Proceedings Article | 17 May 2013
Proc. SPIE. 8763, Smart Sensors, Actuators, and MEMS VI
KEYWORDS: Microelectromechanical systems, Electronics, Microsystems, Resonators, Silicon, Energy harvesting, Modal analysis, Finite element methods, Electromagnetism, Instrument modeling
The aim of this contribution is to report and discuss a preliminary study and rough optimization of a novel concept of
MEMS device for vibration energy harvesting, based on a multi-modal dynamic behavior. The circular-shaped device
features Four-Leaf Clover-like (FLC) double spring-mass cascaded systems, kept constrained to the surrounding frame
by means of four straight beams. The combination of flexural bending behavior of the slender beams plus deformable
parts of the petals enable to populate the desired vibration frequency range with a number of resonant modes, and
improve the energy conversion capability of the micro-transducer. The harvester device, conceived for piezoelectric
mechanical into electric energy conversion, is intended to sense environmental vibrations and, thereby, its geometry is
optimized to have a large concentration of resonant modes in a frequency range below 5-10 kHz. The results of FEM
(Finite Element Method) based analysis performed in ANSYS<sup>TM</sup> Workbench are reported, both concerning modal and
harmonic response, providing important indications related to the device geometry optimization. The analysis reported in
this work is limited to the sole mechanical modeling of the proposed MEMS harvester device concept. Future
developments of the study will encompass the inclusion of piezoelectric conversion in the FEM simulations, in order to
have indications of the actual power levels achievable with the proposed harvester concept. Furthermore, the results of
the FEM studies here discussed, will be validated against experimental data, as soon as the MEMS resonator specimens,
currently under fabrication, are ready for testing.