Handbook of Modern Sensors

Transcription

1 Handbook of Modern Sensors

2

3 Jacob Fraden Handbook of Modern Sensors Physics, Designs, and Applications Fifth Edition

4 Jacob Fraden Fraden Corp. San Diego, CA, USA ISBN ISBN (ebook) DOI / Library of Congress Control Number: Springer Cham Heidelberg New York Dordrecht London # Springer International Publishing Switzerland 2004, 2010, 2016 # American Institute of Physics 1993, 1997 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. The publisher, the authors and the editors are safe to assume that the advice and information in this book are believed to be true and accurate at the date of publication. Neither the publisher nor the authors or the editors give a warranty, express or implied, with respect to the material contained herein or for any errors or omissions that may have been made. Printed on acid-free paper Springer International Publishing AG Switzerland is part of Springer Science+Business Media (

5 Preface Numerous computerized appliances wash clothes, prepare coffee, play music, guard homes, and perform endless useful functions. However, no electronic device operates without receiving external information. Even if such information comes from another electronic device, somewhere in the chain, there is at least one component that perceives external input signals. This component is a sensor. Modern signal processors are the devices that manipulate binary codes generally represented by electric impulses. As we live in an analog world that mostly is not digital or electrical (apart from the atomic level), sensors are the interface devices between various physical values and the electronic circuits that understand only the language of moving electrical charges. In other words, sensors are eyes, ears, and noses of the silicon chips. This book is about the man-made sensors that are very much different from the sensing organs of living organisms. Since the publication of the previous edition of this book, sensing technologies have made remarkable leaps. Sensitivities of sensors have become higher, their dimensions smaller, selectivity better, and prices lower. A new, major field of application for sensors mobile communication devices has been rapidly evolving. Even though such devices employ sensors that operate on the same fundamental principles as other sensors, their use in mobile devices demands specific requirements. Among these are miniature dimensions and complete integration with the signal processing and communication components. Hence, in this new edition, we address in greater detail the mobile trend in sensing technologies. A sensor converts input signals of a physical nature into electrical output. Thus, we will examine in detail the principles of such conversions and other relevant laws of physics. Arguably one of the greatest geniuses who ever lived, Leonardo da Vinci, had his own peculiar way of praying (according to a book I read many years ago, by Akim Volinsky, published in Russian in 1900). Loosely, it may be translated into modern English as something like, Oh Lord, thank you for following Thy own laws. It is comforting indeed that the laws of Nature do not change it is our appreciation of the laws that is continually refined. The sections of the book that cover these laws have not changed much since the previous editions. Yet, the sections that describe the practical designs have been revised substantially. Recent ideas and developments have been added, while obsolete and less interesting designs were dropped. v

