Sensors, Actuators, and Their Interfaces: A multidisciplinary introduction

Description

Sensors and actuators are used daily in countless applications to ensure more accurate and reliable workflows and safer environments. Many students and young engineers with engineering and science backgrounds often come prepared with circuits and programming skills but have little knowledge of sensors and sensing strategies and their interfacing. In this fully revised and expanded second edition, the author looks at sensors and actuators based on a broad area of detection methods. He takes a general and applications-oriented approach to the topic and makes it discipline-independent to cater for a broad audience. Important coverage is given to interfacing (the processes and mechanisms between the sensors and actuators) that makes systems work reliably and accurately. Topics covered include different type of sensors and actuators (temperature, thermal, optical, electric, magnetic, mechanical, acoustic, chemical, radiation, and smart sensors) and their interfaces. The book contains numerous examples and problem sets as well as useful appendices. Other keywords: biological actuators; magnetic sensors; temperature sensors; radiation actuators; mechanical actuators; smart sensors; interfacing circuits; magnetic actuators; acoustic sensors; radiation sensors; MEMS actuators; smart actuators; electric sensors; acoustic actuators; chemical actuators; electric actuators; microprocessors; mechanical sensors; biological sensors; chemical sensors; thermal actuators; optical sensors; MEMS sensors Cover Contents Preface with publisher's acknowledgments Challenges Multidisciplinary approach Organization Limitations Resources Conclusion Publisher's acknowledgments About the author 1 Introduction 1.1 Introduction 1.2 A short historical note 1.3 Definitions 1.4 Classification of sensors and actuators 1.5 General requirements for interfacing 1.6 Units 1.6.1 Base SI units 1.6.2 Derived units 1.6.3 Supplementary units 1.6.4 Customary units 1.6.5 Prefixes 1.6.6 Other units and measures 1.6.6.1 Units of information 1.6.6.2 The decibel (dB) and its use 1.6.7 Convention for use of units 1.7 Problems Reference 2 Performance characteristics of sensors and actuators 2.1 Introduction 2.2 Input and output characteristics 2.2.1 Transfer function 2.2.2 Impedance and impedance matching 2.2.3 Range, span, input and output full scale, resolution, and dynamic range 2.2.4 Accuracy, errors, and repeatability 2.2.5 Sensitivity and sensitivity analysis 2.2.6 Hysteresis, nonlinearity, and saturation 2.2.7 Frequency response, response time, and bandwidth 2.2.8 Calibration 2.2.9 Excitation 2.2.10 Deadband 2.2.11 Reliability 2.3 Simulation 2.4 Problems 3 Temperature sensors and thermal actuators 3.1 Introduction 3.1.1 Units of temperature, thermal conductivity, heat, and heat capacity 3.2 Thermoresistive sensors 3.2.1 Resistance temperature detectors 3.2.1.1 Self-heat of RTDs 3.2.1.2 Response time 3.2.2 Silicon resistive sensors 3.2.3 Thermistors 3.3 Thermoelectric sensors 3.3.1 Practical considerations 3.3.2 Semiconductor thermocouples 3.3.3 Thermopiles and thermoelectric generators 3.4 p-n junction temperature sensors 3.5 Other temperature sensors 3.5.1 Optical and acoustical sensors 3.5.2 Thermomechanical sensors and actuators 3.6 Problems 4 Optical sensors and actuators 4.1 