Multiphoton Lithography: Techniques, Materials, and Applications

This first book on this fascinating, interdisciplinary topic meets the much-felt need for an up-to-date overview of the field. Written with both beginners and professionals in mind, this ready reference begins with an introductory section explaining the basics of the various multi-photon and photochemical processes together with a description of the equipment needed. A team of leading international experts provides the latest research results on such materials as new photoinitiators, hybrid photopolymers, and metallic carbon nanotube composites. They also cover promising applications and prospective trends, including photonic crystals, microfluidic devices, biological scaffolds, metamaterials, waveguides, and functionalized hydrogels. By bringing together the essentials for both industrial and academic researchers, this is an invaluable companion for materials scientists, polymer chemists, surface chemists, surface physicists, biophysicists, and medical scientists working with 3D micro- and nanostructures.

Table of Contents:
List of Contributors XI Foreword XVII Introduction XIX Part I Principles of Multiphoton Absorption 1 1 Rapid Laser Optical Printing in 3D at a Nanoscale 3 Albertas Žukauskas, Mangirdas Malinauskas, Gediminas Seniutinas, and Saulius Juodkazis 1.1 Introduction 3 1.2 3D (Nano)polymerization: Linear Properties 4 1.2.1 Photocure andThermal Cure of Photoresists 5 1.2.2 Tight Light Focusing 6 1.2.3 Optical Properties at High Excitation: From Solid to Plasma 8 1.2.4 Heat Accumulation 10 1.3 3D (Nano)polymerization: Nonlinear Properties 13 1.3.1 Strongest Optical Nonlinearities 13 1.3.2 Avalanche Versus Multiphoton Excitation 15 1.4 Discussion 17 1.5 Conclusions and Outlook 18 Acknowledgments 19 References 19 2 Characterization of 2PA Chromophores 25 EricW. Van Stryland and David J. Hagan 2.1 Introduction 25 2.2 Description of Nonlinear Absorption and Refraction Processes 26 2.2.1 Two-Photon Absorption and Bound-Electronic Nonlinear Refraction 26 2.2.2 Excited-State Absorption and Refraction 28 2.3 Methods for Measurements of NLA and NLR 31 2.3.1 Direct Methods 31 2.3.1.1 Nonlinear Transmission 31 2.3.1.2 Z-Scan 32 2.3.1.3 Determining Nonlinear Response from Pulse-width Dependence of Z-Scans 39 2.3.1.4 White-Light-Continuum Z-Scan (WLC Z-Scan) 41 2.3.1.5 Other Variants of the Z-Scan Method 43 2.3.2 Indirect Methods 45 2.3.2.1 Excitation–Probe Methods 45 2.3.2.2 White-Light-Continuum (WLC) Excite–Probe Spectroscopy 48 2.3.2.3 Degenerate Four-Wave Mixing (DFWM) 51 2.3.2.4 Two-Photon-Absorption-Induced Fluorescence Spectroscopy 53 2.3.2.5 Fluorescence Anisotropy 55 2.4 Examples of Use of Multiple Techniques 55 2.4.1 Squaraine Dye 56 2.4.2 Tetraone Dye 57 2.5 Other Methods 59 2.6 Conclusion 60 Acknowledgments 60 References 60 3 Modeling of Polymerization Processes 65 Alexander Pikulin and Nikita Bityurin 3.1 Introduction 65 3.2 Basic Laser Polymerization Chemistry and Kinetic Equations 66 3.3 Phenomenological PolymerizationThreshold and Spatial Resolution 69 3.4 Effect of Fluctuations on the Minimum Feature Size 75 3.5 Diffusion of Molecules 83 3.5.1 Diffusion of the Growing Chains 84 3.5.2 Diffusion of Inhibitor: Diffusion-Assisted Direct LaserWriting 86 3.6 Conclusion 90 Acknowledgements 91 References 91 Part II Equipment and Techniques 95 4 Light Sources and Systems for Multiphoton Lithography 97 Ulf Hinze and Boris Chichkov 4.1 Laser Light Sources 97 4.2 Ultrashort-Pulse Lasers 98 4.3 Laboratory Systems and Processing Strategy 100 4.4 Further Processing Considerations 105 References 108 5 STED-Inspired Approaches to Resolution Enhancement 111 John T. Fourkas 5.1 Introduction 111 5.2 Stimulated Emission Depletion Fluorescence Microscopy 113 5.3 Stimulated Emission Depletion in Multiphoton Lithography 117 5.4 Photoinhibition 122 5.5 Inhibition Based on Photoinduced Electron Transfer 123 5.6 Absorbance Modulation Lithography 126 5.7 Challenges for Two-Color, Two-Photon Lithography 127 5.8 Conclusions 128 Acknowledgments 128 References 128 Part III Materials 133 6 Photoinitiators for Multiphoton Absorption Lithography 135 Mei-Ling Zheng and Xuan-Ming Duan 6.1 Introduction for Photoinitiators for