Micromachined Transducers Sourcebook

Description

Designed for a graduate-level course in micromachined devices, or as an introduction to the field for practicing engineers, this book presents an overview of the field, beginning with-micromachining approaches and including all major categories of transduction. It examines the fabrication of individual devices through the study of design issues and provides examples of key transducers, or structures, for comparison of performances obtainable through different approaches. Front Matter Preface Prologue Table Of Contents Chapter 1: Introduction And Overview 1. Introduction To Micromachined Devices 2. What Are Transducers? 3. Components Of Transducer Systems 4. What Are Micromachined Transducers? 5. When Does It Make Sense To "Micromachine"? 5.1 Scaling And Performance 5.2 Cost Reduction Issues 5.3 Complexity Of Micromachined Devices And Systems 6. Issues To Consider 7. What Are The Markets For Micromachined Transducers? 7.1 Micromachining As An "Enabling Technology" 7.2 Is The Market "Ready To Explode"? 8. Information Resources 8.1 On-Line Resources 8.2 Micromachined Transducers Meetings 8.3 Textbooks And Paper Collections 8.4 Journals 8.5 Theses 8.6 Patents 9. Conclusion Introduction And Overview References Chapter 2: Micromachining Techniques 1. Capabilities And Limitations Of Micromachining 2. Materials For Micromachining 2.1 Substrates 2.2 Additive Films And Materials 3. Micromachining Terms 4. General Properties Of Common Semiconductors 4.1 Mechanical Properties Of Silicon 4.2 Native Oxides Of Silicon And Other Semiconductors 4.3 Typical Silicon Wafer Types 5. "Bulk" (Subtractive) Processes 5.1 Wet Etching Of Silicon 5.1.1 Isotropic Wet Etching HF/HNO3/Acetic Acid ("HNA") 5.1.2 Anisotropic Wet Etching Alkali Hydroxide Etchants Ammonium Hydroxide Tetramethyl Ammonium Hydroxide (TMAH) Ethylene Diamine Pyrochatechol (EDP) Hydrazine Amine Gallates Ultrasonic Agitation In Wet Etching Etch-Stop Layers For Dopant-Selective Etchants 5.2 Wet Etching Of Gallium Arsenide And Related III-V Compounds 5.3 Electrochemical Modulation Of Wet Etching 5.3.1 Diode Junction Etch-Stop Junction Etch-Stop Using TMAH And Standard CMOS 5.3.2 Photon-Pumped Electrochemical Etching 5.4 Porous Silicon Formation 5.5 Other Bulk Wet Etch Techniques And Materials 5.5.1 Anisotropic Wet Etching Of Porous Aluminum 5.5.2 Anisotropic Wet Etching Of Quartz 5.5.3 Ion-Implant-Assisted Wet Etching 5.5.4 Ion-Track Damage-Assisted Wet Etching 5.5.5 One-Sided Wafer Etching 5.5.6 General Wet-Etching Concepts 5.6 Vapor-Phase Etching 5.6.1 Xenon Difluoride Etching 5.6.2 Interhalogen Etch Chemistries 5.6.3 Other Vapor-Etching Methods 5.7 Plasma/Reactive Ion Etching 5.7.1 Dopant-Dependent Plasma Etch Isotropy 5.7.2 High-Aspect-Ratio Dry Etching Methods Deep Reactive Ion Etching (DRIE) Cryogenic Dry Etching Magnetically Controlled Dry Etching Thermally Assisted Ion-Beam Etching 5.7.3 Variable Anisotropy Etch Processes Dry Etching Of Non-Silicon Semiconductors 5.8 Laser-Driven Bulk Processing 5.8.1 Laser Drilling 5.8.2 Laser Annealing 5.8.3 Laser-Driven Etching 6. "Surface" (Additive) Processes 6.1 Thin-Film Processes 6.1.1 Non-Metallic Thin-Films For Micromachining Silicon Dioxide Silicon Nitride Silicon Carbide Polycrystalline Diamond Polysilicon Other Semiconductors And Thin-Film Transistors Organic Compounds