct arterial blood
• Arterial blood sampling
• Continuous real-time monitoring
• Intentional pharmacologic or mechanical
cardiovascular manipulation
• Failure of indirect blood pressure
measurement
• Supplementary diagnostic clues.

Implantation technique for blood
• A novel less-invasive blood pressure
monitoring system involve the principle:
if a blood vessel is pressed against a flat
surface of a pressure sensor diaphragm until
vessel flattening occurs, according to
Laplace’s law the pressure measured by the
sensor will be approximately equal to the
pressure inside the vessel

Implantable blood pressure
monitoring system

Prototype implantable blood pressure
monitoring
cuff with rigid isolation ring

UNIT III ASSIST DEVICES
Cardiac pacemakers, DC Defibrillator,
Dialyser, Ventilators, Magnetic Resonance
Imaging Systems, Ultrasonic Imaging
Systems.

146
History
• First pacemaker implanted in 1958
• First ICD implanted in 1980
• Greater than 500,000 patients in the US
population have pacemakers
• 115,000 implanted each year

147
Pacemakers Today
• Single or dual chamber
• Multiple programmable features
• Adaptive rate pacing
• Programmable lead configuration

148
Internal Cardiac Defibrillators (ICD)
• Transvenous leads
• Multiprogrammable
• Incorporate all capabilities of contemporary
pacemakers
• Storage capacity

149
Temporary Pacing Indications
• Routes = Transvenous, transcutaneous, esophageal
• Unstable bradydysrhythmias
• Atrioventricular heart block
• Unstable tachydysrhythmias
• *Endpoint reached after resolution of the problem or
permanent pacemaker implantation

150
Permanent Pacing Indications
• Chronic AVHB
• Chronic Bifascicular and Trifascicular Block
• AVHB after Acute MI
• Sinus Node Dysfunction
• Hypersensitive Carotid Sinus and Neurally Mediated
Syndromes
• Miscellaneous Pacing Indications

151
Chronic AVHB
• Especially if symptomatic
Pacemaker most commonly indicated for:
• Type 2 2º
– Block occurs within or below the Bundle of His
• 3º Heart Block
– No communication between atria and ventricles

152
Chronic Bifascicular and Trifascicular
Block
• Differentiation between uni, bi, and
trifascicular block
• Syncope common in patients with
bifascicular block
• Intermittent 3º heart block common

153
AVHB after Acute MI
• Incidence of high grade AVHB higher
• Indications for pacemaker related to
intraventricular conduction defects rather
than symptoms
• Prognosis related to extent of heart damage

154
Sinus Node Dysfunction
• Sinus bradycardia, sinus pause or arrest, or
sinoatrial block, chronotropic incompetence
• Often associated with paroxysmal SVTs
(bradycardia-tachycardia syndrome)
• May result from drug therapy
• Symptomatic?
• Often the primary indication for a pacemaker

155
Device Selection
• Temporary pacing (invasive vs. noninvasive)
• Permanent pacemaker
• ICD

156
Unipolar Pacemaker
Lead has only one electrode that contacts the
heart at its tip (+) pole
The power source is the (-) pole
Patient serves as the grounding source
Patient’s body fluids provide the return
pathway for the electrical signal
Electromagnetic interference occurs more often
in unipolar leads

158
Bipolar Pacemaker
If bipolar, there are two wires to the heart or
one wire with two electrodes at its tip
Provides a built-in ground lead
Circuit is completed within the heart
Provides more contact with the endocardium;
needs lower current to pace
Less chance for cautery interference

160
Indications
6. Complete heart block
7.Sinus arrest/block
8.Tachyarrhythmias
Supraventricular, ventricular
To overdrive the arrhythmia

161
Atrial Fibrillation
* A fibrillating atrium cannot be paced
* Place a VVI
* Patient has no atrial kick

162
Pacemaker Characteristics
• Adaptive-rate pacemakers
•Single-pass lead Systems
• Programmable lead configuration
• Automatic Mode-Switching
• Unipolar vs. Bipolar electrode configuration

