Understanding Third Edition Randy Frank Critical coverage of sensor fusion and energy harvesting; The latest details on wireless technology; The roles and challenges involved with sensor apps and cloud sensing, Greater emphasis on applications throughout the book; Dozens of figures and examples of current technologies from over 50 companies. Utilizing the latest in smart sensors, microelectromechanical systems (MEMS), and microelectronic research and development, readers get the technical and practical information they need to keep their designs and products on the cutting edge. Plus, engineers see how network (wired and wireless) connectivity continues to impact smart sensor development and the emerging need for trusted sensing. By combining information on micromachining and microelectronics, this is the first book that links these two important aspects of smart sensor technology so professionals don t have to keep multiple references on hand. This comprehensive resource also includes an extensive list of smart sensor acronyms and a glossary of key terms. With an effective blend of historical information and the latest content, the third edition of Understanding Smart Sensors provides a unique combination of foundational and future-changing information. Include bar code: ISBN-13: 978-1-60807-507-2 ISBN-10: 1-60807-507-9 BOSTON LONDON www.artechhouse.com Understanding SMART SENSORS Third Edition Third Edition Randy Frank is the president of Randy Frank and Associates in Scottsdale, Arizona. A wellestablished author and holder of three patents, Mr. Frank received his B.S. and M.S. in electrical engineering, as well as his M.B.A. in management, from Wayne State University in Detroit, Michigan. He is a Society of Automotive Engineers Fellow, former chairman and a member of the SAE Sensors Standards Committee, an IEEE Fellow, and a former member of the IEEE 1451 Smart Transducer Interface standards committee. SMART SENSORS Now in its third edition, Understanding Smart Sensors is the most complete, up-to-date, and authoritative summary of the latest applications and developments impacting smart sensors in a single volume. This thoroughly expanded and revised edition of an Artech bestseller contains a wealth of new material, including: Understanding SMART SENSORS Frank Randy Frank
Contents Preface xvii CHAPTER 1 Smart Sensor Basics 1 1.1 Introduction 1 1.2 Mechanical-Electronic Transitions in Sensing 3 1.3 Nature of Sensors 4 1.4 Integration of Micromachining and Microelectronics 9 1.5 Application Example 11 1.6 Summary 13 References 13 Selected Bibliography 14 CHAPTER 2 Micromachining 17 2.1 Introduction 17 2.2 Bulk Micromachining 18 2.3 Wafer Bonding 20 2.3.1 Silicon-on-Silicon Bonding 20 2.3.2 Silicon-on-Glass (Anodic) Bonding 21 2.3.3 Silicon Fusion Bonding 22 2.3.4 Wafer Bonding for More Complex Structures and Adding ICs 22 2.4 Surface Micromachining 24 2.4.1 Squeeze-Film Damping 26 2.4.2 Stiction 26 2.4.3 Particulate Control 26 2.4.4 Combinations of Surface and Bulk Micromachining 27 2.5 Other Micromachining Techniques 28 2.5.1 The LIGA Process 28 2.5.2 Dry Etching Processes 29 2.5.3 Micromilling 30 2.5.4 Lasers in Micromachining 31 2.6 Combining MEMS with IC Fabrication 32 2.7 Other Micromachined Materials 34 2.7.1 Diamond as an Alternate Sensor Material 34 vii