Multiphoton Absorption Lithography 135 6.1.1 Multiphoton Absorption Lithography 135 6.1.2 Photoinitiators for Multiphoton Absorption Lithography 135 6.1.2.1 History of the Design of Two-Photon Initiators 135 6.1.2.2 Property of Two-Photon Initiators 136 6.1.3 Characterization of Two-Photon Initiators 137 6.1.4 Molecular Design for Photoinitiators 140 6.2 Centrosymmetric Photoinitiators 141 6.3 Noncentrosymmetric Photoinitiators 153 6.4 Application of Photoinitiators in Multiphoton Absorption Lithography 156 6.5 Conclusion 162 Acknowledgment 163 References 163 7 Hybrid Materials for Multiphoton Polymerization 167 Alexandros Selimis and Maria Farsari 7.1 Introduction 167 7.2 Sol–Gel Preparation 168 7.3 Silicate Hybrid Materials 169 7.4 Composite Hybrid Materials 171 7.5 Surface and Bulk Functionalization 173 7.6 Replication 175 7.7 Conclusions 176 References 176 8 Photopolymers for Multiphoton Lithography in Biomaterials and Hydrogels 183 Mark W. Tibbitt, Jared A. Shadish, and Cole A. DeForest 8.1 Introduction 183 8.2 Multiphoton Lithography (MPL) for Photopolymerization 186 8.3 MPL Equipment for Biomaterial Fabrication 188 8.4 Chemistry for MPL Photopolymerizations 189 8.4.1 Photopolymerization 189 8.4.2 Photoinitiator Selection 191 8.4.3 Photopolymer Chemistries 193 8.4.3.1 Macromer Chemistries 193 8.4.3.2 Photochemical Polymerization and Degradation 194 8.5 Biomaterial Fabrication 202 8.6 Biomaterial Modulation 203 8.7 Biological Design Constraints 206 8.8 Biologic Questions 208 8.9 Outlook 209 References 210 9 Multiphoton Processing of Composite Materials and Functionalization of 3D Structures 221 Casey M. Schwarz, Christopher N. Grabill, Jennefir L. Digaum, Henry E.Williams, and Stephen M. Kuebler 9.1 Overview 221 9.2 Polymer–Organic Composites 225 9.2.1 Fluorescent-Dye-Doped Organic Microstructures 225 9.2.2 Organic Composites for Lasing Microstructures 227 9.2.3 Organic Composites for Electrically Conductive Microstructures 227 9.2.4 Other Optically Active Microstructures 229 9.3 Multiphoton Processing of Oxide-Based Materials 230 9.3.1 Titanium Dioxide 231 9.3.2 Zinc Oxide 231 9.3.3 Zirconium Dioxide 232 9.3.4 Iron Oxide 232 9.3.5 Tin Dioxide 233 9.3.6 Germanium Dioxide 234 9.3.7 Silicon Dioxide 234 9.4 Multiphoton Processing of Metallic Composites and Materials 235 9.4.1 Thermal Evaporation 236 9.4.2 e-Beam Evaporation 236 9.4.3 Magnetron Sputtering 236 9.4.4 Chemical Vapor Deposition 237 9.4.5 Functionalization by Attachment of Nanoparticles 238 9.4.6 Electroless Metallization from Solution 239 9.4.7 Multiphoton Lithography of Nanoparticles Supported in a Polymer Matrix 242 9.4.8 DirectWriting of Continuous-Metal Microstructures 244 9.4.9 Metal Backfilling by Electroplating 245 9.5 Multiphoton Processing of Semiconductor Composites and Materials 246 9.5.1 Structures Functionalized with Nanoparticles 246 9.5.2 Structures Functionalized using NP–Polymer Composites 246 9.5.3 Structures Functionalized by In Situ NP Formation 247 9.5.4 Structures Functionalized by NP Coating 248 9.5.5 Structures Functionalized by Silicon Inversion 250 9.5.6 Functional Structures Fabricated in Bulk Chalcogenide Glasses 252 9.5.7 Structures Fabricated in ChG Film 252 9.5.8 Structures Fabricated in ChG–NP Composites 254 9.6 Conclusion 254 Acknowledgments 255 References 255 Part IV Applications 265 10 Fabrication ofWaveguides and Other Optical Elements by Multiphoton Lithography 267 Samuel Clark Ligon, Josef Kumpfmüller, Niklas Pucher, Jürgen Stampfl, and Robert Liska 10.1 Introduction 267 10.2 Acrylate Monomers for Multiphoton Lithography 268 10.3 Thiol–Ene Resins 277 10.4 Sol–Gel-Derived Resins 280 10.5 Cationic Polymerization and Stereolithography 284 10.6 Materials Based on Multiphoton Photochromism 287 10.7 Conclusions 292 Acknowledgments 292 References 292 11 Fabricating Nano and Microstructures Made by Narrow Bandgap Semiconductors and Metals using Multiphoton Lithography 297 Min Gu, Zongsong Gan, and Yaoyu Cao 11.1 Introduction 297 11.2 Fabrication of 3D Structures Made by PbSe with Multiphoton Lithography 298 11.2.1 Challenges of Multiphoton Lithography with Top-Down Approach for Narrow Electronic Bandgap Semiconductors 298 11.2.2 Photoresin Development 299 11.2.3 Two-Photon Lithography