Lead-Free LiNbO3 Thick Film MEMS Kinetic Cantilever Beam Sensor/Energy Harvester

Abstract

In this paper, we present integrated lead-free energy converters based on a suitable MEMS fabrication process with an embedded layer of LiNbO3. The fabrication technology has been developed to realize micromachined self-generating transducers to convert kinetic energy into electrical energy. The process proposed presents several interesting features with the possibility of realizing smaller scale devices, integrated systems, miniaturized mechanical and electromechanical sensors, and transducers with an active layer used as the main conversion element. When the system is fabricated in the typical cantilever configuration, it can produce a peak-to-peak open-circuit output voltage of 0.208 V, due to flexural deformation, and a power density of 1.9 nW·mm−3·g−2 at resonance, with values of acceleration and frequency of 2.4 g and 4096 Hz, respectively. The electromechanical transduction capability is exploited for sensing and power generation/energy harvesting applications. Theoretical considerations, simulations, numerical analyses, and experiments are presented to show the proposed LiNbO3-based MEMS fabrication process suitability. This paper presents substantial contributions to the state-of-the-art, proposing an integral solution regarding the design, modelling, simulation, realization, and characterization of a novel transducer.

Microfabrication of piezoelectric MEMS based on thick LiNbO3 single-crystal films

“…The electromechanical coupling of 5%, measured for the LiNbO 3 -Si cantilevers, presents an improvement with respect to previously reported value of 0.7% for (YXlt)/163°/ 90°LiNbO 3 -Si cantilever [43]. The electromechanical coupling of 14.8% was reported for the transducer based on 20 μm thick PZT [2].…”

Material strategies to enhance the performance of piezoelectric energy harvesters based on lead-free materials

“…Further works are undergoing on the optimization and fabrication of bimorph structures to further increase the harvested PD. The first integrated MEMSscale energy converters based on single-crystal LiNbO 3 films were reported last year [172]. LiNbO 3 MEMS cantilevers under flexural deformation with acceleration of 2.5 g have produced a PD of 1.9 nW•mm −3 •g −2 at resonance frequency of 4.1 kHz.…”

3D Printing of Flexible BaTiO3/Polydimethylsiloxane Piezocomposite with Aligned Particles for Enhanced Energy Harvesting

“…Internet of Things (IoT) and wearable electronics have attracted much attention in sensing technology; − however, unsustainable power supply for such sensors has become a serious challenge for their applications. − Traditional power-generation strategies are restricted by lifetime and frequent replacement. − Piezoelectric energy harvesters can convert ambient mechanical energy into electrical energy through a piezoelectric effect. − Piezoelectric ceramics and polymers are mainly used for piezoelectric energy harvesting. , The applications of piezoelectric ceramics, such as lead zirconate titanate (PZT) and barium titanate (BaTiO 3 ), in flexible wearable electronics are still restricted due to their high brittleness, poor flexibility, and low durability. − On the contrary, piezoelectric polymers, especially poly­(vinylidene fluoride) (PVDF) and copolymers, are promising candidates for flexible electronic devices due to their excellent flexibility and thermal stability. , …”