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Chemical Sensors: Simulation and Modeling Volume 2: Conductometric-Type Sensors

Book Description

Chemical sensors are integral to the automation of myriad industrial processes and everyday monitoring of such activities as public safety, engine performance, medical therapeutics, and many more. This 4 volume reference work covering simulation and modeling will serve as the perfect complement to Momentum Press's 6 volume reference works 'Chemical Sensors: Fundamentals of Sensing Materials' and 'Chemical Sensors: Comprehensive Sensor Technologies', which present detailed information related to materials, technologies, construction and application of various devices for chemical sensing. This 4 volume comprehensive reference work analyzes approaches used for computer simulation and modeling in various fields of chemical sensing and discusses various phenomena important for chemical sensing such as bulk and surface diffusion, adsorption, surface reactions, sintering, conductivity, mass transport, interphase interactions, etc. In this work it will be shown that theoretical modeling and simulation of the processes, being a basic for chemical sensors operation, could provide considerable progress in choosing both optimal materials and optimal configurations of sensing elements for using in chemical sensors. Each simulation and modeling volume in the present series reviews modeling principles and approaches peculiar to specific groups of materials and devices applied for chemical sensing. Volume 2: Conductometric-Type Sensors covers phenomenological modeling and computational design of conductometric chemical sensors based on nanostructured materials such as metal oxides, carbon nanotubes and graphene. This volume contains an overview of the approaches used to quantitatively evaluate characteristics of sensitive structures in which electric charge transport depends on the interaction between the surfaces of the structures and chemical compounds in the surrounding.

Table of Contents

  1. Cover
  2. Half Title
  3. Title
  4. Copyright
  5. Contents
  6. Preface
  7. About the Editor
  8. Contributors
  9. 1 Numerical Simulation of Electrical Responses to Gases in Advanced Structures
    1. 1 Introduction
    2. 2 Analytic and Numeric Modeling
    3. 2.1 Basic Equations
    4. 2.2 Analytical Approaches
    5. 2.3 Numerical Simulations
    6. 2.4 Verifi cation of Models
    7. 3 Resistive Sensors
    8. 3.1 Introductory Remarks
    9. 3.2 Polycrystalline Films
    10. 3.3 Nanostructured Films
    11. 3.4 Conductive Polymer Layers
    12. 3.5 Molecular Structures
    13. 4 Concluding Comments
    14. References
  10. 2 Co-Adsorption Processes and Quantum Mechanical Modeling of Gas-Sensing Effects
    1. 1 Introduction
    2. 2 Solid–Gas Interaction
    3. 2.1 Adsorption
    4. 2.2 Chemisorption
    5. 2.3 Electronic Transitions in Chemisorption
    6. 2.4 Chemisorption in Equilibrium, “Wolkenstein” Isotherm
    7. 2.5 Reaction Time
    8. 2.6 Charge Transfer Model (CTM)
    9. 3 Co-adsorption
    10. 3.1 Quantum Model
    11. 3.2 Statistical Model
    12. 3.3 Adsorption Time
    13. 4 Discussion
    14. 5 Summary
    15. 6 Nomenclature
    16. Dedication
    17. Acknowledgment
    18. References
  11. 3 Nanosensors: A Platform to Model the Sensing Mechanisms in Metal Oxides
    1. 1 Introduction
    2. 2 Toward a Better Description of Gas-Sensing Mechanisms in Metal Oxides: Oxygen Diffusion in Tin Dioxide Nanowires
    3. 2.1 Description of Oxygen Sensing Using Diffusion
    4. 2.2 Summary
    5. 3 Toward a Systematic Understanding of Photo-Activated Gas Sensors
