Up-scaled macro-device implementation of a MEMS wideband vibration piezoelectric energy harvester design concept

In this work, we discuss a novel mechanical resonator design for the realisation of vibration Energy Harvester (EH) capable to deliver power levels in the mW range. The device overcomes the typical constraint of frequency narrowband operability of standard cantilevered EHs, by exploiting a circular-shaped resonator with an increased number of mechanical Degrees Of Freedom (DOFs), leading to several resonant modes in the range of vibrations of interest (i.e. multi-modal wideband EH). The device, named Four-Leaf Clover (FLC), is simulated in Ansys Workbench™, showing a significant number of resonant modes up to vibrations of around 2 kHz (modal eigenfrequencies analysis), and exhibiting levels of converted power up to a few mW at resonance (harmonic coupled-field analysis). The FLC mechanical structure, along with cantilevered test structure, is realised by micro-milling of an Aluminium foil. PolyVinyliDene Fluoride (PVDF) film sheet pads are assembled in order to collect first experimental feedback on generated power levels. The FLC and cantilevered EH test structures are characterised experimentally with a measurement setup purposely developed, showing encouraging performance related to the technology chosen for the realisation of EH, thus paving the way for full validation of the macro-FLC concept.