Energy harvesting is the process of converting energy that will otherwise be dissipated into the ambient environment, into useful energy to do work. I shall focus this discussion on motion-based energy harvesting. Motion-based energy harvesting is the process of converting dissipated mechanical energy into electrical energy. Sources of mechanical energy include the ocean waves, wind, human motion, vehicular traffic, and vibrations in buildings and bridges. This source of energy is ubiquitous and pervasive, and yet, it is one of the least developed energy harvesting technology.