Electro-Mechanical Characterization and Modeling of a Broadband Piezoelectric Microgenerator Based on Lithium Niobate

• Published in: Sensors (Basel, Switzerland) Switzerland), 2024-04, Vol.24 (9), p.2815
• Main Authors: Panayanthatta, Namanu, Clementi, Giacomo, Ouhabaz, Merieme, Margueron, Samuel, Bartasyte, Ausrine, Lallart, Mickael, Basrour, Skandar, La Rosa, Roberto, Bano, Edwige, Montes, Laurent
• Format: Article
• Language: English
• Subjects: Actuators; Bandwidths; Batteries; Bond strength; broadband energy harvesting; Electric generators; Electrodes; Electrons; Energy; Engineering Sciences; Internet of Things; IoT; lead-free piezoelectrics; Lithium; Lithium niobate; piezoelectric energy harvester; Sensors; Silicon wafers; Vibration
• ISSN: 1424-8220; 1424-8220
• DOI: 10.3390/s24092815

Vibration energy harvesting based on piezoelectric transducers is an attractive choice to replace single-use batteries in powering Wireless Sensor Nodes (WSNs). As of today, their widespread application is hindered due to low operational bandwidth and the conventional use of lead-based materials. The Restriction of Hazardous Substances legislation (RoHS) implemented in the European Union restricts the use of lead-based piezoelectric materials in future electronic devices. This paper investigates lithium niobate (LiNbO3) as a lead-free material for a high-performance broadband Piezoelectric Energy Harvester (PEH). A single-clamped, cantilever beam-based piezoelectric microgenerator with a mechanical footprint of 1 cm , working at a low resonant frequency of 200 Hz, with a high piezoelectric coupling coefficient and broad bandwidth, was designed and microfabricated, and its performance was evaluated. The PEH device, with an acceleration of 1 g delivers a maximum output RMS power of nearly 35 μW/cm and a peak voltage of 6 V for an optimal load resistance at resonance. Thanks to a high squared piezoelectric electro-mechanical coupling coefficient (k2), the device offers a broadband operating frequency range above 10% of the central frequency. The Mason electro-mechanical equivalent circuit was derived, and a SPICE model of the device was compared with experimental results. Finally, the output voltage of the harvester was rectified to provide a DC output stored on a capacitor, and it was regulated and used to power an IoT node at an acceleration of as low as 0.5 g.