Introduction 4.2 Optical units 4.3 Materials 4.4 Effects of optical radiation 4.4.1 Thermal effects 4.4.2 Quantum effects 4.4.2.1 The photoelectric effect 4.4.2.2 Quantum effects: the photoconducting effect 4.4.2.3 Spectral sensitivity 4.4.2.4 Tunneling effect 4.5 Quantum-based optical sensors 4.5.1 Photoconducting sensors 4.5.2 Photodiodes 4.5.3 Photovoltaic diodes 4.5.4 Phototransistors 4.6 Photoelectric sensors 4.6.1 The photoelectric sensor 4.6.2 Photomultipliers 4.7 Charge coupled (CCD) sensors and detectors 4.8 Thermal-based optical sensors 4.8.1 Passive IR sensors 4.8.1.1 Thermopile PIR 4.8.1.2 Pyroelectric sensors 4.8.1.3 Bolometers 4.9 Active far infrared (AFIR) sensors 4.10 Optical actuators 4.11 Problems 5 Electric and magnetic sensors and actuators 5.1 Introduction 5.2 Units 5.3 The electric field: capacitive sensors and actuators 5.3.1 Capacitive position, proximity, and displacement sensors 5.3.2 Capacitive fluid level sensors 5.3.3 Capacitive actuators 5.4 Magnetic fields: sensors and actuators 5.4.1 Inductive sensors 5.4.1.1 Inductive proximity sensors 5.4.1.2 Eddy current proximity sensors 5.4.1.3 Position and displacement sensing: variable inductance sensors 5.4.2 Hall effect sensors 5.5 Magnetohydrodynamic (MHD) sensors and actuators 5.5.1 MHD generator or sensor 5.5.2 MHD pump or actuator 5.6 Magnetoresistance and magnetoresistive sensors 5.7 Magnetostrictive sensors and actuators 5.7.1 Magnetostrictive actuators 5.8 Magnetometers 5.8.1 Coil magnetometer 5.8.2 The fluxgate magnetometer 5.8.3 The SQUID 5.9 Magnetic actuators 5.9.1 Voice coil actuators 5.9.2 Motors as actuators 5.9.2.1 Operation principles 5.9.2.2 Brushless, electronically commutated DC (BLDC) motors 5.9.2.3 AC motors 5.9.2.4 Stepper motors 5.9.2.5 Linear motors 5.9.2.6 Servomotors 5.9.3 Magnetic solenoid actuators and magnetic valves 5.10 Voltage and current sensors 5.10.1 Voltage sensing 5.10.2 Current sensing 5.10.3 Resistance sensors 5.11 Problems 6 Mechanical sensors and actuators 6.1 Introduction 6.2 Some definitions and units 6.3 Force sensors 6.3.1 Strain gauges 6.3.2 Semiconductor strain gauges 6.3.2.1 Application 6.3.2.2 Errors 6.3.3 Other strain gauges 6.3.4 Force and tactile sensors 6.4 Accelerometers 6.4.1 Capacitive accelerometers 6.4.2 Strain gauge accelerometers 6.4.3 Magnetic accelerometers 6.4.4 Other accelerometers 6.5 Pressure sensors 6.5.1 Mechanical pressure sensors 6.5.2 Piezoresistive pressure sensors 6.5.3 Capacitive pressure sensors 6.5.4 Magnetic pressure sensors 6.6 Velocity sensing 6.7 Inertial sensors: gyroscopes 6.7.1 Mechanical or rotor gyroscopes 6.7.2 Optical gyroscopes 6.8 Problems 7 Acoustic sensors and actuators 7.1 Introduction 7.2 Units and definitions 7.3 Elastic waves and their properties 7.3.1 Longitudinal waves 7.3.2 Shear waves 7.3.3 Surface waves 7.3.4 Lamb waves 7.4 Microphones 7.4.1 The carbon microphone 7.4.2 The magnetic microphone 7.4.3 The ribbon microphone 7.4.4 Capacitive microphones 7.5 The piezoelectric effect 7.5.1 Electrostriction 7.5.2 Piezoelectric sensors 7.6 Acoustic actuators 7.6.1 Loudspeakers 7.6.2 Headphones and buzzers 7.6.2.1 The magnetic buzzer 7.6.2.2 The piezoelectric headphone and piezoelectric buzzer 7.7 Ultrasonic sensors and actuators: transducers 7.7.1 Pulse-echo operation 7.7.2 Magnetostrictive transducers 7.8 Piezoelectric actuators 7.9 Piezoelectric resonators and saw