Comparative Study of Piezoelectric Transducers for Power Scavengers

Ambient energy scanvengers have the potentials to replace batteries, which have limited lifetime and large volume, and to realize the miniaturized devices. Piezoelectric materials have been testified as a promising candidate for converting vibration energy into electric energy. The conversion efficiency depends on the types of piezoelectric materials and structural designs. PZT, PVDF and MFC cantilevers were studied to compare the performance and applicability under various operational conditions. The resonant frequency of cantilever was calculated and measured to optimize the dimension of cantilevers because the maximum output power density can be achieved when it matches the exciting frequency. The safety factor or maximum operating acceleration (S) is considered to predict the maximum acceleration on the cantilevers without fracture. Results showed that PVDF-and MFC-based devices are around five orders of magnitude higher between PZT-based one. The relationship between the output power density and the dimension of power generator was extensively examined. The output power densities of cantilever-based prototypes fabricated using three piezoelectric materials were obtained through a simple resistive load and the PZT-based device showed the highest value. All three types of devices were demonstrated sufficient power density required to operate microsensor systems in this experimental range.