163
Unipolar Pacemaker
Lead has only one electrode that contacts the
heart at its tip (+) pole
The power source is the (-) pole
Patient serves as the grounding source
Patient’s body fluids provide the return
pathway for the electrical signal
Electromagnetic interference occurs more often
in unipolar leads

164
Types
1. Asynchronous/Fixed Rate
2. Synchronous/Demand
3. Single/Dual Chamber
Sequential (A & V)
4. Programmable/nonprogrammable

165
Asynchronous/Fixed Rate
 Does not synchronize with intrinsic HR
 Used safely in pts with no intrinsic
ventricular activity
If pt has vent. activity, it may compete
with pt’s own conduction system
VT may result (R-on-T phenomenon)
EX: VOO, AOO, DOO

166
Synchronous/Demand
Contains two circuits
* One forms impulses
* One acts as a sensor
When activated by an R wave, sensing circuit
either triggers or inhibits the pacing circuit
Called “Triggered” or “Inhibited” pacers
Most frequently used pacer
Eliminates competition;
Energy sparing

Ventilator
• Ventilator is a machine which is designed to
mechanically move breathable air into and out
of the lungs, to provide the mechanism of
breathing for a patient who is physically
unable to breathe sufficiently.
• Ventilation is a method of controlling the
environment with the air.

• It is defined as the movement of air between
the environment and lungs via
inhalation(inspiration) and
exhalation(expiration).
• When artificial ventilation is required for a
long time, a ventilator is used to provide
oxygen enriched, medicated air to a patient at
a controlled temperature.

Working:
During inspiration
• First,air compressor draws room air through an air filter
and passes it to the main solenoid.
• Main solenoid forces the bottom inlet valve of the internal
bellows chamber to open and the lower outlet valve to
close.
• Oxygen is passed into bellows chamber in a controlled
manner by means of a control valve. The high pressure in
the bellows chamber compresses the bellows and forces
the upper outlet valve to open.
• Thus the compressed oxygen enriched air is passed through
the main solenoid into the external tubes and then the
bacterial filter, humidifier, nebulizer and finally to the
patient lungs.

• Humidifler is used to prevent damage to the patient's
lungs.
• Nebulizer is used to spray water or liquid medication
into the patient's inspired air in the form of aerosols.
• A sensitivity control monitors the negative pressure
necessary to initiate inspiration when the ventilator is
used in the assisted mode.
• When the medicated air is forced into lungs through
the valve number 1, the spirometer is in closed
condition. When the inspiration is complete, the main
solenoid switches the directions of the pneumatic air
to do the expiration cycle.

During expiration:
• First,air is sucked into the spirometer chamber through the valve
number 1. The volume of the chamber is varied by means of a light
weight piston that moves freely in a cylinder as air is withdrawn.
• Meanwhile the room air is drawn from the air inlet filter by the air
compressor and is directed to close the upper outlet valve of the
bellows located inside the unit. The weight of the bellows causes
the bottom bellows chamber outlet valve to open and the main
solenoid directs air to close the inlet valve of the internal bellows
chamber. The spirometer alarm indicates the correct volume of
exhaled air from the lungs. Through the outlet valve numbered as 2,
the expired air reaches the main solenoid.
• After the end of patient expiration, the system electronics trip the
main solenoid, thereby initiating the patient, inspiration part of the
cycle. Nowadays, microprocessor based control circuits are used in
the ventilator system to improve the system's reliability and
accuracy.

Modes of operation
• 1)Assist mode
• 2)Control mode
• 3) Assist and Control mode
• 1)Assist Mode:
• It is employed when the patient is able to control breath
but not able to inhale sufficient amount of air without
clinical assistance.
2) Control mode
• It is employed when the patient is not able to breath and a
timer is available to maintain the respiration rate.
3)Assist and Control mode
• In this mode, initially it will be in the assist mode and when
the patient fails to breath for a pre-determined period of
time then it will be in the control mode.