6 vi Preface In the course of my engineering work, I often wished for a book which combined practical information on the many subjects relating to the most important physical principles, design, and use of various sensors. Of course, I could browse the Internet or library bookshelves in search of texts on physics, chemistry, electronics, technical, and scientific magazines, but the information is scattered over many publications and websites, and almost every question I was pondering required substantial research. Little by little, I gathered practical information on everything which is in any way related to various sensors and their applications to scientific and engineering measurements. I also spent endless hours at a lab bench, inventing and developing numerous devices with various sensors. Soon, I realized that the information I had collected would be quite useful to more than one plerson. This idea prompted me to write this book, and this fifth updated edition is the proof that I was not mistaken. The topics included in the book reflect the author s own preferences and interpretations. Some may find a description of a particular sensor either too detailed or broad or perhaps too brief. In setting my criteria for selecting various sensors for this new edition, I attempted to keep the scope of this book as broad as possible, opting for many different designs described briefly (without being trivial, I hope), rather than fewer treated in greater depth. This volume attempts (immodestly perhaps) to cover a very broad range of sensors and detectors. Many of them are well known, but describing them is still useful for students and for those seeking a convenient reference. By no means this book is a replacement for specialized texts. It gives a bird s-eye view at a multitude of designs and possibilities, but does not dive in depth into any particular topic. In most cases, I have tried to strike a balance between details and simplicity of coverage; however simplicity and clarity were the most important requirements I set for myself. My true goal was not to pile up a collection of information but rather to entice the reader into a creative mindset. As Plutarch said nearly two millennia ago, The mind is not a vessel to be filled but a fire to be kindled... Even though this book is for scientists and engineers, as a rule, the technical descriptions and mathematic treatments generally do not require a background beyond a high school curriculum. This is a reference text which could be used by students, researchers interested in modern instrumentation (applied physicists and engineers), sensor designers, application engineers, and technicians whose job is to understand, select, or design sensors for practical systems. The previous editions of this book have been used quite extensively as desktop references and textbooks for the related college courses. Comments and suggestions from sensor designers, application engineers, professors, and students have prompted me to implement several changes and to correct errors. I am deeply grateful to those who helped me to make further improvements in this new edition. I owe a debt of gratitude and many thanks to Drs. Ephraim Suhir and David Pintsov for assisting me in mathematical treatment of transfer functions and to Dr. Sanjay V. Patel for his further contributions to the chapter on chemical sensors. San Diego, CA, USA April 12, 2015 Jacob Fraden

7 Contents 1 Data Acquisition Sensors, Signals, and Systems Sensor Classification Units of Measurements References Transfer Functions Mathematical Models Concept Functional Approximations Linear Regression Polynomial Approximations Sensitivity Linear Piecewise Approximation Spline Interpolation Multidimensional Transfer Functions Calibration Computation of Parameters Computation of a Stimulus Use of Analytical Equation Use of Linear Piecewise Approximation Iterative Computation of Stimulus (Newton Method) References Sensor Characteristics Sensors for Mobile Communication Devices Requirements to MCD Sensors Integration Span (Full-Scale Input) Full-Scale Output Accuracy Calibration Error Hysteresis Nonlinearity vii

8 viii Contents 3.8 Saturation Repeatability Dead Band Resolution Special Properties Output Impedance Output Format Excitation Dynamic Characteristics Dynamic Models of Sensor Elements Mechanical Elements Thermal Elements Electrical Elements Analogies Environmental Factors Reliability MTTF Extreme Testing Accelerated Life Testing Application Characteristics Uncertainty References Physical Principles of Sensing Electric Charges, Fields, and Potentials Capacitance Capacitor Dielectric Constant Magnetism Faraday Law Permanent Magnets Coil and Solenoid Induction Lenz Law Eddy Currents Resistance Specific Resistivity Temperature Sensitivity of a Resistor Strain Sensitivity of a Resistor Moisture Sensitivity of a Resistor Piezoelectric Effect Ceramic Piezoelectric Materials Polymer Piezoelectric Films Pyroelectric Effect Hall Effect

9 Contents ix 4.9 Thermoelectric Effects Seebeck Effect Peltier Effect Sound Waves Temperature and Thermal Properties of Materials Temperature Scales Thermal Expansion Heat Capacity Heat Transfer Thermal Conduction Thermal Convection Thermal Radiation References Optical Components of Sensors Light Energy of Light Quanta Light Polarization Light Scattering Geometrical Optics Radiometry Photometry Windows Mirrors Coated Mirrors Prismatic Mirrors Lenses Curved Surface Lenses Fresnel Lenses Flat Nanolenses Fiber Optics and Waveguides Optical Efficiency Lensing Effect Concentrators Coatings for Thermal Absorption Antireflective Coating (ARC) References Interface Electronic Circuits Signal Conditioners Input Characteristics Amplifiers Operational Amplifiers Voltage Follower