Sputtered Inorganic Thin-Films Spin-On Non-Metallic Thin-Films 6.1.2 Wet Etching Of Non-Metallic Thin-Films 6.1.3 Dry Etching Of Non-Metallic Thin-Films 6.1.4 Metallic Thin-Films For Micromachining Resistive Evaporation Electron-Beam Evaporation Sputter Deposition Comparison Of Evaporation And Sputtering Chemical Vapor Deposition Of Metals Selective Metal CVD Adhesion Layers For Metals 6.1.5 Wet Etching Of Metallic Thin-Films 6.1.6 Dry Etching Of Metallic Thin-Films 6.1.7 Lift-Off Patterning 6.2 Laser-Driven Deposition 6.3 Electrodeposition (Electroplating) 6.3.1 Electrodeposition Mechanisms 6.3.2 DC Electroplating 6.3.3 Pulsed Electroplating (“PEP”) 6.3.4 Agitation For Electroplating 6.3.5 "Black" Metal Films 6.3.6 "Electroless" Plating 6.3.7 Templates For Plating Self-Shorting Plating Patterns "Tear-Off" Electroplated Structures Photoimaged Plating Templates Synchrotron Exposed Templates: The LIGA Process RIE Or Plasma-Etched Templates 6.3.8 Template-Free Localized Electroplating 6.4 Selective Epitaxial Growth 7. Bonding Processes 7.1 Anodic Bonding 7.1.1 Anodic Bonding Using Deposited Glass 7.2 Silicon Fusion Bonding 7.3 Other Bonding Techniques 7.4 Compound Processes Using Bonding 8. Sacrificial Processes 8.1 Sticking Problems During Wet Release 8.1.1 Preventing Sticking During Wet Etch Release Phase-Change Release Methods Geometry/Process-Specific Release Methods Surface Treatment Release Methods 8.2 Example Sacrificial Processes 8.2.1 Sacrificial Liga ("SLIGA") Process 8.2.2 SIMOX As A Sacrificial Layer 8.2.3 Vapor-Phase Sacrificial Layer Etch 8.2.4 Plasma Etch Release Of Organic Sacrificial Layers 8.3 Template Replication 8.3.1 Injection Molding With Micromachined Templates 8.3.2 Plating-Based Template Replication 8.3.3 CVD-Based Template Replication 8.3.4 Ceramic Slurry-Based Template Replication 8.3.5 Preformed, Above Substrate Templates 9. Sealed Cavity Formation 9.1 Getters For Sealed Cavities 10. Surface Modification 11. Printing And Stereolithography 11.1 Screen Printing 11.2 Transfer Printing 11.3 Powder-Loaded Polymers For Printing 11.4 Three-Dimensional Lithography 11.5 Spatial Forming Via Transfer Printing 12. Other Micromachining Techniques 12.1 Sharp Tip Formation 12.1.1 Self-Occluding Masks 12.1.2 M1cromasking In Plasmas 12.1.3 Wet Etching 12.2 Chemical-Mechanical Polishing And Planarization 12.3 Electric Discharge Machining (EDM) 12.4 Abrasive Powder Machining 12.5 Precision Mechanical Machining 12.6 Scanning Probe Machining 12.7 Thermomigration 12.8 Photosensitive Glass Micromachining 12.9 Focused Ion-Beam Micromachining Micromachining Techniques References Chapter 3: Mechanical Transducers 1. Introduction 2. Basic Mechanics 2.1 Axial Stress And Strain 2.2 Shear Stress And Strain 2.3 Poisson'S Ratio 2.4 Commonly Used Deflection Equations For Microstructures 2.4.1 Static Beam Equations 2.4.2 Static Torsion Equations 2.4.3 Static Plate Equations 2.5 Dynamics 2.6 Thermal Noise 3. Mechanical Properties Of Materials 3.1 Material Failure 3.2 General Materials Considerations 3.3 Mechanical Characterization Of Thin-Films 3.3.1 Stress Measurement Uniform Stresses Nonuniform Stresses (Stress Gradients) 3.3.2 Measurement Of Other Mechanical Properties Direct Measurement Indirect Measurement 4. Basic Mechanisms And Structures 4.1 In-Plane Rotary Mechanisms 4.2 Out-Of-Plane Mechanisms 4.3 