Macro and Micro Scale Electromagnetic Kinetic Energy Harvesting Generators

Developments in ultra low power electronics, RF communications and MEMS sensors in wireless sensor networks has led to the requirement for in-situ power supplies capable of harvesting energy from the environment. This paper is concerned with generators that harvest electrical energy from the kinetic energy present in the sensor nodes environment. These generators have the potential to replace or augment battery power which has a limited lifetime and requires periodic replacement which limits the placement and application of the sensor node. This paper presents the standard analysis of the energy available in vibration energy generators and discusses the practical implications of reducing electromagnetic generators down in size to the micro level. The practical results from micro devices fabricated under an EU project entitled Vibration Energy Scavenging (VIBES) will be presented. The implications for further reducing the generator in size and employing fully integrated micromachining processes will also be discussed.