devices 7.10 Problems 8 Chemical and biological sensors and actuators 8.1 Introduction—chemistry and biochemistry 8.2 Chemical units 8.3 Electrochemical sensors 8.3.1 Metal oxide sensors 8.3.2 Solid electrolyte sensors 8.3.3 The metal oxide semiconductor chemical sensor 8.4 Potentiometric sensors 8.4.1 Glass membrane sensors 8.4.2 Soluble inorganic salt membrane sensors 8.4.3 Polymer-immobilized ionophore membranes 8.4.4 Gel-immobilized enzyme membranes 8.4.5 The ion-sensitive field-effect transistor 8.5 Thermochemical sensors 8.5.1 Thermistor-based chemical sensors 8.5.2 Catalytic sensors 8.5.3 Thermal conductivity sensors 8.6 Optical chemical sensors 8.7 Mass sensors 8.7.1 Mass humidity and gas sensors 8.7.2 SAW mass sensors 8.8 Humidity and moisture sensors 8.8.1 Capacitive moisture sensors 8.8.2 Resistive humidity sensor 8.8.3 Thermal conduction moisture sensors 8.8.4 Optical humidity sensor 8.9 Chemical actuation 8.9.1 The catalytic converter 8.9.2 The airbag 8.9.3 Electroplating 8.9.4 Cathodic protection 8.10 Problems 9 Radiation sensors and actuators 9.1 Introduction 9.2 Units of radiation 9.3 Radiation sensors 9.3.1 Ionization sensors (detectors) 9.3.1.1 Ionization chambers 9.3.1.2 Proportional chamber 9.3.1.3 Geiger–Muller counters 9.3.2 Scintillation sensors 9.3.3 Semiconductor radiation detectors 9.3.3.1 Bulk semiconductor radiation sensor 9.3.3.2 Semiconducting junction radiation sensors 9.4 Microwave radiation 9.4.1 Microwave sensors 9.4.1.1 Radar 9.4.1.2 Reflection and transmission sensors 9.4.1.3 Resonant microwave sensors 9.4.1.4 Propagation effects and sensing 9.5 Antennas as sensors and actuators 9.5.1 General relations 9.5.2 Antennas as sensing elements 9.5.2.1 Triangulation, multilateration, and the global positioning system 9.5.3 Antennas as actuators 9.6 Problems 10 MEMS and smart sensors and actuators 10.1 Introduction 10.2 Production of MEMS 10.3 MEMS sensors and actuators 10.3.1 MEMS sensors 10.3.1.1 Pressure sensors 10.3.1.2 Mass air flow sensors 10.3.1.3 Inertial sensors 10.3.1.4 Angular rate sensors 10.3.2 MEMS actuators 10.3.2.1 Thermal and piezoelectric actuation 10.3.2.2 Electrostatic actuation 10.3.3 Some applications 10.3.3.1 Optical switches 10.3.3.2 Mirrors and mirror arrays 10.3.3.3 Pumps 10.3.3.4 Valves 10.3.3.5 Other MEMS devices 10.4 Nanosensors and actuators 10.5 Smart sensors and actuators 10.5.1 Wireless sensors and actuators and issues associated with their use 10.5.1.1 The ISM and SRD bands 10.5.1.2 The wireless link and data handling 10.5.1.3 Transmitters, receivers, and transceivers 10.5.2 Modulation and demodulation 10.5.2.1 Amplitude modulation 10.5.2.2 Frequency modulation 10.5.2.3 Phase modulation 10.5.2.4 Amplitude shift keying 10.5.2.5 Frequency shift keying 10.5.2.6 Phase shift keying 10.5.3 Demodulation 10.5.3.1 Amplitude demodulation 10.5.3.2 Frequency and phase demodulation 10.5.4 Encoding and decoding 10.5.4.1 Unipolar and bipolar encoding 10.5.4.2 Biphase encoding 10.5.4.3 Manchester code 10.6 RFIDs and embedded sensors 10.7 Sensor networks 10.8 Problems 11 Interfacing methods and circuits 11.1 Introduction 11.2 Amplifiers 11.2.1 The operational amplifier 11.2.1.1 Differential voltage gain 11.2.1.2 Common-mode voltage gain 11.2.1.3 Bandwidth 11.2.1.4 Slew rate 11.2.1.5 Input impedance 11.2.1.6 Output impedance 11.2.1.7 Temperature drift and noise 11.2.1.8 Power requirements 