Electrokinetics and Electrohydrodynamics in Microsystems

✍ Scribed by Antonio Ramos

• Publisher: Springer
• Year: 2011
• Tongue: English
• Leaves: 308
• Series: CISM International Centre for Mechanical Sciences 530
• Edition: 1st Edition.
• Category: Library

✦ Synopsis

Among the most promising techniques to handle small objects at the micrometer scale are those that employ electrical forces, which have the advantages of voltage-based control and dominance over other forces. The book provides a state-of-the-art knowledge on both theoretical and applied aspects of the electrical manipulation of colloidal particles and fluids in microsystems and covers the following topics: dielectrophoresis, electrowetting, electrohydrodynamics in microsystems, and electrokinetics of fluids and particles. The book is addressed to doctoral students, young or senior researchers, chemical engineers and/or biotechnologists with an interest in microfluidics, lab-on-chip or MEMS.

✦ Table of Contents

Cover......Page 1
CISM International Centre for Mechanical Sciences 530......Page 4
Electrokinetics and Electrohydrodynamics in Microsystems......Page 5
ISBN 9783709108994......Page 6
PREFACE......Page 8
Table of Contents......Page 10
1 Introduction......Page 12
2.1 Polarized Particle......Page 13
2.2 Dielectrophoresis......Page 15
2.3 Travelling wave dielectrophoresis......Page 17
2.4 Electrorotation......Page 18
3.1 Classical Electrode Configurations......Page 20
3.3 Single cell trapping......Page 23
4.1 Particle characterization......Page 25
4.2 DEP for microfluidic systems......Page 27
5 Nanoscale DEP......Page 29
5.1 Navier-Stoke’s equation and the Stoke’s drag force......Page 30
5.3 Electric field induced forces (electrohydrodynamics)......Page 31
5.4 Scaling laws......Page 32
5.5 Nano-particle separation......Page 33
Bibliography......Page 35
1.1 Charge and forces on charges......Page 40
1.2 Electric field and electrical potential......Page 41
2 Bound charges, polarisation and dielectrics......Page 42
2.2 Dielectrics......Page 43
2.3 Polarisation mechanisms......Page 45
2.4 The electric flux density......Page 46
3 Charge, currents and Ohm’s law......Page 47
3.1 Water electrolytes and conductivity......Page 48
3.2 Mobility and hydration radius......Page 49
4 Quasi-electrostatics: AC fields and complex permittivity......Page 50
4.2 Summary......Page 53
5.1 Orientational relaxation......Page 54
6.1 Interfacial polarisation......Page 58
6.2 The induced effective dipole moment of a particle......Page 59
6.3 The effective dipole moment of a spherical particle......Page 60
6.5 The effective dipole moment of an ellipsoidal particle......Page 64
7 Mixture theory......Page 66
Bibliography......Page 68
1 Introduction......Page 72
2 Force on an induced dipole: Dielectrophoresis......Page 73
2.1 Translational force on a dipole in a non-uniform field......Page 74
2.2 Dielectrophoresis in an AC field......Page 77
2.3 Dielectrophoretic behaviour......Page 78
2.4 A note on the direction of the DEP force......Page 80
2.5 Dielectrophoresis in a fluid......Page 81
3 Dielectrophoresis in a field with a spatially dependent phase......Page 82
3.1 Travelling wave Dielectrophoresis (twDEP)......Page 84
4 Torques: electrorotation and electro-orientation......Page 86
4.1 Electrorotation (ROT)......Page 87
4.2 Electroorientation......Page 89
5 Particle-particle interaction......Page 90
5.2 Induced dipoles......Page 91
Bibliography......Page 95
1 Introduction......Page 96
2.1 Basics of Wetting......Page 98
2.2 The Electrowetting Equation......Page 101
2.3 Electrochemical derivation......Page 102
2.4 Electromechanical interpretation and fine structure of the three-phase contact line......Page 103
2.5 Effect of AC signals and internal flows in AC electrowetting experiments......Page 107
2.6 Limiting effects: contact angle saturation and contact line instabilities......Page 112
2.7 Note: Electrocapillary effect and Lippmann experiment......Page 115
3.1 Electrowetting for microfluidic operations: dispensing, splitting, merging, mixing and transporting of drops......Page 117
3.2 Electrowetting-induced reduction of contact angle hysteresis......Page 120
3.3 Electrowetting on complex surfaces......Page 122
3.4 Electrowetting-assisted drop generation in microchannels......Page 125
3.5 Electrowetting and optical applications......Page 128
3.6 Other applications......Page 129
Bibliography......Page 132
1 Introduction......Page 138
1.1 EHD equations in the microscale......Page 140
1.2 Some concepts of electrical conduction in liquids......Page 142
1.3 Some concepts of pumps......Page 147
2.1 Injection micropump......Page 148
2.2 Conduction micropump......Page 153
2.3 Induction micropump......Page 159
2.4 Electroosmotic micropump......Page 164
2.5 AC Electroosmotic micropump......Page 169
3.1 Liquid electrical conductivity......Page 174
3.2 Mechanical characteristics......Page 177
3.3 Applications......Page 178
4 Concluding remarks......Page 179
Bibliography......Page 180
1 Introduction......Page 188
2.1 Ohmic model......Page 189
2.2 Maxwell stress......Page 192
2.3 Governing equations......Page 196
2.4 Model problems of electrohydrodynamic stability......Page 198
3 Electrokinetic Mixing Flow......Page 199
3.1 Linearized thin-layer equations......Page 202
3.2 Results of linear stability analysis......Page 205
4 Electrohydrodynamic cone-jet......Page 209
4.1 Operating diagram of a steady cone-jet......Page 211
4.2 Long-wavelength model......Page 213
4.3 Convective and absolute instability......Page 218
4.4 Pulsating cone-jet......Page 222
5 Concluding Remarks......Page 227
Bibliography......Page 228
1 Introduction......Page 232
2.1 Electrohydrodynamics in dielectric liquids......Page 237
2.2 Electrokinetics in electrolytes......Page 239
3.1 Flows around metal surfaces......Page 243
3.2 Flows around dielectric surfaces......Page 246
4 Standard Model for thin double layers......Page 247
4.1 Electrochemical relaxation......Page 248
4.2 Fluid flow......Page 249
4.3 Particle motion......Page 250
4.4 Symmetric geometries......Page 253
5 Double-layer models......Page 254
6.1 The complex potential......Page 259
6.2 Analytical example: Metal sphere in an AC field......Page 261
6.3 Numerical example: Metal cylinder in a microchannel......Page 263
7.1 Field-dependent mobility and aperiodic electrophoresis......Page 266
7.2 Induced-charge electrophoresis......Page 268
7.3 Dipolophoresis......Page 272
8.1 Linear electrophoresis......Page 274
8.2 Induced-charge electrophoresis......Page 277
9 Induced-charge electro-osmotic mixing......Page 281
10.1 Slip-driven microfluidic pumps......Page 285
10.2 DC versus AC electro-osmotic pumps......Page 287
10.3 Flows over ideally polarizable electrodes......Page 288
10.4 Fluid pumping by micro-electrode arrays......Page 290
11 Beyond the Standard Model......Page 297
Bibliography......Page 301