The objective of this book is to provide a comprehensive overview on current research advancements in the design of efficient small scale energy harvesters through the contributions of internationally known researchers. The book covers a broad range of topics from the physics of energy conversion, the elaboration of electroactive materials and their technique, to the conception of a complete micro generator based on its input energy source. It will help readers in their research and provide them with new ideas in the vast area of energy harvesting.