Book excerpt: The need for new types of sensors is more critical than ever. This is due to the emergence of increasingly complex technologies, health and security concerns of a burgeoning world population, and the emergence of terrorist activities, among other factors. Depending on their application, the design, fabrication, testing, and use of sensors, all require various kinds of both technical and nontechnical expertise. With this in mind, Introduction to Sensors examines the theoretical foundations and practical applications of electrochemical, piezoelectric, fiber optic, thermal, and magnetic sensors and their use in the modern era. Incorporating information from sensor-based industries to review current developments in the field, this book: Presents a complete sensor system that includes the preparation phase, the sensing element and platform, and appropriate electronics resulting in a digital readout Discusses solid-state electronic sensors, such as the metal oxide semiconductor (MOS) capacitor, the micromachined capacitive polymer, and the Schottky diode sensors Uses the two-dimensional hexagonal lattice as an example to detail the basic theory associated with piezoelectricity Explores the fundamental relationship between stress, strain, electric field, and electric displacement The magnetic sensors presented are used to determine measurands such as the magnetic field and semiconductor properties, including carrier concentration and mobility. Offering the human body and the automobile as examples of entities that rely on a multiplicity of sensors, the authors address the application of various types of sensors, as well as the theory and background information associated with their development and the materials used in their design. The coverage in this book reveals the underlying rationale for the application of different sensors while also defining the properties and characteristics of each.