Types of Ventilators
• 1)Pressure limited Ventilator
• i)Positive Pressure
• ii)Negative Pressure
• 2)Volume limited Ventilator
• 3)Servo controlled Ventilator

1)Pressure limited Ventilator:
• It is based on the principle that the inspiration is
terminated when the gaseous mixture pumped
into the patient's lungs reachesa pre-set pressure.
• Pressure-limited ventilators are driven by the
compressed gaseous mixture used for ventilation.
• It is simple in design and reliable.
• i)Positive Pressure
• ii)Negative Pressure

2)Volume limited Ventilator:
• It works on the principle that for each breath a
constant volume of air is delivered.
• During inspiration, a constant volume of air is
sent to the lungs by applying pressure to a
chamber containing constant volume of air.
• It does not give the desired ventilation in
cases where the pre-set maximum pressure
cannot completely empty the chamber.

3)Servo controlled Ventilator:
• It works with the help of electronic control
circuit such that the flow of to and from the
patient is controlled by feedback circuits.
• It also monitors the pressure, compute
mechanical lung parameters and activates
alarm in the case of emergency attention by
doctors.

MAGNETIC RESONANCE
IMAGING
(MRI)

MRI
It is a technique which uses a
large magnet, radio waves and a
computer to create a detailed, cross
sectional image of internal organs
and structures.
It differs from other X-rays and
CT scans as it does not use
potentially harmful ionizing
radiation.
MRI Principle
??!

1)SCANNER
Main components in MRI
Scanner
Computers
Recording hardware
It is a large tube
that contains
powerful
magnets.
They consists of
3 main coils.
They are
Gradient coils
RF coils
Static magnetic
field coils.

ADVANTAGES:
No ionizing radiation.
Non invasive imaging
technique.
Better contrast
resolution.
Direct multiplaner
imaging.
3 Principal MRI
parameters:
Spin density
Spin
Lattice(Longitudinal)
relaxation time, T1
Spin-spin (or)
Transverse relaxation
time, T2

DIAGRAMS REPRESENTING PARAMETERS

DISADVANTAGES:
Very expensive.
Dangerous for patients with
metallic devices within the
body.
Movement during scanning
may cause blurry images.
RF transmitters can cause
severe burns if mishandled.

ULTRSONOGRAPHY Frequency range:
1 to 15 MHz..
Velocities in soft tissues and bones
are 1570 m/sec & 3600m/sec.
Diagnostic aids are based on
Echo aspect
Doppler shift aspect
THERAPEUTIC AIDS are
based on
Thermal effect
Non Thermal
(Cavitation effect)

BLOCK DIAGRAM OF ULTRASONIC IMAGING
SYSTEM

APPLICATIONS:
Among the various modern techniques for
the imaging of internal organs, ultrasonic
devices are by far the least expensive.
Ultrasound is also used for treating joint
pains and in the elimination of kidney and
bladder stones.
They are non-invasive.
Limitation:
One particular limitation is that it
requires the knowledge and expertise of a
well trained and skilled operator.

Limitations:
Bone injury, long injury
and intra luminal injury of
the GI tract cannot be
evaluated.
Ultra sound cannot
penetrate gas and bones
due to acoustic impedance
mismatch at soft tissue
bone (or) soft tissue –gas
interface.

UNIT IV PHYSICAL MEDICINE AND
BIOTELEMETRY
Diathermies- Shortwave, ultrasonic and
microwave type and their applications,
Surgical Diathermy, Biotelemetry.

What is Diathermy?
It comes from the Greek word
which means “through heating.”
It is a medical and surgical
technique involving the production of
heat in a part of the body by high-
frequency electric currents.
It stimulates the circulation, relieve
pain, destroy unhealthy tissue, or cause
bleeding vessels to clot.

