Monitoring emissions is a chief concern for many industries, especially those such as the automobile industry where restrictions are tightening each year. Zirconia-based sensors are widely used when specificity, accuracy, and reliability are of paramount concern. This book is the first to present a detailed analysis of the electrochemistry, development, modeling, optimization, and technology behind modern zirconia-based sensors as well as tailoring these sensors to meet specific industrial needs. The author pays particular attention to the factors that determine high sensitivity, critically reviews the limitations of current technologies, and surveys the needs and possibilities of future developments.