Fundamentals and Applications of Microfluidics (Artech House Microelectromechanical Systems Library)

486 Pages·2002·6.04 MB·English

by  Nam-Trung Nguyen

Fundamentals and Applications
of Microfluidics
ForalistingofrecenttitlesintheArtechHouseMicroelectromechanicalSystems
(MEMS)Series,turntothebackofthisbook.
Fundamentals and Applications
of Microfluidics
Nam-Trung Nguyen
Steven T. Wereley
Artech House
Boston • London
www.artechhouse.com
LibraryofCongressCataloging-in-PublicationData
Nguyen,Nam-Trung,1970-
Fundamentalsandapplicationsofmicrofluidics/Nam-TrungNguyen,StevenT.
Wereley.
p.cm.—(ArtechHousemicroelectromechanicalsystemsseries)
Includesbibliographicalreferencesandindex.
ISBN1-58053-343-4(alk.paper)
1.Fluidicdevices.2.Micromechanics. I.Wereley,StevenT.II.Title.III.Series.
TJ843.N452002
620.1'06—dc21 2002027961
BritishLibraryCataloguinginPublicationData
Nguyen,Nam-Trung
Fundamentalsandapplicationsofmicrofluidics.—(Artech
Housemicroelectromechanicalsystemsseries)
1.Fluidicdevices 2.Micromechanics
I.Title II.Wereley,StevenT
620.1'06
ISBN1-58053-343-4
CoverdesignbyIgorValdman
©2002ARTECHHOUSE,INC.
685CantonStreet
Norwood,MA02062
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tion.Useofaterminthisbookshouldnotberegardedasaffectingthevalidityofanytrade-
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InternationalStandardBookNumber:1-58053-343-4
LibraryofCongressCatalogCardNumber:2002027961
10987654321
Contents
Preface..........................................................................................................................xi
Acknowledgments.....................................................................................................xiii
Chapter 1 Introduction................................................................................................1
1.1 Microfluidics – The Emerging Technology...........................................................1
1.1.1 What Is Microfluidics?...............................................................................1
1.1.2 Commercial Aspects..................................................................................4
1.1.3 Scientific Aspects.......................................................................................6
1.2 Milestones of Microfluidics...................................................................................7
1.2.1 Device Development..................................................................................7
1.2.2 Technology Development..........................................................................8
1.3 Organization of the Book.......................................................................................9
References....................................................................................................................10
Chapter 2 Fluid Mechanics Theory...........................................................................11
2.1 Introduction..........................................................................................................11
2.1.1 Intermolecular Forces...............................................................................13
2.1.1 The Three States of Matter.......................................................................15
2.1.2 Continuum Assumption...........................................................................16
2.2 Continuum Fluid Mechanics at Small Scales.......................................................20
2.2.1 Gas Flows.................................................................................................21
2.2.2 Liquid Flows............................................................................................27
2.2.3 Boundary Conditions...............................................................................29
2.2.4 Parallel Flows...........................................................................................34
2.2.5 Low Reynolds Number Flows..................................................................40
2.2.6 Entrance Effects.......................................................................................42
2.2.7 Surface Tension........................................................................................45
2.3 Molecular Approaches.........................................................................................47
2.3.1 MD...........................................................................................................48
2.3.2 DSMCTechnique.....................................................................................51
2.4 Electrokinetics.....................................................................................................53
2.4.1 Electro-Osmosis.......................................................................................54
2.4.2 Electrophoresis.........................................................................................57
2.4.3 Dielectrophoresis.....................................................................................60
2.5 Conclusion...........................................................................................................62
Problems.......................................................................................................................64
References....................................................................................................................65
Chapter 3 Fabrication Techniques for Microfluidics..............................................67
v
vi Fundamentals and Applications of Microfluidics
3.1 Basic Microtechniques.........................................................................................67
3.1.1 Photolithography......................................................................................67
3.1.2 Additive Techniques................................................................................69
3.1.3 Subtractive Techniques............................................................................78
3.1.4 Pattern Transfer Techniques.....................................................................80
3.2 Silicon-Based Micromachining Techniques........................................................82
3.2.1 Silicon Bulk Micromachining..................................................................82
3.2.2 Silicon Surface Micromachining..............................................................90
3.3 Polymer-Based Micromachining Techniques......................................................98
3.3.1 Thick Resist Lithography.........................................................................98
3.3.2 Polymeric Surface Micromachining.......................................................104
3.3.3 Soft Lithography....................................................................................107
3.3.4 Microstereo Lithography........................................................................112
3.3.5 Micromolding.........................................................................................116
3.4 Other Micromachining Techniques....................................................................118
3.4.1 Subtractive Techniques..........................................................................118
3.4.2 Additive Techniques..............................................................................121
3.5 Assembly and Packaging of Microfluidic Devices............................................122
3.5.1 Wafer Level Assembly and Packaging..................................................122