    6. 3.1 Experimental Background
    7. 3.2 Theoretical Model of the Photo-Activated Response to Oxidizing Gases (NO2)
    8. 3.3 Comparison with Experiments
    9. 3.4 Other Target Gases
    10. 3.5 Summary
    11. 4 Conclusions
    12. Acknowledgments
    13. References
  12. 4 Surface State Models for Conductance Response of Metal Oxide Gas Sensors During Thermal Transients
    1. 1 Introduction
    2. 2 Surface-State–Based Models of Resistive Chemical Sensors
    3. 2.1 Depleted Surface
    4. 2.2 Enhanced Surface
    5. 3 Building a Chemical-Physical Sensor Model: From the Chemistry to the Resistance Variations
    6. 3.1 The Mechanism of Conduction in the Film: Effect of the Film Structure
    7. 3.2 Selection of a Model for Surface Potential Barrier Height as a Function of the Surface Charge: Solution of the Poisson Equation
    8. 3.3 Selection of a Model for the Evolution of the Surface Charge as a Function of the Surface Chemical Reactions
    9. 4 Surface State–Based Models for Chemical Resistive Sensors: Different Assumptions and Points of View
    10. 5 Developing a Treatable Gray Model from the Physical-Chemical Model
    11. 5.1 The Intrinsic Model
    12. 5.2 The Extrinsic Model: Contributions from Oxygen and Reducing Gas
    13. 5.3 Effects of Water Vapor
    14. 6 Conclusions
    15. Nomenclature
    16. References
  13. 5 Conductance Transient Analyses of Metal Oxide Gas Sensors on The Example of Spinel Ferrite Gas Sensors
    1. 1 Introduction
    2. 2 Salient Features of Gas–Solid Interaction during Gas Sensing
    3. 3 Experimental
    4. 4 Modeling the Conductance Transients during Response and Recovery
    5. 4.1 Derivation of Response and Recovery Conductance Transients Based on Langmuir Adsorption Isotherm
    6. 4.2 Nonlinear Fitting of Response and Recovery Transients
    7. 4.3 Variation of Response and Recovery Time Constants with Sensor Operating Temperature
    8. 4.4 Variation of the Estimated Fitted Parameters with Test Gas Concentration: Addressing the Selectivity Issue
    9. 5 Characteristic Features Observed in Resistance Transients
    10. 5.1 Investigations on Irreversible and Reversible Gas Sensing in Oxide Gas Sensors
    11. 5.2 Periodic Undulation of the Resistance Transients during Response and Recovery
    12. 5.3 Spikelike Features in Resistance Transients
    13. 6 Summary and Conclusions
    14. 7 Appendix
    15. 7.1 Solution of Eq. (5.36)
    16. 7.2 Solution of Eq. (5.42)
    17. 8 Nomenclature
    18. Acknowledgment
    19. References
  14. 6 Model of Thermal Transient Response of Semiconductor Gas Sensors
    1. 1 Introduction
    2. 2 Improvement in Selectivity of the Semiconductor Gas Sensor Using Transient Response
    3. 3 Model of Thermal Transient Response of Semiconductor Gas Sensors
    4. 3.1 Transient Response of Semiconductor Gas Sensors
    5. 3.2 Thermal Transient Response of Semiconductor Gas Sensors
    6. 3.3 Physical and Chemical Processes in the Semiconductor Gas Sensor Under Transient Response
    7. 4 Modeling of Gas Sensor Processes
    8. 4.1 Heat Conduction Processes
    9. 4.2 Chemical Reaction Processes
    10. 4.3 Diffusion Processes
    11. 4.4 Sensor Output
    12. 5 Calculation Methods
    13. 5.1 Heat Conduction
    14. 5.2 Gas Concentrations on the Sensor Surface
    15. 6 Calculated Transient Responses of Gas Sensors
    16. 6.1 Temperature Change on the Sensor Surface
    17. 6.2 Concentration Change of Substance in the Vicinity of the Sensor Surface
    18. 6.3 Comparison to Experimental Results
    19. 7 Application of the Model of Transient Response
    20. 7.1 Transient Responses Under Heating with Various Waveforms
