Transport Phenomena in Microfluidic Systems

Cover
Title Page
Copyright
Contents
About the Author
Preface
Acknowledgement
List of Figures
List of Tables
Chapter 1 Introduction
	1.1 History
	1.2 Definition
	1.3 Analogy of Microfluidics with Computing Technology
	1.4 Interdisciplinary Aspects of Microfluidics
		1.4.1 Microfluidics in Nature
		1.4.2 Unit Systems in Small Scales
	1.5 Overall Benefits of Microdevices
		1.5.1 Importance of Flow through Microchannels
		1.5.2 Multiphase Microfluidics
		1.5.3 Microfluidic Applications
		1.5.4 Consumer Products
	1.6 Microscopic Scales for Liquids and Gases
	1.7 Physics at Micrometric Scale
		1.7.1 Macromolecules
	1.8 Scaling Laws
		1.8.1 Application of Scaling Law to Natural System
		1.8.2 Scaling Laws in Microsystems
		1.8.3 Scaling Laws Limitation
	1.9 Shrinking of Human Beings
	Problems
	References
	Supplemental Reading21
Chapter 2 Channel Flow
	2.1 Introduction
	2.2 Hydraulic Resistance
	2.3 Two Connected Straight Channels
		2.3.1 Straight Channels in Series
		2.3.2 Straight Channels in Parallel
	2.4 Equivalent Circuit Theory
	2.5 Reynolds Number
		2.5.1 Microsystems with Only One Length Scale
		2.5.2 Microsystems with Two Length Scales
	2.6 Governing Equation for Arbitrary-Shaped Channel
		2.6.1 Elliptic Cross-section
		2.6.2 Circular Cross-Section
		2.6.3 Equilateral Triangular Cross-section
		2.6.4 Rectangular Cross-section
		2.6.5 Infinite Parallel-plate Channel
	2.7 Summary of Hydraulic Resistance in Straight Channels
	2.8 Viscous Dissipation of Energy
		2.8.1 Energy Equation in Microgeometries
	2.9 Compliance
		2.9.1 Compliance due to Entrapped Gas
		2.9.2 Soft-Walled Channel Flow
	Problems
	Supplemental Reading
Chapter 3 Transport Laws
	3.1 Introduction
	3.2 Boundary Slip
	3.3 Slip Flow Boundary Condition in Gases
		3.3.1 Accommodation Coefficient
		3.3.2 Slip Model Derivation
	3.4 Slip Flow Boundary Condition in Liquids
		3.4.1 Flow Rate Measurements
		3.4.2 Hydrodynamic Force Measurement
		3.4.3 Velocity Measurements
		3.4.4 Molecular Dynamics Simulation
		3.4.5 Other Techniques
	3.5 Physical Parameters Affecting Slip
		3.5.1 Surface Roughness
		3.5.2 Surface Wettability
		3.5.3 Shear Rate
		3.5.4 Dissolved Gases and Bubbles
		3.5.5 Polarity
	3.6 Possible Liquid Slip Mechanism
	3.7 Thermal Creep Phenomena
		3.7.1 Knudsen Compressor
	3.8 Couette Flow with Slip Flow Boundary Condition
	3.9 Compressibility Effect in Microscale Flows
		3.9.1 Compressibility Effects of Flow between Parallel Plates
	3.10 Slip Flow between Two Parallel Plates
	3.11 Fluid Flow Modeling
		3.11.1 Continuum-Based Model
		3.11.2 Deterministic Molecular Models
		3.11.3 Statistical Molecular Model
		3.11.4 Liouville Equation
		3.11.5 Boltzmann Equation
		3.11.6 Direct Simulation Monte Carlo (DSMC) Method
	Problems
	References
	Supplemental Reading
Chapter 4 Diffusion, Dispersion, and Mixing
	4.1 Introduction
	4.2 Random Walk Model of Diffusion
	4.3 Stokes-Einstein Law
	4.4 Fick\'s Law of Diffusion
	4.5 Diffusivity and Mass Transport Nomenclature
	4.6 Governing Equation for Multicomponent System
	4.7 Characteristic Parameters
	4.8 Diffusion Equation
		4.8.1 Fixed Planar Source Diffusion
		4.8.2 Constant Planar Source Diffusion
