Instrumentation Engineering : Analytical, optical & biomedical instrumentation, THE GATE ACADEMY

Analytical, Optical and
Biomedical Instrumentation
for
Instrumentation Engineering
By
www.thegateacademy.com

Syllabus A.O.B
THE GATE ACADEMY PVT.LTD. H.O.: #74, Keshava Krupa (third Floor), 30th
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
: 080-65700750,  info@thegateacademy.com © Copyright reserved. Web: www.thegateacademy.com
Syllabus for Analytical, Optical and Biomedical Instrumentation
Mass spectrometry. UV, visible and IR spectrometry. X-ray and nuclear radiation measurements.
Optical sources and detectors, LED, laser, Photo-diode, photo-resistor and their characteristics.
Interferometers, applications in metrology. Basics of fiber optics. Biomedical instruments, EEG,
ECG and EMG. Clinical measurements. Ultrasonic transducers and Ultrasonography. Principles of
Computer Assisted Tomography.
Analysis of GATE Papers
(Analytical, Optical and Biomedical Instrumentation)
Year Percentage of marks Overall Percentage
2013 3.0
12.12%
2012 6.0
2011 2.0
2010 9.0
2009 11.0
2008 16.0
2007 16.0
2006 14.66
2005 12.66
2004 25.0
2003 18.0

Contents A.O.B
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
C O N T E N T S
Chapter Page No.
#1. U.V, Visible and IR spectrometry 1 - 15
 Analytical Instrumentation 1 - 3
 Beer – Lamberts law 3 - 7
 Infrared Spectroscopy Instrumentation 7 - 9
 Assigment 1 10 - 11
 Assigment 2 11 - 12
 Answer Keys 13
 Explanations 13 - 15
#2. Mass Spectrometer 16 - 22
 Introduction 16 - 17
 Time of Flight Mass Spectrometer 17 - 18
 Assignment 19 - 20
 Answer Keys 21
#3. X ray and Nuclear Radiation Measurements 23 - 34
 Origin of X rays 23 - 24
 X-ray Diffraction – Bragg’s Law 24 - 26
 Nuclear Detectors 26 - 28
 Assignment 1 29 - 30
 Answer Keys 32
#4. Optical Sources and Detectors 35 - 55
 Optical Sources 35 - 37
 LASER 37 - 41
 Photo Detectors 41 - 49
 Answer Keys 53
#5. Interferometer, Applications in Metrology 56 – 63
 Introduction 56
 Michelson’s Interferometer Working 56 - 57
 Application in Metrology 57 - 58

Contents A.O.B
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
 Answer Keys 61
#6. Basics of Fiber Optics 64 – 76
 Introduction 64
 Construction 64 - 66
 Fibre Characteristics and Classification 66 - 69
 Answer Keys 73
#7. Ultrasonic Transducers and Ultrasonography 77 - 83
 Introduction 77
 Acoustic Impedence(z) 77
 Ultrasonic Transducers 78 - 79
 Doppler Shift Ultrasound Transducer 79
 Answer Keys 82
#8. ECG EEG EMG 84 - 102
 Sources of Bioelectric Potentials 84 - 87
 ECG (Electro Cardio Gram) 87 - 89
 EEG (Electro Encephalogram) 89 - 91
 EMG (Electromyogram) 91 - 94
 Answer Keys. 99
 Explanations. 99 - 102
#9. Clinical Measurement and
Computer Assisted Tomography 103 - 114
 Introduction 103
 Measurement of Blood Pressure 103 - 104
 Measurement of Blood Volume 104
 Measurement of Heart Sounds 105
 Test on Blood Cells 105 - 109
 Principle of Computer Assisted Tomography 109 - 110
 Answer Keys 113

Contents A.O.B
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
Module Test 115 - 126
 Test Questions 115 - 119
 Answer Keys 120
Reference Books 127

