MEMS-Based Multi-Modal Vibration Energy Harvesters for Ultra-Low Power Autonomous Remote and Distributed Sensing

In this contribution we discuss the implementation of a novel MEMS-based EH (Energy Harvester) concept within an already existing technology platform available at the ISAS Institute (TU Vienna, Austria). The device, already presented by the authors, exploits the piezoelectric effect to convert environmental vibration energy into electricity, and presents multiple resonant modes in the frequency range of interest (i.e. below 10 kHz). The experimental characterization of sputter deposited AlN (Aluminum Nitride) piezoelectric thin-film layer is reported, leading to the extraction of material properties parameters. Such values are then incorporated in the FEM (Finite Element Method) model of the EH, implemented in Ansys WorkbenchTM, in order to get reasonable estimates of the converted power levels achievable by the proposed device solution. Multiphysics simulations indicate that extracted power values in the range of several μW can be addressed by the MEMS EH concept when subjected to mechanical vibrations up to 10 kHz, operating in closed-loop conditions (i.e. piezoelectric generator connected to a 100 kΩ resistive load). This represents an encouraging result, opening up the floor to exploitations of the proposed MEMS EH device in the field of WSNs (Wireless Sensor Networks) and zero-power sensing nodes. Comparisons of simulated and measured extracted power performance will be carried out as soon as the fabrication process of physical samples will be accomplished.