P REFACE TO V OLUME 1: G ENERAL A PPROACHES This volume provides an introduction to the fundamentals of sensing materials. We have tried to to provide here the basic knowledge necessary for understanding chemical sensing through a brief de- scription of the principles of chemical sensor operation and consideration of the processes that take place in chemical sensors and that are responsible for observed operating characteristics. In spite of the seeming extreme simplicity of chemical sensor operation and application, understanding the mecha- nisms involved in the process of chemical sensing is usually not so simple. Chemical sensing as a rule is a multistage and multichannel process, which requires a multidisciplinary approach. Therefore, in this volume we provide a description of the important electronic, electrophysical, and chemical properties, as well as diffusion, adsorption/desorption, and catalytic processes. To our knowledge, this volume is the first attempt to analyze in detail the interrelationships be- tween properties of sensing materials and operating parameters of chemical sensors. This volume describes the properties of sensing materials by emphasizing the specificities of these materials. We consider analyses that have been performed as bridging the gap between scientists studying properties of materials and researchers using these materials for actual chemical sensor design. We hope that the information included in this volume will help readers to approach soundly the selection of either sens- ing materials or technology for sensing material synthesis or deposition. Detailed consideration of various materials properties with respect to their application in chemical sensors provides a clear idea of the complexity and ambiguity involved in selecting an optimal sensor material. Research has demonstrated that there is no universal sensing material, and selection of an optimal material is determined by the type of chemical sensor being designed and the requirements that device will have to meet. This volume also illustrates the complementary nature of functionality in sens- ing materials; for example, high sensitivity usually conflicts with stability. This richness and complexity in behavior cannot be ignored. This volume is intended to provide readers with a good understanding of the techniques used for synthesis and deposition of sensing materials. Readers will find descriptions of different tech- niques such as various methods of film deposition, sol-gel technology, deposition from solutions, col- loidal processing, the peculiarities of polymers synthesis, techniques used for depositing coatings on fibers, and so on. Description of various methods of synthesis and deposition, accompanied by detailed xiii