Sensors and. Transducers. D. Patranabis. Second Edition

Transcription

1 Sensors and Transducers Second Edition D. Patranabis

2 Sensors and Transducers Second Edition ion D. PATRANABIS Professor Department of Instrumentation and Electronics Engineering Jadavpur University Salt Lake Campus Kolkata Delhi

3 SENSORS AND TRANSDUCERS, Second Edition D. Patranabis 2003 by PHI Learning Private Limited, Delhi. All rights reserved. No part of this book may be reproduced in any form, by mimeograph or any other means, without permission in writing from the publisher. ISBN The export rights of this book are vested solely with the publisher. Twelfth Printing (Second Edition) January, 2013 Published by Asoke K. Ghosh, PHI Learning Private Limited, Rimjhim House, 111, Patparganj Industrial Estate, Delhi and Printed by Perfect Impression, New Delhi

4 Dedicated to My Parents

5 Contents Preface xi Chapter 1 GETTING STARTED! What are Sensors/Transducers? Principles Classification Parameters Characteristics 5 Static characteristics 5 Dynamic characteristics Environmental Parameters (EP) Characterization 10 Electrical characterization 10 Mechanical and thermal characterization 11 Optical characterization 13 Chemical/biological characterization 13 Review Questions 13 Chapter 2 MECHANICAL AND ELECTROMECHANICAL SENSORS Introduction Resistive Potentiometer Strain Gauge Resistance Strain Gauge Semiconductor Strain Gauges Inductive Sensors Sensitivity and Linearity of the Sensor Ferromagnetic Plunger Type Transducers Inductance with a Short-circuited Sleeve The Transformer Type Transducer Electromagnetic Transducer Magnetostrictive Transducer Materials Some Comments Capacitive Sensors The Parallel Plate Capacitive Sensor Serrated Plate Capacitive Sensor Variable Permittivity or Variable Thickness Dielectric Capacitive Sensor 51 v

6 vi Contents Stretched Diaphragm Variable Capacitance Transducer Electrostatic Transducer Piezoelectric Elements 55 Piezoelectric materials 56 Deformation modes and multimorphs The PZT Family Force/Stress Sensors Using Quartz Resonators Ultrasonic Sensors 64 Review Questions 65 Chapter 3 THERMAL SENSORS Introduction Gas Thermometric Sensors Thermal Expansion Type Thermometric Sensors Acoustic Temperature Sensor Dielectric Constant and Refractive Index Thermosensors Helium Low Temperature Thermometer Nuclear Thermometer Magnetic Thermometer Resistance Change Type Thermometric Sensors Metal Resistance Thermometric Sensors Thermistors Thermoemf Sensors Materials for Thermoemf Sensors E T Relations Thermocouple Construction Reference Temperature Thermosensors Using Semiconductor Devices Junction Semiconductor Types The PTAT Sensor Thermal Radiation Sensors Detectors Pyroelectric Thermal Sensors Quartz Crystal Thermoelectric Sensors NQR Thermometry Spectroscopic Thermometry Noise Thermometry Heat Flux Sensors 130 Review Questions 133 Chapter 4 MAGNETIC SENSORS Introduction Sensors and the Principles Behind The Yoke Coil Sensors The Coaxial Type Sensors Force and Displacement Sensors 146

7 Contents vii 4.3 Magnetoresistive Sensors Anisotropic Magnetoresistive Sensing Semiconductor Magnetoresistors 152 Effect of geometry 153 Effect of material Active Semiconductor Magnetic Sensors Hall Effect and Sensors The Hall Effect The Hall Effect Sensor 159 Sensor geometry and fabrication 160 Sensor performance Inductance and Eddy Current Sensors Variable Inductance Sensors The Plunger Type Sensors Variable Gap Sensors Linear Variable Differential Transformer (LVDT) Angular/Rotary Movement Transducers Synchros Synchro-resolvers Eddy Current Sensors Electromagnetic Flowmeter Switching Magnetic Sensors The Wiegand Sensor The Pulse Wire Sensor SQUID Sensors 180 Review Questions 181 Chapter 5 RADIATION SENSORS Introduction Basic Characteristics Types of Photosensistors/Photodetectors The Photoemissive Cell and the Photomultiplier The Photoconductive Cell 195 The LDR 195 Photocurrent 198 Noise Photovoltaic and Photojunction Cells 204 Reverse biased junction photocell Position-sensitive Cell Photoresistors and PhotoFETs and Other Devices X-ray and Nuclear Radiation Sensors The Ionization Chamber Proportional Counters Geiger Counters Scintillation Detectors 222

8 viii Contents Solid State Detectors Plastic Film and Luminescent Detectors Factors Affecting Radiation Measurement Fibre Optic Sensors Temperature Sensors Liquid Level Sensing Fluid Flow Sensing Microbend Sensors 230 Review Questions 231 Chapter 6 ELECTROANALYTICAL SENSORS Introduction The Electrochemical Cell The Cell Potential Standard Hydrogen Electrode (SHE) Liquid Junction and Other Potentials Polarization 239 Concentration polarization 239 Reaction polarization 240 Adsorption/desorption/crystallization polarization 240 Charge transfer polarization Reference Electrodes Sensor Electrodes Metal Electrodes Membrane Electrodes 244 The ion selective membrane electrodes 244 Molecular selective electrodes Temperature Sensing Electrodes Electroceramics in Gas Media Ionic Conductors 255 Zirconia 255 NASICON 257 b-alumina 257 Tin oxide 257 Zinc oxide 258 Titania (TiO 2 ) 258 Pervoskites 259 Varistors ChemFET 259 Review Questions 260 Chapter 7 SMART SENSORS Introduction Primary Sensors Excitation 267

9 Contents ix 7.4 Amplification Filters Converters Compensation Nonlinearity 269 Approximation and regression Noise and Interference Response Time Drift Cross-sensitivity Information Coding/Processing Data Communication Standards for Smart Sensor Interface The Automation 280 Review Questions 281 Chapter 8 RECENT TRENDS IN SENSOR TECHNOLOGIES Introduction Film Sensors Thick Film Sensors Thin Film Sensors Semiconductor IC Technology Standard Methods Microelectromechanical Systems (MEMS) Micromachining Some Application Examples Nano-sensors 296 Review Questions 298 Chapter 9 SENSORS THEIR APPLICATIONS Introduction On-board Automobile Sensors (Automotive Sensors) Flow-rate Sensors Pressure Sensors Temperature Sensors Oxygen Sensors Torque and Position Sensors Home Appliance Sensors Aerospace Sensors Static Pressure Sensors Temperature Sensing Fluid Velocity Sensors Sensing Direction of Air-flow Measuring Air-speed on Aircrafts Monitoring Strain, Force, Thrust, and Acceleration 314

10 x Contents 9.5 Sensors for Manufacturing Sensors 315 Distance sensing Medical Diagnostic Sensors Sensors 319 Radiation 319 Biomechanics 320 Temperature 320 Electromagnetic variable 320 Chemical and electrochemical sensors 320 Variables related to blood flow 321 Kinematic and geometric Sensors for Environmental Monitoring Pollution Hazards Sensing Environmental Pollution Ecological Studies of Air 323 Review Questions 324 Bibliography Index

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