Structural Members 4.4 Bistable Mechanisms 4.5 Self-Assembly 5. Mechanical Sensors 5.1 Sensing Mechanisms 5.1.1 Resistive And Piezoresistive Strain Sensors Metallic Strain Gauges Semiconductor Strain Gauges 5.1.2 Piezojunction Effect 5.1.3 Piezoelectric Effect 5.1.4 Capacitive Sensing 5.1.5 Tunneling Sensing 5.2 Micromachined Mechanical Sensors 5.2.1 Micromachined Strain Gauges Implantable Strain Gauges Penetrating M1cro-Strain-Gauge Probe Single-Cell Strain Gauges Resonant Strain Gauges 5.2.2 Accelerometers Basic Accelerometer Concepts Force-Balanced Accelerometer Concepts Strain-Gauge Accelerometers Capacitive Accelerometers Force-Balanced Capacitive Accelerometers Piezoelectric Accelerometers Tunneling Accelerometers Latching Accelerometers Accelerometer Switch Arrays Multi-Axis Accelerometers 5.2.3 Micromachined Gyroscopes 5.2.4 Mechanical Pressure Sensors Pressure Measurement Units Piezoresistive Pressure Sensors Integrated Piezoresistive Pressure Sensors Surface Micromachined Piezoresistive Pressure Sensors Capacitive Pressure Sensors Pressure Switches Resonant Pressure Sensors 5.2.5 Microphones Piezoresistive Microphones Capacitive Microphones Piezoelectric Microphones Moving-Gate Fet Microphones 5.2.6 Tactile Sensors Piezoelectric Tactile Sensors Resistive Tactile Sensors Capacitive Tactile Sensors Optical Tactile Sensors Other Tactile Sensors 5.2.7 Biological Mechanosensors Biological Accelerometers Biological Tactile Sensors Biological Acoustic Sensors 6. Mechanical Actuators 6.1 Actuation Mechanisms 6.1.1 Electrostatic Actuation Electrostatic Cantilever Actuators Torsional Electrostatic Actuators Electrostatic Comb Drives Feedback Stabilization Of Electrostatic Actuators Electrostatic Rotary Micromotors Electrostatic Linear Micromotors Electrostatic Microgrippers Electrostatic Relays And Switches 6.1.2 Thermal Actuation Thermal Expansion Of Solids Bimorph Thermal Actuators Thermal Array Actuators Dielectric Loss Heating Of Thermal Bimorphs Volume Expansion And Phase-Change Actuators 6.1.3 Shape Memory Alloy Actuation 6.1.4 Pneumatic/Hydraulic Actuation 6.1.5 Piezoelectric Actuation 6.1.6 Magnetic Actuators 6.1.7 Chemical Actuators 6.1.8 Hybrid Actuation Schemes 6.1.9 Biological Actuators Cytoskeleton And Microtubules Cilia And Flagella Muscle 7. Mechanical Circuit Components 7.1 Mechanical Resonators 7.1.1 Cantilever Resonators 7.1.2 Lateral Resonators 7.1.3 Membrane Resonators 7.2 Mechanical Relays And RF Switches 7.2.1 General Purpose Relays Electrostatically Driven Relays Magnetically Driven Relays 7.2.2 RF Switches And Switched Circuits Mechanical Transducers References Chapter 4: Optical Transducers 1. Introduction 1.1 The Optical Spectrum 1.2 Units Relevant To Optical Transducers 1.3 Blackbody Radiation 2. Optical Sensors 2.1 Types Of Optical Sensors 2.1.1 Fundamental Principle Of Optical Detection 2.1.2 Direct Electronic Optical Sensors 2.1.3 Indirect Optical Sensors 2.1.4 Major Specifications For Photodetectors 2.2 Direct Electronic Optical Sensors 2.2.1 Light Absorption In Semiconductors 2.2.2 Band Structure Of Photosensors 2.2.3 Quantum Efficiency 2.2.4 Photoemiss1ve Sensors 2.2.5 Photoconduct1ve Sensors Gain Of Photoconductive Sensors Photoconductive Sensor Small-Signal Model Intrinsic Photoconductors Extrinsic Photoconductors Cadmium Sulfide And Cadmium Selenide Integrated Cdse Photoconductive