3.5.2 Device Level Packaging.........................................................................124
3.6 Biocompatibility................................................................................................127
3.6.1 Material Response..................................................................................128
3.6.2 Tissue and Cellular Response................................................................128
3.6.3 Biocompatibility Tests...........................................................................128
Problems.....................................................................................................................129
References..................................................................................................................129
Chapter 4 Experimental Flow Characterization....................................................137
4.1 Introduction........................................................................................................137
4.1.1 Pointwise Methods.................................................................................138
4.1.2 Full-Field Methods.................................................................................138
4.2 Overview of Micro-PIV.....................................................................................144
4.2.1 Fundamental Physics Considerations of Micro-PIV..............................144
4.2.2 Special Processing Methods for Micro-PIV Recordings........................155
4.2.3 Advanced Processing Methods Suitable for
Both Micro/Macro-PIV Recordings....................................................................160
4.3 Micro-PIV Examples.........................................................................................163
4.3.1 Flow in a Microchannel.........................................................................163
4.3.2 Flow in a Micronozzle...........................................................................168
4.3.3 Flow Around a Blood Cell.....................................................................171
4.3.4 Flow in Microfluidic Biochip.................................................................173
4.3.5 Conclusions............................................................................................175
4.4 Extensions of the Micro-PIV technique.............................................................176
4.4.1 Microfluidic Nanoscope.........................................................................176
4.4.2 Microparticle Image Thermometry........................................................183
4.4.3 Infrared Micro-PIV................................................................................195
4.4.4 Particle Tracking Velocimetry...............................................................197
Contents vii
Problems.....................................................................................................................201
References..................................................................................................................201
Chapter 5 Microfluidics for External Flow Control..............................................207
5.1 Velocity and Turbulence Measurement.............................................................207
5.1.1 Velocity Sensors....................................................................................208
5.1.2 Shear Stress Sensors...............................................................................212
5.2 Turbulence Control............................................................................................222
5.2.1 Microflaps..............................................................................................223
5.2.2 Microballoon..........................................................................................224
5.2.3 Microsynthetic Jet..................................................................................225
5.3 Microair Vehicles..............................................................................................226
5.3.1 Fixed-Wing MAV..................................................................................227
5.3.2 Flapping-Wing MAV.............................................................................229
5.3.3 Microrotorcraft.......................................................................................232
5.3.4 Microrockets..........................................................................................234
Problems.....................................................................................................................243
References..................................................................................................................245
Chapter 6 Microfluidics for Internal Flow Control: Microvalves........................247
6.1 Design Considerations.......................................................................................250
6.1.1 Actuators................................................................................................250
6.1.2 Valve Spring..........................................................................................252
6.1.3 Valve Seat..............................................................................................253
6.1.4 Pressure Compensation Design..............................................................253
6.2 Pneumatic Valves..............................................................................................254
6.2.1 Pneumatic Actuators..............................................................................254
6.2.2 Design Examples....................................................................................255
6.3 Thermopneumatic Valves..................................................................................257
6.3.1 Thermopneumatic Actuators..................................................................257
6.3.2 Design Examples....................................................................................261
6.4 Thermomechanical Valves.................................................................................263
6.4.1 Solid-Expansion Valves.........................................................................263
6.4.2 Bimetallic Valves...................................................................................264
6.4.3 Shape-Memory Alloy Valves.................................................................268
6.5 Piezoelectric Valves...........................................................................................271
6.5.1 Piezoelectric Actuators...........................................................................271
6.5.2 Design Examples....................................................................................273
6.6 Electrostatic Valves...........................................................................................275
6.6.1 Electrostatic Actuators...........................................................................275
6.6.2 Design Examples....................................................................................279
6.7 Electromagnetic Valves.....................................................................................281
6.7.1 Electromagnetic Actuators.....................................................................281
6.7.2 Design Examples....................................................................................281
6.8 Electrochemical Valves.....................................................................................283
