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Preface |
5 |
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Contents |
7 |
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Contributors |
12 |
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Micro-Fabrication of Gas Sensors |
15 |
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1.1 Introduction |
15 |
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1.2 Gas Sensors and MEMS Miniaturization Techniques |
17 |
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1.2.1 Silicon as a Sensor Material |
17 |
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1.2.2 Thermal Sensors and Actuators |
18 |
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1.2.3 Thermal Microstructures |
20 |
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1.3 Specific Sensor Examples |
25 |
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1.3.1 Heat Conductivity Sensors |
25 |
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1.3.2 Metal-Oxide-Based Gas Sensors |
29 |
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1.3.3 Field-Effect Gas Sensors |
33 |
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1.3.4 Thermal Infrared Emitters |
35 |
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1.4 Gas-Sensing Microsystems |
36 |
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1.4.1 Low False-Alarm-Rate Fire Detection |
37 |
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1.4.2 Air Quality Monitoring and Leak Detection |
41 |
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1.5 Industrialization Issues |
48 |
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1.5.1 Initiating a System-Level Innovation |
48 |
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1.5.2 Building Added-Value Lines |
48 |
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1.5.3 Mastering the MEMS Challenge |
50 |
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1.5.4 Cooperation Across Technical and Economic Interfaces |
51 |
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1.5.5 Creating Higher Added Value |
54 |
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1.6 Conclusions and Outlook |
54 |
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References |
55 |
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Electrical-Based Gas Sensing |
61 |
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2.1 Introduction |
61 |
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2.2 Metal Oxide Semiconductor Surfaces |
63 |
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2.2.1 Geometric Structures |
63 |
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2.2.2 Electronic Structures |
64 |
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2.3 Electrical Properties of Metal Oxide Semiconductor Surfaces |
64 |
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2.3.1 Semiconductor Statistics |
64 |
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2.3.2 Surface States |
66 |
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2.3.3 Surface Space Charge Region |
68 |
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2.3.4 Surface Dipoles |
71 |
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2.4 Conduction Models of Metal Oxides Semiconductor |
72 |
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2.4.1 Polycrystalline Materials with Large Grains |
74 |
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2.4.2 Polycrystalline Materials with Small Grains |
75 |
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2.4.3 Mono-crystalline Materials |
77 |
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2.5 Adsorption over Metal Oxide Semiconductor Surfaces |
79 |
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2.5.1 Physical and Chemical Adsorption |
79 |
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2.5.2 Surface Reactions Towards Electrical Properties |
81 |
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2.5.3 Catalysts and Promoters |
83 |
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2.6 Deposition Techniques |
84 |
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2.6.1 Three-Dimensional Nanostructures |
84 |
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2.6.2 Two-Dimensional Nanostructures |
85 |
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2.6.3 One-Dimensional Materials |
94 |
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2.7 Conductometric Sensor Fabrication |
98 |
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2.7.1 Substrate and Heater |
98 |
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2.7.2 Electrical Contacts |
102 |
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2.7.3 Heating Treatments |
103 |
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2.7.4 Dopings, Catalysts and Filters |
104 |
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2.8 Transduction Principles and Related Novel Devices |
106 |
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2.8.1 DC Resistance |
106 |
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2.8.2 AC Impedance |
108 |
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2.8.3 Response Photoactivation |
109 |
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2.9 Conclusions and Outlook |
113 |
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References |
113 |
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Capacitive-Type Relative Humidity Sensor with Hydrophobic Polymer Films |
122 |
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3.1 Introduction |
122 |
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3.2 Fundamental Aspects |
123 |
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3.2.1 Sorption Isotherms of Polymers |
123 |
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3.2.2 Water Sorption Behavior of Polymers |
124 |
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3.2.3 Effects of the Sorbed Water on the Dielectric Properties |
124 |
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3.3 Characterization of Polymers |
126 |
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3.3.1 Sorption Isotherms |
126 |
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3.3.2 FT-IR Measurement |
128 |
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3.3.3 Solvatochromism |
130 |
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3.3.4 Capacitance Changes with Water Sorption |
133 |
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3.3.5 Cross-Linked Polymer |
137 |