Sensor Arrays Lead Sulfide And Lead Selenide Mercury Cadmium Telluride General Purpose Semiconductors Metal-Semiconductor-Metal Photoconductive Sensors 2.2.6 Junction-Based Photodetectors Photodiode Design Issues Photovoltaic Operation Photoconductive Operation Photodiode Small-Signal Model Integration Of Photodiodes With Standard Active Circuit Processes Ultraviolet-Optimized Photodiodes P-I-N Photodiodes Metal-Semiconductor (Schottky) Photodiodes Avalanche Photodiodes Phototransistors Photo-Darlington Transistors Solar Cells Anomalous Photovoltaic Effect 2.2.7 Capacitive Photosensors Charge-Coupled Image Sensors Mos-Capacitor Ultraviolet Sensors 2.3 Indirect Optical Sensors 2.3.1 Pyroelectric Detectors Electro-Sprayed PVDF Pyroelectric Sensor 2.3.2 Bolometers Uncooled Bolometers Superconducting Bolometers 2.3.3 Thermopiles 2.3.4 Golay Cells Micromachined Tunneling-Based Golay Cell Micromachined Capacitive Golay Cell 2.3.5 Phosphors And Other “Indirect” Light Sensors 2.3.6 Comparision Of Indirect Optical Microsensors 2.4 Biological Light Sensors 2.4.1 Structures Of Human Visual Transduction 2.4.2 Basic Visual Transduction Mechanism 3. Optical Actuators 3.1 Light Emitters 3.1.1 Light Emitting Diodes 3.1.2 Silicon Light Emitting Diodes 3.1.3 Organic Light Emitting Diodes 3.1.4 Gas And Solid-State Lasers Micromachined Solid-State Lasers 3.1.5 Micromachined Incandescent Lamps 3.1.6 Plasma Light Sources 3.1.7 Electroluminescent Light Sources 3.1.8 Field Emission Displays 3.1.9 Bioluminescence 3.2 Light Modulators 3.2.1 Liquid Crystal Displays Nematic Liquid Crystals Dynamic Scattering Liquid Crystals Transferred Silicon Active Lc Displays Cholesteric Liquid Crystals 3.2.2 Reflective Micromechanical Light Modulators Electrostatic Reflective Light Modulators Westing House Mirror Matrix Tube Silicon Cantilever Light Modulators Torsional Silicon Electrostatic Light Modulators Torsional Aluminum Electrostatic Light Modulators Polysilicon Torsional Optical Modulators Deformable Grating Light Modulators Electrostatic Membrane Light Modulator Magnetically Deflected Light Modulators Magnetic/Electrostatic Light Modulators 3.2.3 Transmissive Micromechanical Light Modulators 3.2.4 Other Light Modulators 4. Micromachined Optical Structures 4.1 Micromachined Fiber-Optic Couplers 4.2 Micromachined Reflective Components 4.2.1 Fixed Micromirrors 4.2.2 Positionable Micromirrors 4.3 Micromachined Transmissive Components 4.3.1 Optical Waveguides 4.3.2 Lenses Refractive Lenses Diffractive Gratings And Lenses 4.4 Filters And Spectrometers 4.4.1 Interference Filters 4.4.2 Fabry-Perot Filters 4.4.3 Mechanically Tunable IR Filters 4.4.4 Spectrometers Fabry-Perot Spectrometers Dispersive Spectrometers 4.5 Integrated Optical Systems 4.5.1 Integrated Free-Space Optical Systems Optical Transducers References Chapter 5: Ionizing Radiation Transducers 1. Introduction 1.1 Units Of Measure For Radiation 1.2 Types Of Radiation 1.2.1 Alpha Radiation 1.2.2 Beta Radiation 1.2.3 Gamma Radiation And X-Rays 1.2.4 Neutron Radiation 2. Ionization-Based Detectors 3. Scintillation Detectors 4. Direct Solid-State Radiation Detectors 4.1 Integrated Detector Arrays 5. Other Detector Types 5.1 Transmutation-Based Sensors 5.2 Cerenkov Effect Detectors 5.3 Thermal Detectors 5.4 Mos Threshold Voltage Shift Detectors 5.5 Thermoluminescent Detectors 5.6 