The increasing interest on autonomous working wireless sensor systems has led to an immense achievement in the developing of energy harvesters. One promising principle for energy harvesting is the conversion of environmental mechanical vibrations into electric energy by the use of piezoelectric materials. Besides mechanical forces further environmental energy sources, like stray magnetic fields, have to be considered in order to further improve the overall harvesting performance. Energy harvesters based on composites containing a piezoelectric and a hard magnetic phase and executed as a one side clamped cantilever are able to convert both, mechanical vibrations and magnetic fields into electrical power. The hard magnetic phase converts the external magnetic field by using attractive and repulsive forces into a bending of the cantilever.
We present a comparison of different piezoelectric materials for energy harvesters based on a concept using external magnetic fields. The study investigates AlN, AlScN and PZT with respect to the generated output power as a function of the applied external magnetic field. Furthermore, the generated output power will be compared with the figure of merits given by the piezoelectric and dielectric properties of the investigated materials.