of PbSe Structures 302 11.2.4 Confirmation of PbSe Formation 303 11.3 Fabrication of Silver Structures with Multiphoton Lithography 304 11.3.1 Principle of Resolution Improvement by Increasing Photosensitivity in Photoreduction 305 11.3.2 Photosensitivity Enhancement by Tuning LaserWavelength 305 11.3.3 Dot Size Model Based on Photosensitivity 308 11.3.4 Further Increase the Photosensitivity with an Electron Donor 310 11.4 Conclusions 310 Acknowledgments 312 References 312 12 Microfluidic Devices Produced by Two-Photon-Induced Polymerization 315 Shoji Maruo 12.1 Introduction 315 12.2 Fabrication of Movable Micromachines 316 12.3 Optically Driven Micromachines 320 12.4 Microfluidic Devices Driven by a Scanning Laser Beam 325 12.5 Microfluidic Devices Driven by a Focused Laser Beam 327 12.6 Microfluidic Devices Driven by an Optical Vortex 330 12.7 Future Prospects 331 References 332 13 Nanoreplication Printing and Nanosurface Processing 335 Christopher N. LaFratta 13.1 Introduction: Limitations of Multiphoton Lithography 335 13.2 Micro-transfer Molding (μTM) 336 13.3 μTM of Complex Geometries 338 13.4 Nano-replication of Other Materials 339 13.5 Nanosurface Metallization Processing 342 13.6 Nanosurface Structuring via Ablation 344 13.7 Conclusion and Future Directions 349 References 351 Part V Biological Applications 353 14 Three-Dimensional Microstructures for Biological Applications 355 Adriano J. G. Otuka, Vinicius Tribuzi, Daniel S. Correa, and Cleber R. Mendonça 14.1 Introduction 355 14.2 3D Structures for Cells Studies 357 14.3 Biocompatible Materials 363 14.4 Scaffolds for Bacterial Investigation 368 14.5 Microstructures for Drug Delivery 371 14.6 Final Remarks 374 References 374 Index 377

About the Author :
Jurgen Stampfl studied Applied Physics at the University of Technology in Graz (Austria) and received his PhD in Materials Science from the University of Leoben (Austria) in 1996. From 1997 to 2000, he worked as a research associate at the Rapid Prototyping Lab at Stanford University (USA). In 2001, he joined the Institute of Materials Science and Technology at the Vienna University of Technology (Austria), where he was appointed associate professor for Materials Science in 2005. He is head of the working group Functional Non-Metals and since 2012 (together with Robert Liska) head of the Christian Doppler Laboratory for photopolymers in digital and restorative dentistry. His expertise lies in the field of additive manufacturing technologies and the development and characterization of advanced materials. Robert Liska received his PhD from the Vienna University of Technology (Austria) in 1998. In 2006, he completed his habilitation with a work on the topic of macromolecular chemistry. He is leader of the research group Photopolymerization at the Institute of Applied Synthetic Chemistry at the Vienna University of Technology. In 2012, he became head of the Christian Doppler Laboratory for photopolymers in digital and restorative dentistry and since 2016 he is full professor for organic technology. He is interested in the research topics photoinitiation, photopolymerization, additive manufacturing, and biomedical polymers. Liska is co-author of eight book chapters and of more than 100 peer-reviewed journal articles. Dr. Aleksandr Ovsianikov is currently an Assistant Professor at Vienna University of Technology (TU Wien, Austria). His research is dealing with the use of additive manufacturing technologies for tissue engineering and regeneration. Dr. Ovsianikov has background in laser physics and material processing with femtosecond lasers. After undergraduate studies at the Vilnius University (Lithuania) he completed his PhD at the Nanotechnology Department of the Laser Zentrum Hannover, and received his degree from the University of Hannover (Germany) in 2008. A particular focus of the current research of Dr. Ovsianikov is the development of multiphoton processing technologies for engineering biomimetic 3D cell culture matrices. In 2012 he was awarded a prestigious Starting Grant from the European Research Council (ERC) for a project aimed at this topic. Since 2004 Dr. Ovsianikov has contributed to over 60 publications in peer-reviewed journals and 5 book chapters.