viii Contents 2.7.2 Metal Oxides and Piezoelectric Sensing 35 2.7.3 Films on Microstructures 36 2.7.4 Micromachining Metal Structures 37 2.7.5 Carbon Nanotube MEMS 38 2.8 MEMS Foundry Services and Software Tools 38 2.9 Application Example 40 2.10 Summary 42 References 42 Selected Bibliography 45 CHAPTER 3 The Nature of Semiconductor Sensor Output 47 3.1 Introduction 47 3.2 Sensor Output Characteristics 47 3.2.1 Wheatstone Bridge 48 3.2.2 Piezoresistivity in Silicon 49 3.2.3 Semiconductor Sensor Definitions 51 3.2.4 Static Versus Dynamic Operation 53 3.3 Other Sensing Technologies 53 3.3.1 Capacitive Sensing 53 3.3.2 Piezoelectric Sensing 54 3.3.3 The Hall-Effect 55 3.3.4 Chemical Sensors 56 3.3.5 Improving Sensor Characteristics 56 3.4 Digital Output Sensors 57 3.4.1 Incremental Optical Encoders 57 3.4.2 Digital Techniques 59 3.5 Noise/Interference Aspects 59 3.6 Low Power, Low Voltage Sensors 60 3.6.1 Impedance 61 3.7 Analysis of Sensitivity Improvement 61 3.7.1 Thin Diaphragm 61 3.7.2 Increase Diaphragm Area 61 3.7.3 Improve Topology 61 3.8 Application Example 62 3.9 Summary 64 References 64 CHAPTER 4 Getting Sensor Information Into the Microcontroller 67 4.1 Introduction 67 4.2 Amplification and Signal Conditioning 68 4.2.1 Instrumentation Amplifiers 69 4.2.2 Sleep-Mode Circuitry for Reducing Power 70 4.2.3 Rail to Rail Operational Amplifiers 71 4.2.4 Switched-Capacitor Amplifier 72
Contents ix 4.2.5 Barometer Application Circuit 73 4.2.6 4- to 20-mA Signal Transmitter 73 4.2.7 Schmitt Trigger 74 4.3 Separate Versus Integrated Signal Conditioning 75 4.3.1 Integrated Signal Conditioning 75 4.3.2 External Signal Conditioning 76 4.4 Digital Conversion 76 4.4.1 A/D Converters 77 4.4.2 Performance of A/D Converters 79 4.4.3 Implications of A/D Accuracy and Errors 80 4.5 On-Line Tool for Evaluating a Sensor Interface Design 81 4.6 Application Example 81 4.7 Summary 81 References 83 Selected Bibliography 84 CHAPTER 5 Using MCUs/DSPs to Increase Sensor IQ 85 5.1 Introduction 85 5.1.1 Other IC Technologies 85 5.1.2 Logic Requirements 86 5.2 MCU Control 86 5.3 MCUs for Sensor Interface 87 5.3.1 Peripherals 87 5.3.2 Memory 88 5.3.3 Input/Output 89 5.3.4 On-Board A/D Conversion 90 5.3.5 Power Saving Capability 90 5.3.6 Local Voltage or Current Regulation 92 5.4 DSP Control 92 5.4.1 Digital Signal Controllers 93 5.4.2 Field Programmable Gate Arrays 93 5.4.3 Algorithms Versus Look-Up Tables 93 5.5 Techniques and Systems Considerations 95 5.5.1 Linearization 95 5.5.2 PWM Control 96 5.5.3 Autozero and Autorange 96 5.5.4 Diagnostics 98 5.5.5 Reducing EMC/RFI 98 5.5.6 Indirect (Computed not Sensed) Versus Direct Sensing 98 5.6 Software, Tools, and Support 99 5.6.1 Design-in Support 99 5.7 Sensor Integration 100 5.8 Application Example 101 5.9 Summary 102 References 103
x Contents CHAPTER 6 Communications for Smart Sensors 107 6.1 Introduction 107 6.2 Background and Definitions 107 6.2.1 Definitions 108 6.2.2 Background 108 6.3 Sources (Organizations) and Standards 109 6.4 Automotive Protocols 112 6.4.1 CAN Protocol 113 6.4.2 LIN Protocol 115 6.4.3 Media Oriented Systems Transport 115 6.4.4 FlexRay 116 6.4.5 Other Automotive Protocol Aspects 116 6.5 Industrial Networks 117 6.5.1 Example Industrial Protocols 117 6.6 Protocols in Other Applications 117 6.7 Protocols in Silicon 118 6.7.1 MCU with Integrated CAN 118 6.7.2 LIN Implementation 120 6.7.3 Ethernet Controller 120 6.8 Transitioning Between Protocols 120 6.9 Application