Microfabrication for Microfluidics

by Sang-Joon John Lee, Narayan Sundararajan

Overview

Providing a definitive source of knowledge about the principles, materials, and process techniques used in the fabrication of microfluidic systems and devices, this practical volume is an essential reference for novices and practicing professionals in the field. This unique book not only focuses on the fabrication aspects, but also covers the basic purpose, benefits, and limitations of the fabricated structures as they are applied to microfluidic sensor and actuator functions. Practitioners find guidance on rapidly assessing options and trade-offs for the selection of fabrication methods with several tabulated examples from the field. More than 100 illustrations support and clarify key concepts throughout the book.

Product Details

ISBN-13:	9781596934719
Publisher:	Artech House, Incorporated
Publication date:	04/30/2010
Pages:	280
Product dimensions:	6.10(w) x 9.20(h) x 0.80(d)

About the Author

Sang-Joon John Lee is an assistant professor in the Department of Mechanical and Aerospace Engineering at San Jose Univeristy. He holds an M.S. and a Ph.D. in mechanical engineering from the Massachusetts Institute of Technology. Narayan Sundararajan is the chief technology officer at the Intel-Grameen joint venture at Intel Corporation. His prior experience includes various new business initiatives in bio-medical and life sciences, including new platform concepts for remote healthcare solutions. He received his Ph.D. from Cornell University.

Table of Contents

Preface xi

1 Introduction 1

1.1 A Fabrication Perspective 3

1.2 Scaling Laws and Fluid Phenomena 5

1.2.1 Viscous Flow 7

1.2.2 Surface Tension 9

1.2.3 Diffusion 10

1.3 Microfluidic Functions 11

1.3.1 Flow Control 12

1.3.2 Particle Manipulation 12

1.3.3 Fluid Ejection 13

1.4 Semantics 13

1.5 Categorizing Fabrication Processes 15

1.5.1 Bulk Micromachining Versus Surface Micromachining 15

1.5.2 Serial Versus Parallel Fabrication Processes 16

1.5.3 Major Fabrication Process Categories 16

1.6 Organization of this Book 17

References 19

2 Geometric Features 25

2.1 Common Types of Features 28

2.1.1 Cavities and Orifices 28

2.1.2 Microchannels 30

2.1.3 Membranes 34

2.2 Geometric Characteristics 36

2.2.1 Profile 36

2.2.2 Feature Resolution 40

2.2.3 Aspect Ratio 41

2.2.4 Degrees of Freedom 41

2.2.5 Surface Roughness 47

References 50

3 Materials for Microfluidic Devices 55

3.1 Types of Materials 56

3.1.1 Polymers 56

3.1.2 Silicon 59

3.1.3 Glass 61

3.1.4 Metals 62

3.1.5 Other Materials 63

3.2 Material Properties 64

3.2.1 Mechanical Properties 65

3.2.2 Thermal Properties 69

3.2.3 Electrical Properties 73

3.2.4 Optical Properties 77

3.2.5 Magnetic Properties 79

3.2.6 Other Physical Properties and Characteristics 80

3.2.7 Chemical Resistance 82

3.3 Surface Conditions 83

References 87

4 Photolithography 99

4.1 Introduction 99

4.1.1 Photoresist 100

4.1.2 Photomasks 100

4.2 Process Basics 101

4.2.1 Coating 102

4.2.2 Baking 103

4.2.3 Alignment 103

4.2.4 Exposure 105

4.2.5 Developing 108

References 108

5 Solidification Processes and Soft Lithography 111

5.1 Radiation-Selective Polymerization 112

5.1.1 Ultraviolet Polymerization 113

5.1.2 Alternative Radiation Sources 114

5.1.3 Multilevel Features and 3D Profiles 115

5.2 Casting and Molding 122

5.2.1 Primary Casting 124

5.2.2 Replica Molding 126

5.2.3 Microinjection Molding 128

5.2.4 Compression Molding 129

5.3 Thermoplastic Reshaping 129

5.3.1 Hot Embossing 130

5.3.2 Nanoimprint Lithography 131

5.3.3 Thermoforming 132

5.4 Tabulated Examples of Solidification Processes 132

References 134

6 Subtractive Processes 141

6.1 Wet Etching 144

6.1.1 Isotropic Wet Etching 145

6.1.2 Anisotropic Wet Etching 147

6.2 Dry Etching 150

6.2.1 Ion Etching 152

6.2.2 Vapor Phase Etching 153

6.2.3 Reactive Ion Etching 154

6.2.4 Deep Reactive Ion Etching 157

6.3 Directed Beam Subtractive Processes 158

6.3.1 Laser Ablation 159

6.3.2 Focused Ion Beam Milling 161

6.4 Mechanical Subtractive Processes 161

6.4.1 Precision Machining 162

6.4.2 Abrasive Jet Milling 162

6.4.3 Chemical-Mechanical Polishing 163

6.5 Tabulated Examples of Subtractive Processes 164

References 166

7 Additive Processes 173

7.1 Physical Vapor Deposition 175

7.1.1 Evaporation 178

7.1.2 Sputtering 178

7.1.3 Pulsed Laser Deposition 179

7.2 Oxidation 179

7.3 Chemical Vapor Deposition 180

7.4 Electroplating 183

7.5 Printing and Coating Techniques 186

7.5.1 Spin-on-Glass 187

7.5.2 Screen Printing and Blade Leveling 188

7.5.3 Micro Contact Printing 188

7.5.4 Ink-Jet Printing and Direct-Write Material Deposition 189

7.5.5 Dip-Pen Nanolithography 190

7.6 Tabulated Examples of Additive Processes 192

References 193

8 Fugitive and Sacrificial Release Processes 199

8.1 Reasons for Fugitive and Sacrificial Release Processes 201

8.2 Approaches to Fugitive and Sacrificial Release Processes 201

8.2.1 Examples of Approaches to Fugitive Processes 202

8.2.2 Examples of Approaches to Sacrificial Release Processes 206

8.3 Tabulated Examples of Fugitive and Sacrificial Release Processes 209

References 210

9 Substrate Bonding and Fluidic Interfacing 213

9.1 Reasons for Substrate Bonding 213

9.2 Process Issues and Selection Criteria for Substrate Bonding 214

9.3 Approaches to Substrate Bonding 216

9.3.1 Polymer Substrate Bonding 217

9.3.2 Glass Substrate Bonding 219

9.3.3 Silicon Substrate Bonding 220

9.3.4 Other Substrate Materials and Bonding Methods 221

9.4 Tabulated Examples of Bonding Processes 222

9.5 Practical Issues and Selection Criteria for Fluidic Interfacing 223

9.6 Approaches to Fluidic Interfacing 226

References 230

10 Functional Domains and System Integration 237

10.1 Perspectives on Microfluidic Functionality 237

10.2 Energy Transduction 239

10.2.1 Electrokinetic Transduction and Electrical Measurements 240

10.2.2 Electromechanical, Electromagnetic, and Electroacoustic Transduction 241

10.2.3 Electrothermal, Thermopneumatic, and Thermomechanical Transduction 241

10.2.4 Electrochemical and Chemomechanical Transduction 242

10.2.5 Optical Interfacing 243

10.2.6 Biological Interfacing 244

10.3 Microfluidic System Integration 244

References 246

List of Acronyms and Abbreviations 253

About the Authors 257

Index 259