Chapter 1 A.O.B
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
: 080-65700750,  info@thegateacademy.com © Copyright reserved. Web: www.thegateacademy.com Page 1
CHAPTER 1
U.V, Visible and IR spectrometry
Analytical Instrumentation
 Analytical instruments are primarily used to obtained qualitative and quantitative
information regarding the composition of a given unknown sample.
 The basic building blocks are:
 Chemical information source generates signal containing information of the unknown
sample.
 Analytical instruments then generate signal based on the composition of the sample. This
stage forms an important building block in analytical instruments where the separation,
detection and of the composition is done by employing either emission or absorption or
scattering of electromagnetic radiation as the key principle of detection.
Electromagnetic Radiation
 Electromagnetic radiation is a type of energy that is transmitted through space at a speed of
3 × m/sec.
 These radiations do not require a medium of propagation and can also travel through
vacuum.
 Relation between the energy of electromagnetic radiation (normally called as photons) and
frequency of its propagation is given by
where E: energy
h: Planck’s constant ergs-s (or) Joules-s
ν: frequency
 If λ is the wavelength interval between successive maxima and minima of the wave), then
C = νλ
Where C: velocity of propagation of radiant energy in vacuum.
Interaction of radiation with matter
S. No Radiation absorbed Energy changes involved
1. Visible, ultraviolet, x –
ray
Electronic transitions, vibrational or
rotational changes
Chemical
information
source
Analytical
instrument
Signal
conditioner
Display
system

Chapter 1 A.O.B
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
2. Infrared Molecular vibrational changes with
superimpose rotational changes
3. Microwave Rotational changes
4. Radio – frequency They are absorbed by an intense magnetic
field.
Spectroscopic methods and corresponding energy states of matter or basis of phenomenon
S. No Method Phenomena employed
1. Nuclear magnetic
resonance
Nuclear spin coupling with an
applied magnetic field
2. Microwave spectroscopy Rotation of molecules
3. Infrared and Raman
spectroscopy
Rotation or vibration of molecules,
electronic transitions
4. UV – visible spectroscopy Electronic energy changes,
5. X-ray spectroscopy Diffraction and reflection of X-ray
radiation from atomic layers.
Electromagnetic Spectrum
Fig (1.1) shows the various regions of electromagnetic spectrum which are normally used in
spectroscopic works.
Fig.1.1 Electromagnetic spectrum from DC to X-ray
In the following sections, we discuss the various methods employed (by the analytical
instruments) for detection of the composition of the analyte sample in the different regions of
the electromagnetic spectrum.
λ 3× m 3× m
10 kHz 100 kHz 1 MHz 30 MHz 450 MHz 1 GHz 10 GHz 300 GHz 4.3× z z z z
MICROWAVES
VERY LOW
FREQUENCY
LOW
FREQUENCY
MEDIUM
FREQUENCY
HIGH
FREQUENCY
VERY HIGH
FREQUENCY
ULTRA HIGH
FREQUENCY
SUPER HIGH
FREQUENCY
EXTRA HIGH
FREQUENCY INFRARED VISIBLE ULTRAVIOLET X-RAY
FREQUENCY RANGE
OF HUMAN EYE
7000 – 4000 Å
300 m 10 m 0.67 m 30 m 3 cm m 7000 Å 3000 Å 30 Å 3×
MICROWAVE SPECTROSCOPY
2000 MHz – 300 GHz
20 – 100 MHz (~ 300 MHz IN
SUPERCONDUCTING INSTRUMENTS)
NUCLEAR MAGNETIC RESONANCE
UV – VISIBLE SPECTROSCOPY
2.5𝛍 M – 2400 Å
0 – 15 kHz; FREQUENCY RANGE
OF AVERAGE HUMAN EAR
NUCLEAR QUADRUPOLE
RESONANCE 2 – 1000 MHz ELECTRON SPIN
RESONANCE; X-BAND
9.46 GHz
INFRARED
SPECTROSCOPY 1 MM-
2.5 𝛍 M 10 – 4000 cm
RAMAN SPECTROSCOPY