Example 121 6.10 Summary 123 References 123 Additional References 124 CHAPTER 7 Control Techniques 125 7.1 Introduction 125 7.1.1 Programmable Logic Controllers 125 7.1.2 Open- Versus Closed-Loop Systems 126 7.1.3 PID Control 126 7.2 State Machines 128 7.3 Fuzzy Logic 129 7.4 Neural Networks 132 7.5 Combined Fuzzy Logic and Neural Networks 134 7.6 Adaptive Control 134 7.6.1 Observers for Sensing 135 7.7 Other Control Areas 137 7.7.1 RISC Versus CISC 138 7.8 Impact of Artificial Intelligence 139 7.9 Application Example 141 7.10 Summary 142 References 143
Contents xi CHAPTER 8 Wireless Sensing 147 8.1 Introduction 147 8.1.1 The RF Spectrum 148 8.1.2 Spread Spectrum 149 8.2 Wireless Data and Communications 150 8.3 Wireless Sensing Networks 151 8.3.1 ZigBee 152 8.3.2 ZigBee-Like Wireless 152 8.3.3 ANT+ 152 8.3.4 6LoWPAN 153 8.3.5 Near Field Communication (NFC) 153 8.3.6 Z-Wave 153 8.3.7 Dust Networks 154 8.3.8 Other RF Wireless Solutions 154 8.3.9 Optical Signal Transmission 154 8.4 Industrial Wireless Sensing Networks 154 8.5 RF Sensing 155 8.5.1 Surface Acoustic Wave Devices 155 8.5.2 Radar 156 8.5.3 Light Detection and Ranging (LIDAR) 157 8.5.4 Global Positioning System 158 8.5.5 Remote Emissions Sensing 159 8.5.6 Remote Keyless Entry 159 8.5.7 Intelligent Transportation System 160 8.5.8 RF-ID 162 8.5.9 Other Remote Sensing 163 8.6 Telemetry 163 8.7 RF MEMS 166 8.8 Application Example 167 8.9 Summary 168 References 169 Selected Bibliography 171 CHAPTER 9 MEMS Beyond Sensors 173 9.1 Introduction 173 9.2 MEMS Actuators 174 9.2.1 Microvalves 174 9.2.2 Micromotors 176 9.2.3 Micropumps 177 9.2.4 Microdynamometer 179 9.2.5 Microsteam Engine 180 9.2.6 Actuators in Other Semiconductor Materials 180
xii Contents 9.3 Other Micromachined Structures 181 9.3.1 Cooling Channels 182 9.3.2 Microoptics 183 9.3.3 Microgripper 183 9.3.4 Microprobes 185 9.3.5 Micromirrors 186 9.3.6 Heating Elements 187 9.3.7 Thermionic Emitters 187 9.3.8 Field Emission Devices 188 9.3.9 Unfoldable Microelements 188 9.3.10 Micronozzles 190 9.3.11 Interconnects for Stacked Wafers 191 9.3.12 Nanoguitar 191 9.4 Application Example 192 9.5 Summary 194 References 194 CHAPTER 10 Packaging, Testing, and Reliability Implications of Smarter Sensors 197 10.1 Introduction 197 10.2 Semiconductor Packaging Applied to Sensors 197 10.2.1 Increased Pin Count 200 10.3 Hybrid Packaging 201 10.3.1 Ceramic Packaging and Ceramic Substrates 201 10.3.2 Multichip Modules 201 10.3.3 Dual-Chip Packaging 202 10.3.4 BGA Packaging 202 10.4 Common Packaging for Sensors 203 10.4.1 Plastic Packaging 204 10.4.2 Surface-Mount Packaging 204 10.4.3 Flip-Chip 205 10.4.4 Wafer-Level Packaging 206 10.4.5 3-D Packaging 207 10.5 Reliability Implications 209 10.5.1 The Physics of Failure 211 10.5.2 Wafer-Level Sensor Reliability 212 10.6 Testing Smarter Sensors 214 10.7 Application Example 214 10.8 Summary 215 References 216 CHAPTER 11 Mechatronics and Sensing Systems 219 11.1 Introduction 219 11.1.1 Integration and Mechatronics 219
