EH009

Wireless sensors are becoming extremely popular for their ability to be employed in hostile and inaccessible locations. To power these sensors, a suitable self-sustainable power source is required, and vibration energy harvesting shows the potential to be the power source. While a general requirement independent of the energy conversion process is that the vibration energy harvesting device should operate in resonance at the excitation frequency, many current designs are based on a single resonant frequency, limiting their performance and potential applications. While several techniques have recently demonstrated tuning of the resonant frequency of the harvesting device, such tuning must be considered in terms of the energy cost of the tuning operation and its impact on the effective power density of the device. Here piezoelectric cantilever array with magnetic tips are coupled in a novel fashion by means of magnetic force for tuning with respect to the ambient environmental vibration. Through this mechanism it is feasible to both increase and decrease the stiffness of the beam, thereby enabling tuning to lower or higher frequencies as necessary. Further the technique is semi-active, consuming energy only when a frequency tuning is required, making the device highly efficient. In this work, designs for high efficiency multi-beam arrays consistent with a tunable energy harvesting methodology are presented, each of which utilizes the application of magnetic force as the tuning mechanism.