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3.4 Humidity-Sensors-Based Hydrophobic Polymer Thin Films |
143 |
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3.4.1 Poly-Methylmethacrylate-Based Humidity Sensor |
144 |
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3.4.1.1 Initial Performances |
144 |
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3.4.1.2 Temperature Dependence |
144 |
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3.4.1.3 Long-Term Stability |
145 |
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3.4.2 Characteristics of Cross-Linked PMMA-Based Sensor |
146 |
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3.4.2.1 Initial Performances |
146 |
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3.4.2.2 Temperature Dependence |
147 |
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3.4.2.3 Durability against Acetone Vapor |
147 |
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3.4.2.4 Long-Term Stability |
148 |
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3.4.3 Polysulfone-based Sensor |
149 |
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3.4.3.1 Initial Performances |
149 |
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3.4.3.2 Long-Term Stability |
150 |
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3.4.4 Acetylene-Terminated Polyimide-based Sensor |
151 |
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3.4.4.1 Determination of Curing Condition |
151 |
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3.4.4.2 Initial Performances |
154 |
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3.4.4.3 Temperature Dependence |
154 |
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3.4.4.4 Other Sensing Characteristics |
155 |
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3.4.5 Cross-Lined Fluorinated Polyimide-Based Sensor |
156 |
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3.4.5.1 Sensor Fabrication |
156 |
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3.4.5.2 Initial Performances |
156 |
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3.4.5.3 Long-Term Stability |
158 |
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3.4.6 Improvements Using MEMS Technology |
158 |
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3.4.6.1 Sensor Preparation |
159 |
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3.4.6.2 Sensing Characteristics |
160 |
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References |
162 |
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FET Gas-Sensing Mechanism, Experimental and Theoretical Studies |
165 |
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4.1 Introduction |
165 |
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4.2 Brief Summary of the Detection Mechanism of FET Devices |
166 |
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4.3 UHV Studies of FET Surface Reactions |
169 |
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4.4 TEM and SEM Studies of the Nanostructure of FET Sensing Layers |
172 |
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4.5 Mass Spectrometry for Atmospheric Pressure Studies |
173 |
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4.6 The Scanning Light Pulse Technology |
174 |
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4.7 DRIFT Spectroscopy for In Situ Studies of Adsorbates |
175 |
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4.8 Atomistic Modelling of Chemical Reactions on FET Sensor Surfaces |
180 |
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4.9 Nanoparticles as Sensing Layers in FET Devices |
183 |
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4.10 Summary and Outlook |
185 |
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References |
186 |
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Solid-State Electrochemical Gas Sensing |
192 |
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5.1 Introduction |
192 |
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5.2 Mixed-Potential-Type Sensors |
196 |
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5.2.1 High-Temperature-Type NOx Sensors |
196 |
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5.2.2 Improvement in NO2 Sensitivity by Additives |
200 |
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5.2.3 Hydrocarbon (C3H6 or CH4) Sensors |
202 |
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5.2.4 Use of Nanostructured NiO-Based Materials |
203 |
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5.2.5 Nanosized Au Thin-Layer for Sensing Electrode |
207 |
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5.3 Amperometric Sensors |
209 |
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5.4 Impedancemetric Sensors |
211 |
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5.4.1 Sensing of Various Gases in ppm Level |
211 |
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5.4.2 Environmental Monitoring of C3H6 in ppb Level |
212 |
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5.5 Solid-State Reference Electrode |
215 |
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5.6 Conclusions and Future Prospective |
216 |
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References |
217 |
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Optical Gas Sensing |
219 |
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6.1 Introduction |
219 |
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6.2 Spectroscopic Detection Schemes |
220 |
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6.3 Ellipsometry |
223 |
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6.4 Surface Plasmon Resonance |
226 |
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6.5 Guided-Wave Configurations for Gas Sensing |
231 |
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6.5.1 Integrated Optical SPR Sensors |
233 |
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6.5.2 Fiber Optic SPR Sensors |
233 |
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6.5.3 Conventional and Microstructured Fibers for Gas Sensing |
235 |
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6.6 Conclusions |
239 |
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References |
241 |
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Thermometric Gas Sensing |
247 |
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7.1 Detection of Combustible Gases |
247 |
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7.1.3 Combustion |
247 |
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7.1.3 Thermal Considerations during Combustion |