Contents xiii 11.2 Smart-Power ICs 220 11.3 Embedded Sensing 222 11.3.1 Temperature Sensing 222 11.3.2 Current Sensing in Power ICs 225 11.3.3 Diagnostics 225 11.3.4 MEMS Relays 228 11.4 Other System Aspects 228 11.4.1 Batteries 229 11.4.2 Field Emission Displays 230 11.4.3 System Voltage Transients, Electrostatic Discharge, and Electromagnetic Interference 230 11.5 Application Example 232 11.6 Summary 233 References 233 CHAPTER 12 Standards for Smart Sensing 235 12.1 Introduction 235 12.2 Setting the Standards for Smart Sensors and Systems 235 12.3 IEEE 1451.1 237 12.3.1 Network-Capable Application Processor 237 12.3.2 Network Communication Models 240 12.4 IEEE 1451.2 241 12.4.1 STIM 241 12.4 2 Transducer Electronic Data Sheet 243 12.4.3 TII 245 12.4.4 Calibration/Correction Engine 245 12.4.5 Sourcing Power to STIMs 247 12.4.6 Representing Physical Units in the TEDS 248 12.5 IEEE 1451.3 249 12.6 IEEE 1451.4 250 12.7 IEEE 1451.5 250 12.8 IEEE P1451.6 252 12.9 IEEE 1451.7 252 12.10 Extending the System to the Network 252 12.11 Application Example 252 12.12 Summary 254 References 255 Selected Bibliography 256 CHAPTER 13 More Standards Impacting Sensors 257 13.1 Introduction 257 13.2 Sensor Plug and Play 257 13.3 Universal Serial Bus 259
xiv Contents 13.4 Development Tools Establish De Facto Standards 260 13.5 Alternate Standards 261 13.5.1 Airplane Networks 261 13.5.2 Automotive Safety Network 262 13.5.3 Another Automotive Safety Network 263 13.5.4 Automotive Sensor Protocol 264 13.6 Consumer/Cell Phone Apps 267 13.7 Application Example 268 13.8 Summary 269 References 269 CHAPTER 14 Sensor Fusion 271 14.1 Introduction 271 14.2 Sensor and Other Fusion Background 271 14.3 Automotive Applications 273 14.3.1 Ranging and Vision 274 14.3.2 Sensor Fusion for Virtual Sensors 275 14.3.3 Autonomous Driving 276 14.4 Industrial (Robotic) Applications 277 14.5 Consumer Applications 278 14.5.1 Fusion Software in the Sensor 278 14.5.2 Separate Fusion Software 279 14.5.3 Flexible Fusion Software 279 14.5.4 Agnostic Sensor Fusion 279 14.5.5 Simulation and Testing 280 14.6 Application Example 281 14.7 Summary 282 References 282 Selected Bibliography 284 CHAPTER 15 Energy Harvesting for Wireless Sensor Nodes 285 15.1 Introduction 285 15.2 Applications Drive Technology Implementation and Development 285 15.2.1 Structural Health Monitoring 285 15.2.2 Building Automations Systems 286 15.2.3 Industrial Applications 286 15.2.4 Automotive 286 15.2.5 Aircraft 286 15.2.6 Portable Consumer 287 15.2.7 Remote Distributed Applications 287 15.3 Complete System Consideration 287
Contents xv 15.4 EH Technologies 288 15.4.1 Thermoelectric EH 288 15.4.2 Piezoelectric EH 291 15.4.3 Photovoltaic EH 293 15.4.4 Electromagnetic EH 294 15.4.5 RF EH 294 15.4.6 Electromechanical EH 294 15.4.7 Multiple Energy Sources 295 15.4.8 Future Concepts 296 15.5 Energy Storage 297 15.5.1 Batteries 297 15.5.2 Ultracapacitors 298 15.6 Energy Budget 298 15.6.1 Power Management ICs 298 15.6.2 MCUs 299 15.6.3 Wireless Transmission 300 15.6.4 Sensor Power Consumption 301 15.7 Development Systems 302 15.8 Application Example 304 15.9 Summary 304 References 306 Selected Bibliography 308 CHAPTER 16 The Next Phase of Sensing Systems 309 16.1 Introduction 309 16.2 Future Sensor Plus Semiconductor Capabilities 310 16.2.1 Monolithic Versus Package-Level Integration 311 16.3 Future System Requirements 313 16.3.1 Sensing in Automobiles 313 16.3.2 Sensing in Smart Phones 315 16.3.3 Health Care Sensors 316 16.4 Software, Sensing, and the System 316 16.4.1 Sensor Apps 317 16.4.2 Cloud Sensing 319 16.5 Trusted Sensing 320 16.6 Alternate Views of Smart Sensing 321 16.7 The Smart Loop 322 16.8 Application Example 323 16.9 Summary 324 Acknowledgment 325 References 325 Selected Bibliography 327