Multi-mode piezoelectric energy harvesters for wireless sensor network based structural health monitoring

Abstract

For sensor operation or remote interrogation of existing infrastructures, power is one of the key issues in wireless sensing technology. The novel energy harvesting technique and its integration with wireless sensing systems are vital to the next generation structural health monitoring systems. Energy harvesting devices convert the ambient energy surrounding the wireless sensors into electrical energy to extend the lifetime or reach unlimited lifespan of wireless sensors. Mechanical vibrations, existing almost everywhere, have been investigated as a promising energy source for wireless sensors in many applications. Piezoelectric generators are the primary method for converting the vibration energy into electrical energy. Most piezoelectric vibration energy harvesters studied so far are based on simple cantilever-based design with resonant frequency matching the environmental resonant frequency. However, the energy conversion efficiency of this type of vibration energy harvester drops dramatically if the environmental frequency and the frequency of the energy harvester are mismatched. This paper proposes a novel multi-mode piezoelectric vibration energy harvester that is suitable for structural health monitoring in an environment with multiple dominant vibration modes. The multi-mode piezoelectric vibration energy harvester has distributed stiffness and mass and has multiple resonant frequencies adapted to the environmental vibration modes. A multi-mode energy harvester with two interested resonant modes is used as an example to demonstrate this new concept. The multi-mode energy harvester is modeled using Finite Element Method. The efficiency of the multi-mode piezoelectric energy harvester is compared with that of existing cantilever-based piezoelectric energy harvester.