    21. 7.2 Activation Energy Dependence of Transient Response
    22. 8 Conclusions
    23. References
  15. 7 Experimental Investigation and Modeling of Gas-Sensing Effect In Mixed Metal Oxide Nanocomposites
    1. 1 Introduction
    2. 2 Types of Mixed Metal Oxides
    3. 3 Synthesis of Metal Oxide Nanocomposites
    4. 4 Charge Transfer Processes and Conductivity
    5. 5 Conductivity Mechanism
    6. 6 Sensor Properties
    7. 7 Mechanism of Sensor Effect
    8. 7.1 Sensors Based on Single Nanofi bers
    9. 7.2 Polycrystalline Sensors
    10. 8 Modeling of the Sensory Effect for Reduced Gases
    11. 8.1 Qualitative Discussion of the Sensory Mechanism
    12. 8.2 Equilibrium Electronic Characteristics Of SnO2
    13. 8.3 Sensor Response
    14. 9 Conclusions
    15. Acknowledgment
    16. References
  16. 8 The Influence of Water Vapor on The Gas-Sensing Phenomenon of Tin Dioxide–Based Gas Sensors
    1. 1 Introduction
    2. 2 Direct Water Effects on Tin Dioxide–Based Gas Sensors
    3. 2.1 Undoped SnO2
    4. 2.2 Doped SnO2
    5. 3 Indirect Water Effects on Tin Dioxide–Based Gas Sensors
    6. 3.1 Reducing Gases
    7. 3.2 Oxidizing Gases
    8. 4 Phenomenological Model
    9. 5 Conclusions
    10. Acknowledgments
    11. References
  17. 9 Computational Design of Chemical Nanosensors: Transition Metal–Doped Single-Walled Carbon Nanotubes
    1. 1 Introduction
    2. 2 TM-Doped SWNTs as Nanosensors
    3. 3 Density Functional Theory
    4. 4 Kinetic Modeling
    5. 5 Nonequilibrium Green’s Function Methodology
    6. 5.1 Divacancy II
    7. 5.2 Divacancy I
    8. 5.3 Monovacancy
    9. 5.4 Target and Background Molecules
    10. 6 Sensing Property
    11. 7 Conclusions
    12. Acknowledgments
    13. References
  18. 10 Al-Doped Graphene for Ultrasensitive Gas Detection
    1. 1 Emerging Graphene-Based Gas Sensors
    2. 1.1 The Role of Aluminum Doping in Sensing Applications
    3. 2 Aluminum-Doped Graphene for CO Detection
    4. 2.1 Sensitivity Enhancement of CO Detection in Aluminum-Doped Graphene
    5. 2.2 Effect of Electric Field on CO Detection
    6. 2.3 Effect of Temperature on CO Detection
    7. 3 Aluminum-Doped Graphene for Formaldehyde Detection
    8. 3.1 Adsorption Enhancement with Aluminum Doping
    9. 3.2 Variation of Electronic Properties Induced by Adsorption
    10. 4 Aluminum-Doped Graphene for Detection of HF Molecules
    11. 4.1 Adsorption Enhancement of Aluminum-Doped Graphene
    12. 4.2 Adsorption Enhancement Mechanism
    13. 4.3 Effect of Electric Field on Adsorption
    14. 5 Conclusion and Future Challenges
    15. Acknowledgments
    16. References
  19. 11 Physics-Based Modeling of Sno2 Gas Sensors With Field-Effect Transistor Structure
    1. 1 Introduction
    2. 2 Physics-Based Modeling of the Nanobelts
    3. 3 Model Calibration
    4. 4 Analytical Model for Nanobelt Sensors
    5. 4.1 Case 1: Nanobelt with Ohmic Contacts in the Presence of Hydrogen
    6. 4.2 Case 2: Nanobelt with Ohmic Contacts in the Presence of Oxygen
    7. 4.3 Case 3: Nanobelt with Schottky Contacts in the Presence of Oxygen
    8. 5 Conclusion
    9. Appendix: Fabrication and Experimental Data
    10. References
  20. 12 Modeling and Simulation of Nanowire-Based Field-Effect Biosensors
    1. 1 Introduction
    2. 2 Homogenization
    3. 3 The Biofunctionalized Boundary Layer
    4. 3.1 The Site-Dissociation Model
    5. 3.2 Screening and Biomolecules
    6. 3.3 Summary
    7. 4 The Current Through the Nanowire Transducer
    8. 4.1 The Drift-Diffusion-Poisson System
    9. 4.2 Self-Consistent Simulations of Sensor Systems
    10. 5 Summary
    11. Acknowledgment
    12. References
  21. Index
  22. Ad Page
  23. Backcover