A broadband and two-dimensional vibration energy harvester using multiple magnetostrictive/piezoelectric composite transducers

There is growing interest in energy scavenging from natural vibration sources to power autonomous wireless telemetry devices. Vibration energy is typically converted into electrical energy using piezoelectric, electromagnetic, or electrostatic transduction mechanisms [1]. Despite the transduction mechanisms and novel structures, there is still an obstacle facing realistic implementation in most of the vibration-based energy harvester, because they are deigned to harvest energy in a single direction of the ambient vibrations. But a vibration source in real environment may exhibit several motion directions over time. Hence, they may not generate power effectively in the case of a motion with multiple or time-variant motion directions. To address this issue, Moss et al. proposed a bi-axial oscillator to extract vibration energy with arbitrary motion directions in a plane [2]. However, the AISI 52100 ball oscillating on the surface of the Terfenol-D will damage the transducer inevitably, and the bandwidth of the harvester was narrow (about 1 Hz). Magnetoelectric (ME) transducers (composed of magnetostrictive/ piezoelectric laminate composites) were originally intended for magnetic field sensors but have recently been used in vibration energy harvesting. Therefore, we report on a design for an energy harvester using ME transducers, in which only one vibrating body is used to extract the ambient vibration energy with arbitrary in-plane motion directions, and the frequency bandwidth can be enhanced by nonlinear behavior of the magnetic force .