Energy harvesting technologies for structural health monitoring applications

This paper reviews energy harvesting technologies for structural health monitoring applications. Structural health monitoring (SHM) is the process of damage detection in machinery, aerospace, and civil structures. There is a great deal of interest across a broad section of industries in obtaining technology that can be used to monitor the health of machinery and structures. In particular, the need for autonomous monitoring of structures has been ever-increasing in recent years. Autonomous SHM systems typically include embedded sensors, data acquisition, wireless communication, and energy harvesting systems. Among all of these components, this paper focuses on the energy harvesting technologies. Since low-power sensors and wireless communications are used in most recent SHM systems, a number of researchers have recently investigated techniques to extract energy for such stand-alone, self-powered systems from the local environment. Ambient energy sources could be vibration, thermal gradient, sun, wind, pressure, etc. If the structure has a rich enough loading, then it may be possible to extract the needed power directly from the structure itself. Harvesting energy using piezoelectric materials by converting applied stress to electricity is most common. In a structural health monitoring application, the piezoelectric material would be stressed due to vibrations or direct loading in a structure. Other methods to harvest energy such as electromagnetic, magnetostrictive, or thermoelectric generator is also reviewed. Lastly, an energy harvester with frequency tuning capability is demonstrated.