Collimators 6. Radiation Effects On Electronics 7. Biological Interactions With Radiation Radiation Transducers References Chapter 6: Thermal Transducers 1. Introduction 2. Temperature Measurements 2.1 Basic Terms 2.2 Modes Of Heat Transfer 2.2.1 Conduction 2.2.2 Convection 2.2.3 Radiation 2.3 Non-Contact Temperature Measurements 2.4 Thermo-Mechanical Sensors 2.5 Thermoresistive Transducers 2.5.1 Thermoresistive Effects 2.5.2 Simple Thin-Film Thermoresistors 2.5.3 Thermistors 2.5.4 Semiconductor Thermoresistors/Thermistors 2.5.5 Self-Heating Effects In Resistive Sensors 2.5.6 Interface Circuits 2.6 Thermocouples 2.7 Junction-Based Thermal Sensors 2.7.1 Diode Temperature Sensors 2.7.2 Transistor Temperature Sensors Basic PTAT Circuit Switched PTAT Circuit Desensitizing Circuits To Temperature 2.8 Other Thermal Sensors 2.8.1 Acoustic Temperature Sensors 2.8.2 Quartz And Other Resonant Temperature Sensors 2.8.3 Tunneling Temperature Sensors 2.9 Biological Thermal Sensors 3. Thermal Actuators 3.1 Joule-Thompson Refrigerators 3.2 Other Fluidic Coolers 3.3 Peltier Effect Heat Pumps 4. Thermal Sensor/Actuator Combinations 4.1 Thermally Stabilized Circuits 4.2 Thermal AC/RMS Converters 5. Thermal Gas Pressure Sensors 6. Thermal Flow Sensors 7. Other Thermal Sensors 7.1 Micromachined Calorimeters 7.2 Dew-Point (Thermal) Humidity Sensors 7.3 Thermal Electromagnetic Mixers Thermal Transducers References Chapter 7: Magnetic & Electromagnetic Transducers 1. Introduction 1.1 Terms And Definitions 2. Magnetic Phenomena 2.1 The Hall Effect 2.1.1 Hall Effect In Semiconductors 2.2 Physical Magnetoresistive Effect 2.3 Geometric Magnetoresistive Effect 2.4 Giant Magnetoresistive Effect 2.5 Magneto-Optical Effects 2.6 Magnetic Anisotropy 2.6.1 Shape Anisotropy 2.6.2 Stress Anisotropy 2.6.3 Crystalline Anisotropy 2.7 Magnetic Domains 3. Magnetic Sensors 3.1 Hall Effect Sensors 3.1.1 Plate Design For Hall-Voltage Sensors 3.1.2 Offset Voltage Issues 3.1.3 Hall Plates In Bipolar Processes 3.1.4 Mos Hall Plates 3.1.5 Non-Silicon Hall Plate Materials 3.1.6 Magnetodiodes 3.1.7 Magnetotransistors 3.1.8 Split-Drain Magfets 3.1.9 Hall Devices In Integrated Circuits 3.2 Carrier Domain Magnetometers 3.3 Flux-Gate Magnetometers 3.4 Tunneling Magnetometers 3.5 Tunnel Diode Magnetic Sensors 3.6 Vacuum Electron Magnetic Sensors 3.7 Superconducting Quantum Interference Magnetometers 3.8 Other Magnetic Sensors 3.8.1 Wiegand Wires 3.9 Biological Magnetic Sensors 4. Magnetic Actuators 4.1 Magnetic Field Actuators 4.2 Magnetostrictive Actuators 4.3 Magnet Fabrication 4.4 Magnetic Actuators With Drive Coils 4.4.1 Electroplated Magnetic Coils 4.4.2 Wire-Bonded Magnetic Coils 4.4.3 Externally Wound Magnetic Coils 4.5 Magnetic Actuators Using External Fields 4.6 Magnetic Micromotors 4.7 Eddy-Current Defect Sensors 4.8 Resonant Magnetic Sensors 4.9 Magnetic Read/Write Heads 4.9.1 Magnetic Heads For Storage Devices Inductive Magnetic Heads Magnetoresistive Read Heads 4.9.2 Magnetic Ink Print Heads 4.10 Magnetic Bubble Memory 5. Micromachined Electromagnetic Devices 5.1 Passive Components And Circuits 5.2 Other RF Applications Of Micromachining Magnetic And Electromagnetic Transducers References Chapter 8: Chemical And Biological Transducers 1. Introduction 2. Chemical Sensors 2.1 Passive Chemical Sensors 2.1.1 Chemiresistors 2.1.2 Chemicapacitors 2.1.3 