Advantages of Diathermy:
1. Used in surgical procedures.
2. Normally it is a painless procedure.
3. It is used as a relief from various pains.
4. It is used as a method to prevent bleeding.
5. With diathermy procedures, the rate of blood
flow increase which results in fast recovery.
6. Diathermy helps in relaxation.

TYPES OF DIATHERMY
Shortwave
Microwave
Ultrasonic
Surgical

SHORT WAVE BLOCK DIAGRAM
Power Supply
RF Oscillator Monitor
control
Isolation
transformer
To Patient
Electrodes
The Frequency used can be
about 10-100MHz.
But the most commonly used is
27.12 MHz & wavelength is 11m

Shortwave Diathermy is of
2 types.
CAPACITIVE method
INDUCTIVE method
In Capacitive method the
electrode pads form a capacitor plates
and the body tissues between the pads
act as a dielectric, thus the whole
arrangement forms a capacitor.
When RF current is applied
to the electrodes then the capacitor
produces heat in the inter lying
tissues.

In Inductive method a flexible coil is
coiled around the arm or knee or any
other portion of the body which is to
be treated.
When the electrostatic field set up is
given between the ends of the cable
deep heating of the tissue occurs.
Thus the tissues get heated by the
eddy currents that are produced due to
the magnetic field around the cable.

INDUCTIVE
METHOD
(INDUCTOTHERMY)
USING OF CONTINUOUS
RF WAVES
(DIPULSE SHORT-WAVE
DIATHERMY)

Advantages and Applications
Here there is no danger of burns or
irritation and the patient has no discomfort.
Healing rate of tissue is increased.
Penetration of RF waves can be easily
adjusted.
It has been used to treat pain from kidney
stones, and pelvic inflammatory disease and
used for conditions that cause pain and muscle
spasms such as sprains, strains, bursitis,
tenosynovitis.

Microwave diathermy
The Frequency used can be about
300MHz-300GHz of 10mm-1m
But the most commonly used is
2450 MHz & wavelength is 12.25Cm
Generator main
components
A Coaxial cable
A director
A multi –cavity
magnetron valve

THERAPEUTIC EFFECTS:
Relief of pain.
Reduce muscle spasm.
Promote healing.
DOSAGE:
Care should be taken while the
treatment is made near the eyes.
There are possibilities of
overheating here.
If significant heating required 30
min would be reasonable.

ULTRASONIC DIATHERMY
1)It is used for curing
the diseases of
peripheral nervous
system, skeletal muscle
system and skin ulcers.
2)It is adopted when
the SWD fails and it
helps to achieve the
localisation of heat to
the affected part.
The Frequency used
can be about
800 KHz & wavelength
is 1MHz

SURGICAL DIATHERMY
Cutting
Coagulation
The Frequency
used can be about
1-3 MHz.

ADVANTAGES
Coagulation
method prevents
the contamination
of bacteria.
Bleeding can be
arrested
immediately by
touching the spot
with the
coagulation
electrode.
Provides simple
and effortless
surgery.

BLOCK DIAGRAM OF ELECTROSURGICAL
DIATHERMY
The Frequency
used can be about
250 KHz for
cutting.
Here, push-pull
amplifier is used.
So stepping up and
stepping down is
possible.

CLASS –B PUSH-PULL
AMPLIFIER

Biotelemetry:
• Measurement of biological parameters over a distance is
known as biotelemetry.
Applications:
• (1) Monitoring physiological conditions of astronauts in
space, workers in deep mines.
• (2) Monitoring physiological conditions of subjects during
exercise or in a normal working environment.
• (3) Monitoring physiological conditions of patients in an
ambulance or in a location away from the hospital.
• (4) Remote medical data collection from home or office.
• (5) Monitoring animals for research in their natural habitat.