6.9 Capillary-Force Valves......................................................................................285
6.9.1 Capillary-Force Actuators......................................................................285
viii Fundamentals and Applications of Microfluidics
6.9.2 Design Examples....................................................................................288
Problems.....................................................................................................................289
References..................................................................................................................289
Chapter 7 Microfluidics for Internal Flow Control: Micropumps.......................293
7.1 Mechanical Pumps.............................................................................................295
7.1.1 Design Considerations...........................................................................295
7.1.2 Check-Valve Pumps...............................................................................297
7.1.3 Peristaltic Pumps....................................................................................304
7.1.4 Valveless Rectification Pumps...............................................................308
7.1.5 Rotary Pumps.........................................................................................313
7.1.6 Centrifugal Pumps..................................................................................315
7.1.7 Ultrasonic Pumps...................................................................................317
7.2 Nonmechanical Pumps.......................................................................................318
7.2.1 Electrical Pumps....................................................................................318
7.2.2 Surface Tension Driven Pumps..............................................................327
7.2.3 Chemical Pumps....................................................................................331
7.2.4 Magnetic Pumps.....................................................................................332
7.3 Scaling Law for Micropumps............................................................................334
Problems.....................................................................................................................336
References..................................................................................................................337
Chapter 8 Microfluidics for Internal Flow Control: Microflow Sensors.............343
8.1 Nonthermal Flow Sensors..................................................................................345
8.1.1 Differential Pressure Flow Sensors........................................................345
8.1.2 Drag Force Flow Sensors.......................................................................349
8.1.3 Lift Force Flow Sensors.........................................................................352
8.1.4 Coriolis Flow Sensors............................................................................352
8.1.5 Electrohydrodynamic Flow Sensors.......................................................353
8.2 Thermal Flow Sensors.......................................................................................354
8.2.1 Design Considerations...........................................................................354
8.2.2 Thermoresistive Flow Sensors...............................................................359
8.2.3 Thermocapacitive Flow Sensors............................................................363
8.2.4 Thermoelectric Flow Sensors.................................................................364
8.2.5 Thermoelectronic Flow Sensors.............................................................365
8.2.6 Pyroelectric Flow Sensors......................................................................368
8.2.7 Frequency Analog Sensors.....................................................................369
Problems.....................................................................................................................369
References..................................................................................................................370
Chapter 9 Microfluidics for Life Sciences and Chemistry....................................373
9.1 Microfilters........................................................................................................373
9.1.1 Design Considerations...........................................................................374
9.1.2 Design Examples....................................................................................376
9.2 Microneedles......................................................................................................379
9.2.1 Design Considerations...........................................................................380
9.2.2 Design Examples....................................................................................383
Contents ix
9.3 Micromixers.......................................................................................................386
9.3.1 Design Considerations...........................................................................389
9.3.2 Design Examples....................................................................................394
9.4 Microreactors.....................................................................................................401
9.4.1 Design Considerations...........................................................................403
9.4.2 Design Examples....................................................................................404
9.5 Microdispensers.................................................................................................423
9.5.1 Design Considerations...........................................................................424
9.5.2 Design Examples....................................................................................428
9.6 Microseparators.................................................................................................434
9.6.1 Design Considerations...........................................................................435
9.6.2 Gas Chromatography.............................................................................437
9.6.3 Liquid Chromatography.........................................................................439
9.6.4 Electrophoresis.......................................................................................440
Problems.....................................................................................................................442
References..................................................................................................................445
Appendix A List of Symbols.....................................................................................453
Appendix B Resources for Microfluidics Research................................................457
Appendix C Abbreviations of Different Plastics....................................................459
Appendix D Linear Elastic Deflection Models.......................................................461
About the Authors....................................................................................................463
Index..........................................................................................................................465