Chapter 1 A.O.B
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
Visible and Ultraviolet: Calorimeter and Spectrophotometer
 In the visible and ultraviolet region of spectrum, the method of analysis employed by the
analytical instruments are based on the absorption of electromagnetic radiation.
 Calorimeters and spectrophotometers are the analytical instruments used in this region.
Principle
 Whenever a beam of radiant energy strikes the surface of a substance (analyte or sample),
the radiation interacts with the atoms or molecules of the substance resulting in absorption
(or) transmittance or scattering (reflection) depending on the properties of the sample.
 Absorption spectroscopy is based on the principle that the amount of absorption that occurs
is dependent on the number of molecules present in the sample.
 Here the analysis is done by studying the intensity of the radiant power leaving the
substance, i.e., the transmitted radiation which is an indication of concentration of the
sample.
 The absorbance is calculated as;
Transmittance (T)
where:
p: energy transmitted
P : Incident energy
Absorbance log ( ⁄ )
log ( )
Optical density log ( ⁄ )
Beer – Lamberts Law
 This law gives a relation between energy absorbed by the sample and the energy
transmitted.
Absorbance (A) = abc
where:
a is the absorptivity of the sample (constant)
Incident
Radiation
Absorbed
Radiation
Transmitted Radiation
Sample

Chapter 1 A.O.B
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
b is the thickness of the absorbing material
c is the concentration of the sample
As we known, A log ( ⁄ ) and T
p
P⁄
∴ log ( ⁄ ) abc log ( ) and T =
Assumptions
1. Here the radiation used is monochromatic (single wave length) in nature.
2. Sample is of low concentration.
3. The others factors that influence the absorption are not considered.
The instrument module for UV and visible spectrometry can be pictorized as below
Example: The transmittance of a coloured solution is 0.5, the absorption of the solution is?
A = log = log ) = 0.3
Example: In a particular sample the absorption is 0.6 for a molar concentration of the solute of
1.0 moles and 2cm path length the molar absorptivity is?
A = abc a =
Substitute a = 3000
Radiation sources used are
1. Hydrogen or deuterium discharge lamp(U.V)
2. Incandescent filament lamps 350nm – 2.5µm
3. Tungsten halogen lamps (visible)
Wavelength selection is done with the various dispersive techniques given.
Optical Filters
Absorption Filter
 These optical filters usually absorb the radiation and transmit light of single wavelength.
 There efficiency is poor, when compared to other filters.
Interference Filters
 These filters use interference phenomena.
Radiant
Source
Wavelength
Selector
Solvent Photo
detector
Read out
device
Sample

Chapter 1 A.O.B
Cross, 10th
Main, Jayanagar 4th
Block, Bangalore-11
 Thus, these filters normally have semi-transparent layers.
 Light, which is incident on it undergoes multiple reflections between the pair of semi
transparent layers and the wavelength that is transmitted through them is determined by
the thickness of the dielectric layer.
 The wavelength selection is done by the relation:
m λ d n) sin θ
where θ : angle of incidence
d : thickness of dielectric spaces,
n : refractive index of dielectric spacer.
m : order of interference
λ : wavelength
Monochromators
 They are the another class of filters, which provide better isolation than optical filters.
 They are capable or isolating a narrow band of wavelengths effectively.
 Principle employed for separation of wavelength is done by using a dispersing medium,
where the radiant energy gets isolated.
 Dispersion of radiant energy into different wavelength’s is usually done by prism
monochromators or by diffraction grating.
Prism Monochromators
 Here in prism monochromators, the isolation of different wavelengths is done by using the
refractive index of wavelengths, which is different for different wavelengths.
 Thus, radiation of different wavelengths gets disperssed at different angles by prism.
 Prisms are normally made of glass or quartz. Glass is used in visible region and quartz for
ultraviolet region.
Resolving Power (R)
The term resolving power is applied to spectrum producing devices and means as the ability of
the instrument to form separate images of two closely adjacent spectral lines.
 It is defined generally by the equation
where R: resolving power
λ : wavelength
dλ : smallest wavelength separation, which is separable with the instrument.
 dλ λ λ and .
For prism, the resolving power is given by the expression:
t
where dμ is the difference or refractive index
t : base of the prism.
Example: A prism spectrometer uses flint glam prism with glam dispersion 952cm-1 and dλ =
6 0A at λ = 5893 0A find base t of prism?

Instrumentation Engineering : Analytical, optical & biomedical instrumentation, THE GATE ACADEMY

Instrumentation Engineering : Analytical, optical & biomedical instrumentation, THE GATE ACADEMY

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Instrumentation Engineering : Analytical, optical & biomedical instrumentation, THE GATE ACADEMY