Significant progress has been made in recent years in quenched-phosphorescence oxygen sensing, particularly in the materials and applications of this detection technology that are open to commercialization, like uses in brain imaging and food packaging. Prompted by this, the editors have delivered a dedicated book that brings together these developments, provides a comprehensive overview of the different detection methodologies, and representative examples and applications. This book is intended to attract new researchers from various disciplines such as chemistry, physics, biology and medicine, stimulate further progress in the field and assist in developing new applications. Providing a concise summary at the cutting edge, this practical guide for current experts and new potential users will increase awareness of this versatile sensing technology.