Enabling technology for high-quality piezoMEMS

ENPIEZO was focused on developing piezoelectric-based energy-harvesting (EH) devices to provide a remote source of electricity for various applications by exploiting waste vibrations. The project brought together four partners with diverse expertise, enabling a comprehensive approach for developing the materials and designing a device. Owing to its excellent piezoelectric properties, Pb(Mg1/3Nb2/3)O3–PbTiO3 (PMN-PT) was selected as the functional layer for the device and grown as either a thin epitaxial layer on Si or as a thicker polycrystalline layer on stainless steel substrates. Mathematical modelling of EHs for epitaxial and polycrystalline layers was performed for the longitudinal and transverse modes of EH operation. A device design with the optimal layer thickness, electrode configuration and proof mass was developed using calculated and experimentally determined mechanical properties of the materials. Along with the buffer layers, necessary to integrate epitaxial PMN-PT with Si, the growth was first studied on a laboratory-scale pulsed-laser deposition (PLD) system, examining the crystal structure from an atomic to a macroscopic scale, along with the chemical composition of the films and the resulting functional properties. The growth was then transferred to an industrial scale PLD, where high-quality PMN-PT thin films were grown on large (8’’) wafers. In parallel, thicker polycrystalline PMN-PT was grown on stainless steel using aerosol deposition. Test devices were constructed from the prepared samples and the experimental results were compared to the mathematical model. A power output of 90 μW was achieved at 0.5 g acceleration for 10 μm thick films with a quality factor of 147. The resonant frequency was 98 Hz. A device model was proposed, with the integration of all components of the EH, enabling its use various applications, such as in transformers, bearings rotary systems, encoders, etc.

The partners have published 7 ISI papers (three additional papers are in preparation) and presented their work at 28 international conferences. Additionally, two doctoral degrees and two masters degrees have been achieved as a result of the project. For more information, please visit the project’s website -> http://enpiezo.ijs.si/

Project Details