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

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.

LiNbO Thin Films through a Sol-Gel/Spin-Coating Approach Using a Novel Heterobimetallic Lithium-Niobium Precursor.

Lithium niobate is a lead-free material which has attracted considerable attention due to its excellent optical, piezoelectric, and ferroelectric properties. This research is devoted to the synthesis through an innovative sol-gel/spin-coating approach of polycrystalline LiNbO films on Si substrates. A novel single-source hetero-bimetallic precursor containing lithium and niobium was synthesized and applied to the sol-gel synthesis.

Integration of epitaxial LiNbOthin films with silicon technology.

Development of bulk acoustic wave filters with ultra-wide pass bands and operating at high frequencies for 5and 6generation telecommunication applications and micro-scale actuators, energy harvesters and sensors requires lead-free piezoelectric thin films with high electromechanical coupling and compatible with Si technology. In this paper, the epitaxial growth of 36°Y-X and 30°X-Y LiNbOfilms by direct liquid injection chemical vapour deposition on Si substrates by using epitaxial SrTiOlayers, grown by molecular beam epitaxy, has been demonstrated. The stability of the interfaces and chemical interactions between SrTiO, LiNbOand Si were studied experimentally and by thermodynamical calculations.

Microfabrication of piezoelectric MEMS based on thick LiNbOsingle-crystal films.

Microfabrication procedure of piezoelectric micro electro-mechanical systems based on 5m thick LiNbOfilms on SiO/Si substrate at wafer scale including deep dry etching of thick LiNbOfilms by implementing pulsed mode of Ar/SFgas was developed. In particular, two (YXlt)/128°/90°LiNbO-Si cantilevers with tip mass were fabricated and characterized in terms of resonance frequency (511 and 817 Hz), actuation and acceleration sensing capabilities. The quality factor of 89.

Acousto-electric measurements at 2.5 GHz on graphene transferred onto YX128°-LiNbO.

Surface acoustic wave delay lines with an operational frequency of 2.5 GHz have been designed to measure the acousto-electric transport of carriers in graphene transferred onto YX128°-LiNbOpiezoelectric substrate. The monolayer of graphene on LiNbOpresented sheet resistance in the range of 733-1230 Ω/□ and ohmic contact resistance with gold of 1880 to 5200 Ωm.

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

In this paper, we present integrated lead-free energy converters based on a suitable MEMS fabrication process with an embedded layer of LiNbO. 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.

A Self-Powered and Battery-Free Vibrational Energy to Time Converter for Wireless Vibration Monitoring.

Wireless sensor nodes (WSNs) are the fundamental part of an Internet of Things (IoT) system for detecting and transmitting data to a master node for processing. Several research studies reveal that one of the disadvantages of conventional, battery-powered WSNs, however, is that they typically require periodic maintenance. This paper aims to contribute to existing research studies on this issue by exploring a new energy-autonomous and battery-free WSN concept for monitor vibrations.

Microscopic imaging along tapered optical fibers by right-angle Rayleigh light scattering in linear and nonlinear regime.

The evolution of the light intensity along an optical waveguide is evaluated by analysing far-field right-angle Rayleigh light scattering. The method is based on point by point spectral mapping distributed along the optical waveguide with a micrometric spatial resolution given by a confocal microscope, a high spectral resolution given by a spectrometer, and a high signal-to-noise ratio given by a highly cooled detector. This non-destructive and non-invasive experimental method allows the observation of the general Rayleigh scattering profile of the optical waveguide in a nominal operation, i.

Multi-dimensional constrained energy optimization of a piezoelectric harvester for E-gadgets.

This paper addresses the design optimization process of an energy harvesting device for scavenging energy from an e-gadget, utilizing its "rocking" motion. The plucking mechanism inspired by the frequency up-conversion technique provides initial displacement exciting piezoelectric beams and increases the total number of excitations multiple times. The harvester is designed in conjunction with the multidimensional surrogate optimization algorithm to maximize the device's performance considering the geometrical features of the concept and the constrained operating environment.

Identification of LiNbO₃, LiNb₃O₈ and Li₃NbO₄ phases in thin films synthesized with different deposition techniques by means of XRD and Raman spectroscopy.

Phase composition of epitaxial/textured LiNbO3 films on sapphire substrates, grown by pulsed laser deposition, atmospheric pressure metal organic chemical vapor deposition and pulsed injection metal organic chemical vapor deposition was studied by conventional x-ray diffraction techniques. Raman spectroscopy, being highly sensitive to the symmetry of materials, was used as a countercheck in the compositional analysis. The wavenumbers of Raman modes of LiNb3O8 and Li3NbO4 phases were identified from Raman spectra of synthesized powders.

Raman spectroscopy and X-ray diffraction studies of stress effects in PbTiO3 thin films.

A systematic study of domain structure and residual stress evolution with film thickness and of phase transition in c/a epitaxial PbTiO(3)/LaAlO(3) films using X-ray diffraction and Raman spectroscopy is reported. Both techniques revealed that the films are under tensile residual stress in the film plane and that a-domains are more stressed than c-domains. The two components of the large A(1)(TO) Ramanmodes are associated with a- and c-domains and their intensity ratio correlates to the volume fraction of a-domains.