Piezoelectric characterization of ain thin films on silicon substrates

The electric field induced deformations of thin piezoelectric, aluminium nitride (AlN) layers, on top ofa silicon substrate, were studied by numerical calculations and interferometric measurements. Our calculationby finite element method demonstrates that substrate deformation under the top electrode may be comparableto the deformation in the thin AlN layer, for a given applied voltage. Simulations also show the effect of aclamped or free substrate condition and the relative contributions of d33 and d31 piezoelectric constants. ALaser scanning vibrometry technique was used to measure deformations in the top surface with sub-picometervertical resolution. By comparing calculations and experimental data, quantitative information about both d31and d33 constants can be obtained

Simulation and laser vibrometry characterization of piezoelectric AlN thin films

In this paper, the electric field induced deformations of sputter-deposited piezoelectric aluminum nitride thin films sandwiched between electrodes on top of a silicon substrate are studied by numerical calculations and scanning laser interferometric measurements. In our calculations based on the finite element method, the results show the displacement of the top and bottom surfaces of both the thin film and the substrate, for either a free or a perfectly clamped structure. The confirmation that the bottom surface of the film is deformed reveals the limitations of techniques that only access the top surface, as well as the double-beam interferometric configuration, under specific conditions. In addition, the simulations demonstrate the dependence of the displacements on the size of the upper electrode and the contribution of the transverse piezoelectric coefficient d31 to the features of the displacement profiles. A laser scanning vibrometry technique was used to measure deformations on the top surface with subpicometer vertical resolution. By comparing the calculated and the experimental displacement profiles, an advanced approach is discussed to obtain accurate quantitative information of both coefficients d31 and d33

Advanced determination of piezoelectric properties of AlN thin films on silicon substrates

Piezoelectric deformations of thin, aluminum nitride (AlN) layers, on top of a silicon substrate, were studied by numerical calculations and interferometric measurements. Our calculation by finite element method demonstrates that substrate deformation under the top electrode may be comparable to the electric field induced deformation in the thin AlN layer, for a given applied voltage. Simulations also show the effect of a clamped or free substrate condition and the relative contributions of d33 and d31 piezoelectric constants. A Laser scanning vibrometry technique was used to measure deformations in the top surface with sub-picometer vertical resolution. By comparing calculations and experimental data, quantitative information about both d33 and d31 constants can be obtained

Reutilización a escala micrométrica de la energía solar y mecánica de nuestro entorno y su influencia en el desarrollo industrial

El proyecto persigue varias finalidades: ofrecer a los alumnos la posibilidad de adquirir destrezas en el uso de un software que les haga más fácil comprender algunos de los contenidos del currículo de la asignatura de Tecnología Industrial; diseñar dos unidades didácticas para proponer al alumnado, con ellas se llevará a la práctica la primera finalidad; conseguir en el alumnado un interés por la investigación y la innovación y que adquirieran destrezas en el uso de las TIC para exponer sus ideas públicamente con la mayor eficiencia y claridad posibles. Se busca que los contenidos meramente teóricos del currículo como la fabricación de circuitos integrados, el comportamiento de materiales piezoeléctricos o bimetálicos, el funcionamiento de las placas solares y de ello la posibilidad de convertir energía solar en eléctrica o la reutilización de la energía que nos rodea sea lo más práctico posible. Las posibilidades que ofrecen los scavengers piezoeléctricos para convertir energía mecánica de vibración, en energía eléctrica para recargar baterías y permitir el funcionamiento autónomo de equipos electrónicos es algo innovador, interesante y atractivo para el alumnado. El trabajo del profesorado, las instalaciones que se ponen a disposición de los alumnos de la ETS de Ingenieros Industriales de Ciudad Real y el interés mostrado por los alumnos, confirman que se cumple con la finalidad que se perseguía con el proyecto. La instalación de una placa solar en el IES Ribera de Bullaque que mantiene iluminado un hall exclusivamente con energía solar es un logro más de este proyecto, sobre todo, teniendo en cuenta el interés de los alumnos durante su instalación.Castilla La ManchaConsejería de Educación, Ciencia y Cultura. Viceconsejería de Educación y Cultura. Servicio de Documentación; Bulevar del Río Alberche, s. n. - 1 Planta; 45071 Toledo; +34925286045; +34925247410; [email protected]

Hybrid energy storage system for wireless sensor node powered by aircraft specific thermoelectric energy harvesting

This paper describes an approach for efficiently storing the energy harvested from a thermoelectric module for powering autonomous wireless sensor nodes for aeronautical health monitoring applications. A representative temperature difference was created across a thermo electric generator (TEG) by attaching a thermal mass and a cavity containing a phase change material to one side, and a heat source (to represent the aircraft fuselage) to the other. Batteries and supercapacitors are popular choices of storage device, but neither represents the ideal solution; supercapacitors have a lower energy density than batteries and batteries have lower power density than supercapacitors. When using only a battery for storage, the runtime of a typical sensor node is typically reduced by internal impedance, high resistance and other internal losses. Supercapacitors may overcome some of these problems, but generally do not provide sufficient long-term energy to allow advanced health monitoring applications to operate over extended periods. A hybrid energy storage unit can provide both energy and power density to the wireless sensor node simultaneously. Techniques such as acoustic-ultrasonic, acoustic-emission, strain, crack wire sensor and window wireless shading require storage approaches that can provide immediate energy on demand, usually in short, high intensity bursts, and that can be sustained over long periods of time. This application requirement is considered as a significant constraint when working with battery-only and supercapacitor-only solutions and they should be able to store up-to 40-50J of energy. © (2013) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only