	4.9 Taylor Dispersion
		4.9.1 Taylor Dispersion in Microchannels
		4.9.2 H-Filter
	4.10 Micromixer
		4.10.1 Ring-Shaped Micromixer
		4.10.2 Micromixer Based on Size Reduction
		4.10.3 Hydrodynamics Focusing
		4.10.4 Chaotic Mixing
		4.10.5 Droplet Formation and Chaotic Advection
	4.11 Convective Diffusion
		4.11.1 Convective Diffusion Layer
		4.11.2 Order of Magnitude Estimate
	4.12 Detailed Analysis
		4.12.1 Flow Past a Reacting Flat Plate
		4.12.2 Channel Flow with Soluble or Rapidly Reacting Walls
	4.13 Reverse Osmosis
		4.13.1 Reverse Osmosis Channel Flow
	Problems
	Supplemental Reading
Chapter 5 Surface Tension-Dominated Flows
	5.1 Surface Tension
	5.2 Gibbs Free Energy and Surface Tension
		5.2.1 Definition
	5.3 Microscopic Model of Surface Tension
	5.4 Young-Laplace Equation
	5.5 Contact Angle
		5.5.1 Definition of Contact Angle
		5.5.2 Young\'s Equation for Contact Angle
	5.6 Dynamic Contact Angle
	5.7 Superhydrophobicity and Superhydrophilicity
		5.7.1 Effect of Roughness
		5.7.2 Effect of Surface Inhomogeneities
		5.7.3 Effect of Surfactant
		5.7.4 Motion of Drops at Boundary of Hydrophilic-Hydrophobic Surface
	5.8 Microdrops
		5.8.1 Wetting
	5.9 Capillary Rise and Dimensionless Numbers
		5.9.1 Capillary Rise Time
	5.10 Coating Flows
	5.11 Enhanced Oil Recovery
	5.12 Classification of Surface Tension Gradient-Driven Flow
	5.13 Boundary Conditions
	5.14 Thermocapillary Motion
		5.14.1 DNA Arrays
	5.15 Diffusocapillary Flow
	5.16 Electrowetting
		5.16.1 Electrowetting-Based Microactuator
	5.17 Marangoni Convection in Drops
	5.18 Marangoni Instability
	5.19 Micropropulsion System
	5.20 Capillary Pump
		5.20.1 Advancement Time of Capillary Pump
	5.21 Thermocapillary Motion of Droplets
	5.22 Thermocapillary Pump
	5.23 Taylor Flows
		5.23.1 Practical Applications
		5.23.2 Flow Patterns
	5.24 Two-Phase Liquid-Liquid Poiseuille Flow
	5.25 Hydrodynamics of Taylor Flow
		5.25.1 Liquid Film Thickness
	5.26 Plug Motion in Capillary
	5.27 Clogging Pressure
	5.28 Digital Microfluidics
	Problems
	References
	Supplemental Reading
Chapter 6 Charged Species Flow
	6.1 Introduction
	6.2 Electrical Conductivity and Charge Transport
	6.3 Electrohydrodynamic Transport Theory
		6.3.1 Transport Equation for Dilute Binary Electrolyte
	6.4 Electrolytic Cell Example
	6.5 The Electric Double Layer and Electrokinetic Phenomena
	6.6 Debye Layer Potential Distribution
		6.6.1 Surface Charge and Debye Layer Capacitance
	6.7 Electrokinetic Phenomena Classification
	6.8 Electroosmosis
		6.8.1 Electroosmotic Velocity
		6.8.2 Cylindrical Channel EO Flow
	6.9 Exact Expression for Cylindrical Channel EO Flow
		6.9.1 Small Debye Length
		6.9.2 Large Debye Length
		6.9.3 Debye Layer Overlap
	6.10 EO Pump
		6.10.1 Many-Channel EO Pump
		6.10.2 Cascade EO Pump
	6.11 EO Flow in Parallel Plate Channel
	6.12 Electroosmosis and Forced Convection
	6.13 Electrophoresis
		6.13.1 Charged Particle in an Electrolyte
		6.13.2 Capillary Electrophoresis
		6.13.3 Debye Layer Screening
	6.14 Dielectrophoresis
	6.15 Polarization and Dipole Moments
		6.15.1 DC Dielectrophoresis
	6.16 Point Dipole in a Dielectric Fluid
	6.17 Dielectric Sphere in a Dielectric Fluid: Induced Dipole
