Split-electrode piezoelectric scavengers for harvesting energy from torsional motions

Abstract

As most of cantilever scavengers are limited in working in bending mode, it motivates the idea to develop a device that can work with torsional motions. From the finite element analysis, it is found that the torsional modal frequency is near the bending mode frequency, which makes it possible to widen the working frequency range. By using the coupled piezoelectric-circuit finite element method, the harmonic performances of bulk and split electrode devices are quantitatively characterised. The maximum output voltages and power for split-electrode devices are calculated to be 26.7V, 29.35V and 0.023W, which present much more advantages over the bulk-electrode device(1.21V and 43.3μW correspondingly). In this analysis, it is deduced that the cancelling effect occurs across the surfaces of bulk electrodes. For further validation, transient analysis is conducted and it proved that average output power of split-electrode device is almost 25.35% higher than that in bulk electrode device.