11.2.2 Inverting and noninverting amplifiers 11.2.2.1 The inverting amplifier 11.2.2.2 The noninverting amplifier 11.2.3 The voltage follower 11.2.4 The instrumentation amplifier 11.2.5 The charge amplifier 11.2.6 The integrator and the differentiator 11.2.7 The current amplifier 11.2.8 The comparator 11.3 Power amplifiers 11.3.1 Linear power amplifiers 11.3.2 PWM and PWM amplifiers 11.4 Digital circuits 11.5 A/D and D/A converters 11.5.1 A/D conversion 11.5.1.1 Threshold digitization 11.5.1.2 Threshold voltage-to-frequency conversion 11.5.1.3 True A/D converters 11.5.1.4 Dual-slope A/D converter 11.5.1.5 Successive approximation A/D 11.5.1.6 Flash analog-to-digital converter 11.5.2 D/A conversion 11.5.2.1 Resistive ladder network D/A conversion 11.5.2.2 PWM D/A conversion 11.5.2.3 Frequency-to-voltage (F/V) D/A conversion 11.6 Bridge circuits 11.6.1 Sensitivity 11.6.2 Bridge output 11.7 Data transmission 11.7.1 Four-wire transmission 11.7.2 Two-wire transmission for passive sensors 11.7.3 Two-wire transmission for active sensors 11.7.4 Digital data transmission protocols and buses 11.8 Excitation methods and circuits 11.8.1 Linear power supplies 11.8.2 Switching power supplies 11.8.3 Current sources 11.8.4 Voltage references 11.8.5 Oscillators 11.8.5.1 Crystal oscillators 11.8.5.2 LC and RC oscillators 11.9 Power harvesting 11.9.1 Solar power harvesting 11.9.2 Thermal gradient power harvesting 11.9.3 Magnetic induction and RF power harvesting 11.9.4 Power harvesting from vibrations 11.10 Noise and interference 11.10.1 Inherent noise 11.10.2 Interference 11.11 Problems 12 Interfacing to microprocessors 12.1 Introduction 12.2 The microprocessor as a general-purpose controller 12.2.1 Architecture 12.2.2 Addressing 12.2.3 Execution and speed 12.2.4 Instruction set and programming 12.2.5 Input and output 12.2.6 Clock and timers 12.2.7 Registers 12.2.8 Memory 12.2.9 Power 12.2.10 Other peripherals and functionalities 12.2.11 Programs and programmability 12.3 General requirements for interfacing sensors and actuators 12.3.1 Signal level 12.3.2 Impedance 12.3.3 Frequency and frequency response 12.3.4 Input signal conditioning 12.3.4.1 Offset 12.3.4.2 Scaling 12.3.4.3 Isolation 12.3.4.4 Loading 12.3.5 Output signals 12.4 Errors 12.4.1 Resolution errors 12.4.2 Computation errors 12.4.3 Sampling and quantization errors 12.4.4 Conversion errors 12.5 Problems Appendix A. Least squares polynomials and data fitting A.1 Linear least square data fitting A.2 Parabolic least squares fit Appendix B. Thermoelectric reference tables B.1 Type J thermocouples (iron/constantan) B.2 Type K thermocouples (chromel/alumel) B.3 Type T thermocouples (copper/constantan) B.4 Type E thermocouples (chromel/constantan) B.5 Type N thermocouples (nickel/chromium–silicon) B.6 Type B thermocouples (platinum [30%]/rhodium–platinum) B.7 Type R thermocouples (platinum [13%]/rhodium–platinum) B.8 Type S thermocouples (platinum [10%]/rhodium–platinum) Appendix C. Computation on microprocessors C.1 Representation of numbers on microprocessors C.1.1 Binary numbers: unsigned integers C.1.2 Signed integers C.1.3 Hexadecimal numbers C.2 Integer arithmetic C.2.1 Addition and subtraction of binary integers C.2.2 Multiplication and division C.2.2.1 Binary integer multiplication C.2.2.2 Binary integer division C.3 Fixed point arithmetic Answers to problems Index Back Cover