	6.18 Dielectrophoretic Force on a Dielectric Sphere
	6.19 Dielectrophoretic Trapping of Particles
	6.20 AC Dielectrophoretic Force on a Dielectric Sphere
		6.20.1 Crossover Frequency
	Problems
	Supplemental Reading275
Chapter 7 Magnetism and Microfluidics
	7.1 Introduction
	7.2 Magnetism Nomenclature
	7.3 Magnetic Beads
	7.4 Magnetic Bead Characterization
	7.5 Magnetostatics
	7.6 Magnetophoresis
		7.6.1 Magnetophoresis for Biodetection
		7.6.2 Magnetophoresis for Bioseparation
	7.7 Magnetic Force on Particles
	7.8 Magnetic Particle Motion
		7.8.1 Single-Bead System
		7.8.2 Many-Bead System
	7.9 Magnetic Field Flow Fractionation
	7.10 Ferrofluidic Pumps
	7.11 Magnetic Sorting and Separation
	7.12 Magneto-Hydrodynamics
	7.13 Governing Equations for MHD
		7.13.1 Nondimensionalization
		7.13.2 DC MHD Micropump
		7.13.3 AC MHD Micropump
	Problems
	Reference
	Supplemental Reading
Chapter 8 Microscale Conduction
	8.1 Introduction
	8.2 Energy Carriers
	8.3 Scattering Mechanism
	8.4 Nonequilibrium Conditions
	8.5 Time and Length Scales
	8.6 Scale Effects
		8.6.1 Approach Details (Methodology)
	8.7 Fourier\'s Law
	8.8 Hyperbolic Heat Conduction Equation
		8.8.1 Fourier\'s Conduction in Semi-Infinite Solid
		8.8.2 Hyperbolic Conduction in Semi-Infinite Solid
	8.9 Kinetic Theory
	8.10 Heat Capacity
		8.10.1 Electron Heat Capacity
		8.10.2 Phonon Heat Capacity
		8.10.3 Electron Thermal Conductivity in Metals
		8.10.4 Lattice Thermal Conductivity
		8.10.5 Scale Effects on Thermal Conductivity
	8.11 Boltzmann Transport Theory
		8.11.1 Fourier\'s Heat Conduction Equation
		8.11.2 Hyperbolic Heat Conduction Equation
	8.12 Microscale Two-Step Models
	8.13 Thin Film Conduction
	References
Chapter 9 Microscale Convection
	9.1 Introduction
	9.2 Scaling Analysis
		9.2.1 Brinkman Number
	9.3 Laminar Fully Developed Nusselt Number
	9.4 Why Microchannel Heat Transfer
	9.5 Gases versus Liquid Flow in Microchannels
	9.6 Temperature Jump
	9.7 Couette Flow with Viscous Dissipation
	9.8 Isothermal Parallel Plate Channel Flow without Viscous Heating
	9.9 Large Parallel Plate Flow without Viscous Heating: Uniform Surface Flux
	9.10 Fully Developed Flow in Microtubes: Uniform Surface Flux
	9.11 Convection in Isothermal Circular Tube with Viscous Heating
	9.12 Flow Boiling Heat Transfer in Mini-/Microchannels
		9.12.1 Minichannel versus Microchannel
		9.12.2 Nucleate and Convective Boiling
		9.12.3 Dryout Incipience Quality
		9.12.4 Saturated Flow Boiling Heat Transfer Correlation
		9.12.5 SubCooled Flow Boiling Heat Transfer Correlation
	9.13 Condensation Heat Transfer in Mini-/Microchannel
		9.13.1 Condensation Flow Regimes
		9.13.2 Condensation Heat Transfer Correlation
	Problems
	References
	Supplemental Reading
Chapter 10 Microfabrication
	10.1 Introduction
	10.2 Microfabrication Environment
	10.3 Functional Materials
		10.3.1 Monocrystalline Silicon
		10.3.2 Polysilicon
		10.3.3 Silicon Dioxide
		10.3.4 Silicon Nitride
		10.3.5 Metals
		10.3.6 Polymers
	10.4 Surface Preparation
	10.5 General Micromachining Procedure
	10.6 Photolithography
		10.6.1 Photoresist Deposition
		10.6.2 Positioning
		10.6.3 Exposure
		10.6.4 Development
	10.7 Subtractive Techniques
		10.7.1 Wet Etching