10 x Contents Charge- and Current-to-Voltage Converters Light-to-Voltage Converters Capacitance-to-Voltage Converters Closed-Loop Capacitance-to-Voltage Converters Sensor Connections Ratiometric Circuits Differential Circuits Wheatstone Bridge Null-Balanced Bridge Bridge Amplifiers Excitation Circuits Current Generators Voltage Generators Voltage References Oscillators Analog-to-Digital Converters Basic Concepts V/F Converters PWM Converters R/F Converters Successive-Approximation Converter Resolution Extension ADC Interface Integrated Interfaces Voltage Processor Inductance Processor Data Transmission Two-Wire Transmission Four-Wire Transmission Noise in Sensors and Circuits Inherent Noise Transmitted Noise Electric Shielding Bypass Capacitors Magnetic Shielding Mechanical Noise Ground Planes Ground Loops and Ground Isolation Seebeck Noise Batteries for Low-Power Sensors Primary Cells Secondary Cells Supercapacitors

11 Contents xi 6.9 Energy Harvesting Light Energy Harvesting Far-Field Energy Harvesting Near-Field Energy Harvesting References Detectors of Humans Ultrasonic Detectors Microwave Motion Detectors Micropower Impulse Radars Ground Penetrating Radars Linear Optical Sensors (PSD) Capacitive Occupancy Detectors Triboelectric Detectors Optoelectronic Motion Detectors Sensor Structures Multiple Detecting Elements Complex Sensor Shape Image Distortion Facet Focusing Elements Visible and Near-IR Light Motion Detectors Mid- and Far-IR Detectors Passive Infrared (PIR) Motion Detectors PIR Detector Efficiency Analysis Optical Presence Sensors Photoelectric Beam Light Reflection Detectors Pressure-Gradient Sensors D Pointing Devices Gesture Sensing (3-D Pointing) Inertial and Gyroscopic Mice Optical Gesture Sensors Near-Field Gesture Sensors Tactile Sensors Switch Sensors Piezoelectric Tactile Sensors Piezoresistive Tactile Sensors Tactile MEMS Sensors Capacitive Touch Sensors Optical Touch Sensors Optical Fingerprint Sensors References

12 xii Contents 8 Presence, Displacement, and Level Potentiometric Sensors Piezoresistive Sensors Capacitive Sensors Inductive and Magnetic Sensors LVDT and RVDT Transverse Inductive Sensor Eddy Current Probes Pavement Loops Metal Detectors Hall-Effect Sensors Magnetoresistive Sensors Magnetostrictive Detector Optical Sensors Optical Bridge Proximity Detector with Polarized Light Prismatic and Reflective Sensors Fabry-Perot Sensors Fiber Bragg Grating Sensors Grating Photomodulators Thickness and Level Sensors Ablation Sensors Film Sensors Cryogenic Liquid Level Sensors References Velocity and Acceleration Stationary Velocity Sensors Linear Velocity Rotary Velocity Sensors (Tachometers) Inertial Rotary Sensors Rotor Gyroscope Vibrating Gyroscopes Optical (Laser) Gyroscopes Inertial Linear Sensors (Accelerometers) Transfer Function and Characteristics Inclinometers Seismic Sensors Capacitive Accelerometers Piezoresistive Accelerometers Piezoelectric Accelerometers Thermal Accelerometers Closed-Loop Accelerometers References

13 Contents xiii 10 Force and Strain Basic Considerations Strain Gauges Pressure-Sensitive Films Piezoelectric Force Sensors Piezoelectric Cables Optical Force Sensors References Pressure Sensors Concept of Pressure Units of Pressure Mercury Pressure Sensor Bellows, Membranes, and Thin Plates Piezoresistive Sensors Capacitive Sensors VRP Sensors Optoelectronic Pressure Sensors Indirect Pressure Sensor Vacuum Sensors Pirani Gauge Ionization Gauges Gas Drag Gauge References Flow Sensors Basics of Flow Dynamics Pressure Gradient Technique Thermal Transport Sensors Hot-Wire Anemometers Three-Part Thermoanemometer Two-Part Thermoanemometer Microflow Thermal Transport Sensors Ultrasonic Sensors Electromagnetic Sensors Breeze Sensor Coriolis Mass Flow Sensors Drag Force Flowmeter Cantilever MEMS Sensors Dust and Smoke Detectors Ionization Detector Optical Detector References

