With a strong foundation in material science and electronic engineering, this book describes the fundamentals and principles in the field of energy harvesting. Using a systems approach from overall system design down to device and component level, it provides the necessary theory and information to develop energy harvesting power supplies. The book explains overall system design and quantitative assumptions on environmental energy. Each block composing an energy harvesting power supply is analyzed and the book discusses trade-offs related to the design of the required buildings. The contributors cover different energy transducer technologies such as piezo-electric, electro-dynamic, solar-cells, and thermo-electric generators.