248 |
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7.1.3 Catalysis |
249 |
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7.1.3 Explosive Mixtures |
250 |
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7.2 Catalytic Sensing |
251 |
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7.2.1 Pellistors |
252 |
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7.2.1.1 Safe Detection of Explosive Mixtures |
254 |
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7.2.1.2 Calibration of Pellistor Sensors |
255 |
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7.2.1.3 Reliability Issues |
255 |
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7.2.1.4 Limitations in Use of Pellistors |
257 |
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7.2.2 Microcalorimeters in Enzymatic Reactions |
258 |
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7.3 Thermal Conductivity Sensors |
259 |
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7.4 Calorimetric Sensors Measuring Adsorption/Desorption Enthalpy |
261 |
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7.5 MEMS and Silicon Components |
261 |
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7.5.1 Thermal Considerations |
262 |
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7.5.2 Temperature Readout |
264 |
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7.5.3 Integrated Calorimetric Sensors |
266 |
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7.6 Sensor Arrays and Electronic Noses |
267 |
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References |
269 |
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Acoustic Wave Gas and Vapor Sensors |
271 |
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8.1 Introduction |
271 |
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8.1.4 Acoustic Waves in Elastic Media |
273 |
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8.1.4 Advantages of Acoustic-Wave-Based Gas-Phase Sensors |
276 |
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8.2 Thickness Shear Mode (TSM)-Based Gas Sensors |
277 |
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8.2.1 Quartz Crystal Microbalance (QCM)-Based Gas Sensors |
278 |
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8.2.1.1 Gas and Vapor Sensitivity |
279 |
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8.2.1.2 QCM Gas Sensor Performance |
282 |
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8.2.2 Thin-Film Resonator (TFR)-Based Gas Sensors |
286 |
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8.2.2.1 TFBAR Structures |
286 |
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8.2.2.2 SMR Structures |
286 |
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8.2.2.3 Gas and Vapor Sensitivity |
288 |
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8.2.2.4 Advantages and Disadvantages of TFRs Over QCMs |
288 |
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8.2.2.5 TFR Gas Sensor Performance |
289 |
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8.3 Surface Acoustic Wave (SAW)-Based Gas Sensors |
292 |
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8.3.1 Conventional SAW Gas Sensors |
295 |
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8.3.2 Multi-Layered SAW Gas Sensors |
296 |
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8.3.3 Gas and Vapor Sensitivity |
296 |
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8.3.3.1 Mechanical Perturbations |
297 |
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8.3.3.2 Acoustoelectric Perturbations |
298 |
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8.3.4 SAW Device Gas Sensor Performance |
301 |
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8.4 Concluding Remarks |
306 |
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References |
306 |
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Cantilever-Based Gas Sensing |
315 |
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9.1 Introduction to Microcantilever-Based Sensing |
315 |
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9.1.5 Early Approaches to Mechanical Sensing |
315 |
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9.1.5 Cantilever Sensors |
316 |
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9.1.5 Deflection Measurement |
317 |
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9.1.3.1 Piezoresistive Readout |
318 |
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9.1.3.2 Piezoelectric Readout |
318 |
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9.1.3.3 Capacitive Readout |
319 |
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9.1.3.4 Beam-Deflection Optical Readout |
319 |
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9.2 Modes of Operation |
320 |
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9.2.1 Static Mode |
320 |
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9.2.2 Dynamic Mode |
321 |
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9.3 Functionalization |
322 |
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9.4 Example of an Optical Beam-Deflection Setup |
323 |
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9.4.1 General Description |
323 |
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9.4.2 Cantilever-Based Electronic Nose Application |
324 |
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9.5 Applications of Cantilever-Based Gas Sensors |
326 |
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9.5.1 Gas Sensing |
326 |
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9.5.2 Chemical Vapor Detection |
328 |
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9.5.3 Explosives Detection |
329 |
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9.5.4 Gas Pressure and Flow Sensing |
331 |
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9.6 Other Techniques |
332 |
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9.6.1 Metal Oxide Gas Sensors |
332 |
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9.6.2 Quartz Crystal Microbalance |
333 |
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9.6.3 Conducting Polymer Sensors |
333 |
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9.6.4 Surface Acoustic Waves |
333 |
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9.6.5 Field Effect Transistor Sensors Devices |
334 |
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References |
335 |
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Index |
339 |
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