Kari Nurmi1 Jaakko Palosaari1 Heli Jantunen1 Jari Juuti1

1, University of Oulu, Oulu, , Finland

Annually billions of small batteries are replaced and thrown away causing potential environmental threat due to hazardous materials in the batteries. At the same time, their replacement can be expensive as one replacement round may easily exceed the cost of e.g. wireless sensors due to labour cost. Consequently, energy harvesters have been under active research and technology development where the aim has been to replace batteries as a power source or extend their lifetime. In addition, another driving force is to enable truly wireless measurements in applications where conventional solutions are not feasible e.g. rotating parts where cables cannot be used.

In this scheme, piezoelectric energy harvesters have been extensively researched as they provide compact designs and high power density to be utilised in small size electronic devices to power wireless sensors. However, state of the art piezoelectrics contain lead which malign health issues have been previously addressed in Europe by legislations thus possibly compromising the development of future emerging energy harvesting applications. Therefore, new high performance lead-free materials for energy harvesting should be discovered.

In this research, energy harvesting performance of lanthanum and titanium doped flexoelectric BaSrTiO3 ceramics were investigated. Cantilever type harvester components were tested under different vibration and energy levels and stress conditions. The results and power densities were analysed and compared to corresponding PZT ceramic based cantilever harvester at the same conditions. Furthermore, the results were compared against state-of-the-art piezoelectric energy harvesters under their operating schemes.