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LiNbO3 has been little studied for the piezoelectric energy harvesting applications. Although, it is a cheap piezoelectric material without lead and toxic elements, and it beneficiates of technological maturity in single crystal fabrication for optical and acoustic applications. In this letter, we propose to investigate a (YXlt)/128°/90° LiNbO3 cut as it offers a transverse piezoelectric coupling of k23 = 0.49 which is comparable to that of commonly used PZT ceramics. A flexible beam of 65 mm length and tip mass made of LiNbO3 thick film bonded on silicon was studied under 0.1 g sinusoidal acceleration. The beam presented an open-circuit resonance frequency of 105.9 Hz and a displacement up to 1.5 mm. In the frame of single degree of freedom lumped model with rectifying bridge, the electromechanical coupling of the device (km 2 ), the figure of merit 𝑘 𝑚 2 𝑄 and the normalized average power density were compared to both Pb-based and Pb-free current devices. The generated power density by our device was 965 µW/cm²/g², which is among the highest reported values compared to both Pb-and Pb-free vibrational harvesting devices.

HighlightsThe paper provides a novel design of an energy harvesting device for egadgets Surrogate optimization is carried for global maximization of the device's performance The concept is validated using analytical, numerical, and experimental approaches Power generation can reach up to 0.3 W when a 10.2" tablet is considered at 45

The huge number of electronic devices called the Internet of Things requires miniaturized, autonomous and ecologically sustainable power sources. A viable way to power these devices is by converting mechanical energy into electrical through electro-active materials. The most promising and widely used electro-active materials for mechanical energy harvesting are piezoelectric materials, where the main one used are toxic or not biocompatible. In this work, we focus our attention on biocompatible and sustainable piezoelectric materials for energy harvesting. The aim of this work is to facilitate and expedite the effort of selecting the best piezoelectric material for a specific mechanical energy harvesting application by comprehensively reviewing and presenting the latest progress in the field. We also identify and discuss the characteristic property of each material for each class to which the material belong to, in terms of piezoelectric constants and achievable power.

Over the past four decades, energy microsources based on piezoelectric energy harvesting have been intensively studied for applications in autonomous sensor systems. The research is triggered by the quest for replacing standard lead-based piezoelectric ceramics with environmentally friendly lead-free materials and potential deployment of energy-harvesting microsystems in internet of things, internet of health, “place and leave” sensors in infrastructures and agriculture monitoring. Moreover, futher system miniaturization and co-integration of functions are required in line with a desired possibility to increase the harvested power density per material volume. Thus, further research efforts are necessary to develop more sustainable materials/systems with high-performance. This paper gives a comprehensive overview on the processing and functional testing the lead-free bulk materials and thin films and discuss their potential in the applications in the stress- and strain-driven piezoelectric energy harvesting. This includes the methodology of estimation of the substrate clamping and orientation/texture effects in the thin films, and identification of orientations offering high figure of merit. The ability to control film orientation of different lead-free materials is reviewed and the expected piezoelectric performances are compared with the ones reported in literature.

Pyroelectric materials are very promising for thermal energy harvesting applications. To date, lead‐based systems are the foremost studied materials in this field. A facile and simple metal organic chemical vapor deposition route is applied for the fabrication of lead‐free, high quality, epitaxial Bi(1−x)DyxFeO3 (x = 0, 0.06, 0.08, 0.11) thin films deposited on conductive SrTiO3:Nb (100) single crystal substrates. The films are studied by structural, morphological, compositional, and functional characterization. The correlation between the Dy‐doping amount and the dielectric properties is thoroughly investigated. Unipolar polarization–electric field loops and permittivity measurements show the important impact of Dy on ferroelectric, dielectric, and pyroelectric properties. Dy doping increases considerably the dielectric response, but much more the pyroelectric coefficient, up to a concentration of 8% Dy. The films are self‐poled, which is an ideal situation for pyroelectric applications. The best figure of merit for pyroelectric energy harvesting, FE, is 82 J m−3 K−2, showing a factor increase of 2.6 as compared to the undoped film of the sample series. It constitutes a factor 4.5 improvement as compared to previous results obtained on BiFeO3 based thin films.

Single-crystalline LiNbO3 films were studied as a pyro- and piezo-electric transducer for energy harvesting applications. Two types of devices: piezoelectric cantilever (PiEH) and pyroelectric chip (ThEH) were microfabricated. Different types of characterization were done, starting from a comparison of finite element method (FEM) simulated eigen-frequencies of cantilever beam and optical vibrometer measurements. According to electrical characterization, resonance frequencies of two cantilevers with different thickness were 1.26 kHz and 485 Hz with generated spontaneous power of 14 μW and 4 μW at 275-300 kΩ, respectively. Finally thermal characterization of pyroelectric samples showed voltage amplitudes ranging from 1 to 2.5mV in the temperature range of 50-200 °C.

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.