		10.7.2 Anisotropic KOH Etching
		10.7.3 Dry Etching
		10.7.4 Deep Reactive Ion Etching
	10.8 Additive Techniques
		10.8.1 Physical Vapor Deposition
		10.8.2 Chemical Vapor Deposition
		10.8.3 Doping
		10.8.4 Electrolytic Deposition
	10.9 Example of a Silicon Membrane Fabrication
	10.10 PDMS-Based Molding
		10.10.1 Example of Microchannel Fabrication
		10.10.2 Soft Lithography
		10.10.3 Replica Molding
	10.11 Sealing
		10.11.1 Anodic Field-Assisted Bonding
		10.11.2 Direct Bonding
		10.11.3 Indirect Bonding
	10.12 Laser Microfabrication Techniques
		10.12.1 Minimum Spot Size
		10.12.2 Physical Mechanism
	Problems
	Supplemental Reading
Chapter 11 Microscale Measurements
	11.1 Introduction
	11.2 Microscale Velocity Measurement
	11.3 PIV Fundamentals
		11.3.1 Implementation Issues
		11.3.2 Recording of the Particle Images
		11.3.3 Evaluation of Image Pairs
		11.3.4 Peak Detection and Displacement Estimation
		11.3.5 Data Validation
		11.3.6 Dynamic Velocity Range
		11.3.7 Optimum Pulse Separation Time
		11.3.8 Image Preprocessing
		11.3.9 Advanced PIV Interrogation Schemes
		11.3.10 Accuracy of PIV Measurements
	11.4 Micro-PIV System
		11.4.1 Volume Illumination
		11.4.2 Fluorescence
		11.4.3 Seeding Particles
		11.4.4 Particles Dynamics
		11.4.5 Brownian Motion
		11.4.6 Microscope Recording and Imaging
		11.4.7 Resolution and Depth of Field
		11.4.8 Measurement Depth
		11.4.9 Particle Visibility
		11.4.10 Data Interrogation in μ-PIV
	11.5 Temperature Measurement
		11.5.1 3ω Technique
		11.5.2 Scanning Thermal Microscope Based on AFM
		11.5.3 Transient Thermoreflectance Technique
		11.5.4 Microlaser-Induced Fluorescence Thermometry
	References
	Supplemental Reading
Chapter 12 Microscale Sensors and Actuators
	12.1 Introduction
	12.2 Flow Control
		12.2.1 Applications of Flow Control
		12.2.2 Flow Control Implementation Strategy
		12.2.3 Actuator Requirements for Flow Control
	12.3 Actuator Classification
		12.3.1 Microsynthetic Jet Actuator
		12.3.2 Microballoon Actuator
		12.3.3 Microflap Actuator
	12.4 Shear Stress Sensors
		12.4.1 Sensor Requirements for Turbulent Flow Control
		12.4.2 Benefits of MEMS-Based Sensors
	12.5 Classification of Shear Stress Sensors
		12.5.1 Shear Stress from Velocity Measurements
		12.5.2 Thermal Shear Stress Sensors
		12.5.3 Floating Element Shear Stress Sensors
		12.5.4 MEMS Skin Friction Fence
		12.5.5 Optical Shear Stress Sensors
	12.6 Calibration of Shear Stress Sensors
		12.6.1 Static Calibration
		12.6.2 Dynamic Calibration
	12.7 Uncertainty and Noise
	References
	Supplemental Reading
Chapter 13 Heat Pipe
	13.1 Introduction
	13.2 Applications of Heat Pipe
	13.3 Advantages of Heat Pipe
	13.4 Heat Pipe Operation
	13.5 Wick Structure
	13.6 Working Fluids and Structural Material of Heat Pipe
	13.7 Operating Temperature of Heat Pipe
	13.8 Ideal Thermodynamic Cycle of Heat Pipe
	13.9 Microheat Pipe
	13.10 Effective Thermal Conductivity
	13.11 Operating Limits
		13.11.1 Capillary Limitation
		13.11.2 Viscous Limit
		13.11.3 Sonic Limit
		13.11.4 Entrainment Limit
		13.11.5 Boiling Limit
	13.12 Cleaning and Charging
	Reference
	Supplemental Reading
Index
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