Roundy (University of California-Berkeley) reports on a research project to explore alternative power methods for wireless sensor nodes. Models and designs presented here will enable the application of vibration-based generators in wireless sensor applications. An introductory chapter examines the potential of a range of energy scavenging methods, while the remainder of the book focuses on vibrations as a power source. Commonly occurring vibrations are evaluated for the amount of power that could be scavenged from them, and different methods of converting the kinetic energy inherent in the vibrations are compared. Both piezoelectrical and electrostatic MEMS generator devices are discussed.