This book presents an overview of up-converting phosphor (UCP), including UCP preparation, development of the rapid detection strips and UCP industrialization. It also discusses the wide clinical applications of this technology, such as in food poisoning, infectious diseases, drug-abuse and disaster rescue, where rapid point-of-care testing is often critical. Conventional testing methods are mainly based on gold immunochromatography, which relies heavily on results being read with the naked eye. However, up-converting phosphor technology (UPT) employs UCP particles as labels for rapid target detection. Unlike other conventional fluorescence techniques, UCP is excited by infrared light and emitted visible light. This anti-stokes phenomenon provides this special label with significant advantages, including zero background detection, high resistance to environmental influences (e.g. pH, salts, sample contamination), high sensitivity and quantitative detection. Systematically summarizing UCP technology and its wide applications, this book is a valuable resource for researchers and technicians in the field.