Nanomaterials and nanoscale interactions span an important and wide-ranging sector of modern science and industry. Championing developments in these fields, SPIE stages an annual forum to stimulate and support their growth: the Nanoscience and Engineering Symposium. This book represents a selection of compelling contributions from some of those innovators closely involved since the launch of this symposium. Among the key advances included are accomplishments with nanowaveguides, silicon photonics, solar energy conversion, lighting, nanofabrication and structure-determining methods for polymeric, organic, inorganic and composite materials, as well as biomaterials that can frequently achieve first-class response characteristics and that are of low-cost, and are readily available and environmentally responsible. Together, these contributions give a fascinating portrayal of the state of the art in the shifting landscape of current nanoscience and engineering.
The world of nanomaterials and the study of nanoscale interactions span a hugely important and wide-ranging sector of modern science and industry. It is easy to forget how rapidly their prominence has grown since the turn of this century, when nanoscience and nanotechnology were still essentially in their infancy. At that time, the propagation of some fantastically inflated speculation—and considerable scaremongering in some quarters—had become sufficiently rife that anything with a ‘nano’ prefix was in danger of being regarded either as pure hype, or as something associated with irresponsibly high risk. Yet those most closely involved saw the true potential, recognizing the need for safeguards and for investment to support advances that could hold genuinely transformative potential.
As key decision makers in increasing numbers became persuaded of the solidity and promise of the subject, the next few years saw a spate of Institute of Nanoscience foundations, such as those in Pittsburgh in 2002, NRL (U.S. Naval Research Laboratory) in 2003, Delft in 2004, and both Iowa City and Basel in 2006. At around the same time, the increasing number of presentations on ‘nano’ topics began to draw the attention of conference organizers and managers, leading to new streams of conference material. With customary vision, SPIE led the forefront of developments with an aim to provide a central forum for such topics and to stimulate and support their growth. Starting with a workshop on nanomaterials in 2002, the structuring of conferences at its annual summer meeting (most often in San Diego) was purposefully focused and extended into a cohesive stream of content that emerged into its now familiar form, the Nanoscience and Engineering Symposium.
It is a pleasure and honor to have been involved in this symposium since the outset, alongside my friend and colleague Jim Grote. It has been our great delight to witness the growth in size and reputation of the symposium and to find so many internationally eminent individuals—more than sixty since the inception in 2002—prepared to come and deliver plenary lectures. The present monograph represents a careful selection of chapters from some of those most closely involved; their contributions aim to bring the reader up to date with the numerous advances that continue to shape and reshape the subject. In this International Year of Light, it is particularly appropriate that a large number of these advances relate to optical materials, interactions, or measurements. Indeed, the prominence of light-related topics in the whole sphere of nanoscience research and development befits the positioning of the Nanoscience and Engineering Symposium within SPIE’s Optics and Photonics event. Yet, the subject matter extends well beyond the boundaries of nanophotonics and nano-optics, and its true interdisciplinarity will be more than evident in the pages that follow.
In Chapter 1, He et al. describe how advanced methods of nanofabrication now enable the construction of nanowaveguides whose performance can be enhanced by harnessing plasmonic interactions, or, for example, by the incorporation of graphene elements. Such devices provide a basis for a variety of emerging applications in polarizers, optical communications, high-sensitivity, real-time biosensing, and light harvesting. Pavesi et al., in Chapter 2, also discuss engineered nanostructures, here with a focus on silicon photonics. This is a growth area in its own right, since silicon offers scope to reduce the massive power demands of major communications routers such as those engaged in Internet search engines. Although the prospect of a relative ease of integration with existing semiconductor fabrication methods is attractive, true integration is limited by the complexity of integrated photonic circuits. This chapter shows how some of the outstanding problems can be circumvented or mitigated. Silicon microresonators have significant applications in biosensing and in optomechanics.
Chapter 3 by Lee et al. concerns an important area of application for nonlinear optics, in which two-photon-induced polymerization or allied lithography methods are deployed in the 3D microfabrication of polymeric, organic, and inorganic materials. The full capability of such an approach can be gauged by its capacity to create complex regular structures such as photonic crystals, using a photoresist incorporating a dye with a large twophoton- absorption cross section. The same technique can be adapted for the nanofabrication of atomic force microscopy tips, or components in microfluidic motors. Campo et al., in Chapter 4, then describe the use of structure-determining methods such as near-edge x-ray absorption fine structure (NEXAFS) or Raman spectroscopy to achieve a better understanding of the noncovalent interactions that determine the bulk physical properties of many novel polymeric composites. Here, particular interest is in composites incorporating carbon nanotubes, which can lead to dramatic improvements in mechanical, thermal, electrical, and optical properties. Such composites hold promise for commercial applications that include textiles, fuselage constructs, and haptic screens.
In Chapter 5, Monti and Armaroli discuss the principles of molecular engineering for solar energy conversion and new materials for lighting—areas linked by a common dependence on electron- and energy-transfer pathways, typically involving molecular complexes and fullerenes as well as transitionmetal ions. With the global drive toward lower energy consumption and a reduced dependence on fossil fuels, these materials are helping to address the continuing need to develop higher efficiency and better quality lighting. Chapter 6, by Sullivan and Dalton, then takes a comprehensive look at theory-guided principles for the design of organic electro-optical materials and silicon/plasmonic–organic hybrids. Recent advances in this area provide the means to engineer for improved control of material viscoelasticity, reductions in optical loss, and increases in both thermal and photochemical stability.
The subject of the subsequent three chapters is biomaterials and biopolymers. This is another area of significant recent development, in which the often astonishingly propitious physical properties of natural biological materials are exploited in new products. Chapter 7 by Grote et al. deals with photonic applications, and Chapter 8, also by Grote et al., covers electronic applications, showing that many of the most promising new materials are formed as films or composites from DNA biopolymers. Such polymers have optical properties that are often comparable in performance or, in many cases, superior to traditional polymers. Moreover, they prove to be especially robust against UV or gamma radiation and are therefore materials potentially suitable for future space-based applications. Yet another class of biomaterials discussed by Melucci and Zamboni in the concluding Chapter 9 are those based on silk fibroin, sustainably fabricated by reverse engineering from silkworm cocoons. Here, composites with functional organic compounds provide the basis for a wide range of tailored materials with exciting new properties, suited for the manufacture of multifunctional bioactive devices.
I commend this volume to its readers as an indication of the breadth and scale of recent advances in nanoscience. And in conclusion, I offer sincere thanks to all contributors for delivering manuscripts of such high quality, comprehensively covering such a wide a range of topics, and to the invariably helpful and professional staff of SPIE’s publishing division, who have strongly supported this project from the start and have brought it to a timely fruition.
David L. Andrews