Chemomechanical Sensors 2.1.4 Calorimetric Sensors 2.1.5 Metal-Oxide Gas Sensors 2.2 Work-Function-Based Sensors 2.2.1 ADFET Gas Sensors 2.2.2 Platinide-Based Hydrogen Sensors 2.2.3 Ion-Sensitive FETs (ISFETs And CHEMFETs) 2.3 Electrochemical Transducers 2.3.1 Ionic Capacitance 2.3.2 Charge Transfer: Resistive Mechanisms 2.3.3 Spreading Resistance And Warburg Impedance 2.3.4 Basic Electrode Circuit Model 2.3.5 Electrochemical Sensing Using Microelectrodes Potentiometric Sensing Amperometric Sensing Other Electrochemical Sensing Methods 2.4 Acoustic Wave Sensors 2.5 Biosensors 2.5.1 Resonant Biosensors 2.5.2 Optical-Detection Biosensors 2.5.3 Thermal-Detection Biosensors 2.5.4 Isfet Biosensors (Chemfets) 2.5.5 Other pH-Based Biosensors 2.5.6 Electrochemical-Detection Biosensors 2.5.7 CMOS-Compatible Biosensor Process 2.5.8 Other Biosensor Technologies 2.6 Biomolecular Gain Mechanisms 2.7 Selectivity Improvement Using Arrays 2.8 Combinatorial Arrays 2.9 Biological Chemical Sensors 2.9.1 Biological "Taste" Sensors 2.9.2 Biological Odor Sensors 3. Chemical Actuators 3.1 Electrochemical Mechanical Actuators 3.2 Polymer Mechanical Actuators 3.3 Thin-Film Batteries 4. Bioelectric Interface Devices 4.1 Penetrating Neural Probes 4.2 Regeneration Neural Electrodes 4.3 Cultured Cell Systems 4.3.1 Surface Modification For Culture Systems 5. Hybrid Biosensors Chemical And Biological Transducers References Chapter 9: Microfluidic Devices 1. Introduction 1.1 Basic Fluid Properties And Equations 1.2 Types Of Flow 1.3 Bubbles And Particles In Microstructures 1.4 Capillary Forces 1.5 Fluidic Resistance 1.6 Fluidic Capacitance 1.7 Fluidic Inductance 2. Flow Channels 2.1 Bulk Micromachined Channels 2.2 Surface Micromachined Channels 2.3 Other Channel Types And System Approaches 3. Fluidic Channel Applications 3.1 Mixers 3.1.1 Laminating Mixers 3.1.2 Plume Mixers 3.1.3 Active Mixers 3.2 Diffusion-Based Extractors 3.3 Fluidic Amplifiers And Logic 4. Fluidic Sensors 4.1 Flow Sensors 4.2 Viscosity/Density Sensors 4.3 Other Fluidic Sensors 5. Valves 5.1 Passive Valves 5.2 Active Valves 5.2.1 Pneumatic Valve Actuation 5.2.2 Thermopneumatic Valve Actuation 5.2.3 Phase-Change Valve Actuation 5.2.4 Solid-Expansion Thermal Valve Actuation 5.2.5 Piezoelectric Valve Actuation 5.2.6 Electrostatic Valve Actuation 5.2.7 Electromagnetic Valve Actuation 5.2.8 Bistable Valve Structures 6. Pumps 6.1 Bubble Pumps 6.2 Membrane Pumps 6.3 Diffuser Pumps 6.4 Rotary Pumps 6.5 Electrohydrodynamic Pumps 6.5.1 Injection-Type EHD Pumps 6.5.2 Non-Injection-Type EHD Pumps 6.6 Electroosmotic/Electrophoretic Pumps 6.7 Ultrasonic Pumps 6.8 Vacuum Pumps 7. Droplet Generators 8. Other Devices 8.1 Control Of Macroscopic Flows With Microdevices 8.2 Particle Filters And Traps 9. Microfluidic System Issues 9.1 Interconnects 9.2 Packaging/System Integration 9.3 Design For Disposal Or Reuse 10. Integrated Chemical Analysis Systems 10.1 Scaling Issues For Chemical Analysis 10.2 Gas Chromatography Systems 10.3 Liquid Chromatography Systems 10.4 Electrophoresis Systems 10.5 Cell Fusion Devices 10.6 DNA Amplification (PCR) Systems 10.7 Multifunctional Fluidic Systems 11. Biological Fluidic Systems 11.1 Biological Flow Channels 11.2 Biological Valves 11.2.1 Passive Biological Valves 11.2.2 Active Biological Valves 11.3 Biological Pumps Microfluidic Devices References Index Epilogue