14 xiv Contents 13 Microphones Microphone Characteristics Output Impedance Balanced Output Sensitivity Frequency Response Intrinsic Noise Directionality Proximity Effect Resistive Microphones Condenser Microphones Electret Microphones Optical Microphones Piezoelectric Microphones Low-Frequency Range Ultrasonic Range Dynamic Microphones References Humidity and Moisture Sensors Concept of Humidity Sensor Concepts Capacitive Humidity Sensors Resistive Humidity Sensors Thermal Conductivity Sensor Optical Hygrometers Chilled Mirror Light RH Sensors Oscillating Hygrometer Soil Moisture References Light Detectors Introduction Principle of Quantum Detectors Photodiode Phototransistor Photoresistor Cooled Detectors Imaging Sensors for Visible Range CCD Sensor CMOS Imaging Sensors UV Detectors Materials and Designs Avalanche UV Detectors

15 Contents xv 15.8 Thermal Radiation Detectors General Considerations Golay Cells Thermopiles Pyroelectric Sensors Microbolometers References Detectors of Ionizing Radiation Scintillating Detectors Ionization Detectors Ionization Chambers Proportional Chambers Geiger Müller (GM) Counters Semiconductor Detectors Cloud and Bubble Chambers References Temperature Sensors Coupling with Object Static Heat Exchange Dynamic Heat Exchange Sensor Structure Signal Processing of Sensor Response Temperature References Resistance Temperature Detectors (RTD) Ceramic Thermistors Simple Model Fraden Model Steinhart and Hart Model Self-Heating Effect in NTC Thermistors Ceramic PTC Thermistors Fabrication Silicon and Germanium Thermistors Semiconductor pn-junction Sensors Silicon PTC Temperature Sensors Thermoelectric Sensors Thermoelectric Laws Thermocouple Circuits Thermocouple Assemblies Optical Temperature Sensors Fluoroptic Sensors Interferometric Sensors Super-High Resolution Sensing Thermochromic Sensors Fiber-Optic Temperature Sensors (FBG)

16 xvi Contents Acoustic Temperature Sensors Piezoelectric Temperature Sensors References Chemical and Biological Sensors Overview Chemical Sensors Biochemical Sensors History Chemical Sensor Characteristics Selectivity Sensitivity Electrical and Electrochemical Sensors Electrode Systems Potentiometric Sensors Conductometric Sensors Metal Oxide Semiconductor (MOS) Chemical Sensors Elastomer Chemiresistors Chemicapacitive Sensors ChemFET Photoionization Detectors Physical Transducers Acoustic Wave Devices Microcantilevers Spectrometers Ion Mobility Spectrometry Quadrupole Mass Spectrometer Thermal Sensors Concept Pellister Catalytic Sensors Optical Transducers Infrared Detection Fiber-Optic Transducers Ratiometric Selectivity (Pulse Oximeter) Color Change Sensors Multi-sensor Arrays General Considerations Electronic Noses and Tongues Specific Difficulties References Materials and Technologies Materials Silicon as Sensing Material Plastics

17 Contents xvii Metals Ceramics Structural Glasses Optical Glasses Nano-materials Surface Processing Spin Casting Vacuum Deposition Sputtering Chemical Vapor Deposition (CVD) Electroplating MEMS Technologies Photolithography Silicon Micromachining Micromachining of Bridges and Cantilevers Lift-Off Wafer Bonding LIGA References Appendix Index

18

19 About the Author Jacob Fraden holds a Ph.D. in medical electronics and is President of Fraden Corp., a technology company that develops sensors for consumer, medical, and industrial applications. He has authored nearly 60 patents in the areas of sensing, medical instrumentation, security, energy management, and others. xix