UNIT V RECENT TRENDS IN MEDICAL
INSTRUMENTATION
Telemedicine, Insulin Pumps, Radio pill,
Endomicroscopy, Brain machine interface, Lab
on a chip.

Telemedicine using mobile satellite
communication
• Satellite Communication has been used to deliver
telemedicine services to areas that lack an
advanced terrestrial network. In fact, satellite link
is the best option to connect a remote site
without any or with an unreliable,
communication link, with high and flexible
bandwidth provision in shortest possible time,
though currently it is costly. The rapid
development in mobile and satellite
communication technology have opened up new
possibilities for mobile telemedicine in
emergency situations.

• The above figure shows a patient in a mobile station such
as an ambulance where color images, audio signals and
physiological signals such as ECG and blood pressure are
obtained using conventional sensors
transducers.
• These images and signals are multiplexed and transmitted
to a fixed station via a satellite communication network.
• In the fixed station, the signals received are demultiplexed
and presented to a medical specialist.
• Instructions from the specialist are then transmitted back
to the mobile station through the same satellite
communication link.

BENEFITS OF TELEMEDICINE
• Specialty healthcare accessible to under-served rural and
urban populations.
• Easy and quick access to specialists.
• Cut down cost of travelling and associated costs for
patients.
• Better organized and cost effective healthcare.
• Continuous education and training for rural healthcare
professionals.
• Very useful in follow up cases.
• Adds thousands of skilled specialists to the healthcare
team, immediately

Benefits of Telemedicine
• Improves access to rural and remote areas.
• Provides clinical support
• Overcomed the geographical barriers, connecting
users anywhere in the world.
• Improves quality of care.
• Early detection and treatment of disease.
• Improves patient documentation
• Reduces visits to special hospitals.
• Reduces cost due to transport.

TYPES OF TELEMEDICINE
• Store and Forward Telemedicine: The method by
which patient's medical data are acquired and
stored locally and later forwarded to expert
doctors at other centers.
• The remote centre receives the expert doctor’s
opinion within 48 hours or more. This is typically
used for nonemergency situations. Also, in this
case, the doctor's presence may not be required
at the time of data transfer.

• Real time Telemedicine: The method by which
patient's medical data is transmitted as it is
being acquired. One example is video
conferencing with attachment of medical
equipments like sonography machine,
endoscope etc. The video and medical data
transfer is done in real time and an expert
opinion can be sought instantly.

• Hybrid Telemedicine: Hybrid Telemedicine
covers features of Store and Forward as well
as Real Time Telemedicine.

Applications
• Telecardiology
• Teleradiology
• Telepathology
• Tele-surgery
• Teleeducation
• Teleconsultation

It is a peptide
hormone produced by
the beta cells of the
pancreatic islets.
It is considered to be
the main anabolic
hormone of the body .

TYPES OF
INSULIN
PUMPS:
Traditional
insulin pumps
Patch pumps
Insulin is
measured in
units where 1
units of insulin is
equivalent to ml.
Insulin is fed
into formats
based on the
dosage.
A Bolus dose
A Basal dose

PARTS OF
TRADITIONA
L PUMPS
Pump
Tubing
Infusion set
Angled sets
Straight sets

BLOCK DIAGRAM OF AN INSULIN
PUMP

INSULIN PENS AND SYRINGES ARE
AVAILABLE

CLASSIFICATION:
1)Bio
microelectromechanica
l systems(bioMEMS)
2)Mictrototal-analysis-
systems
LOC DEVICES:
1) Hand-held
2) Table-top LOC
systems
Liquid Flow:
1)Single Phase flow through
microchannels
2)Multiphase flow of droplets through
microchannels or on a surface.
Single phase:
Pressure driven LOC
Capillary driven LOC
Electrokinetic –driven
LOC
A Centrifugal driven
LOC

Re= (inertial
force)/(viscous
force)
PRESSURE-DRIVEN LOC

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