This paper reviews concepts and applications in low-power electronics and energy harvesting technologies. Various piezoelectric materials and devices for small power generators useful in renewable electricity are presented. The vibrating piezoelectric device differs from the typical electrical power source in that it has capacitive rather than inductive source impedance, and may be driven by mechanical vibrations of varying amplitude. In general, vibration energy could be converted into electrical energy using one of three techniques: electrostatic charge, magnetic fields and piezoelectric. A low power piezoelectric generator, having a PZT element was realised in order to supply small electronic elements, such as optoelectronic small devices, LEDs, electronic watches, small sensors, interferometry with lasers or Micro-electro-mechanical System (MEMS) array with multi-cantilevers.
The results of research into Surface Acoustic Waves (SAW) devices have been recognized for their efficiency and versatility in the electrical signals processing. Actual progress in the industrial application of piezoelectric materials such as Lithium Niobate (LiNbO3), Langasite (LGS), Lanthanum-Gallium Silicate La3Ga5SiO14 and Gallium Orthophosphate (GaPO4), allows the manufacturing of devices with piezoelectric performances, which overcome the limits obtained with quartz crystals. The single crystal materials have a long term high stability - near to infinite – and moreover, some of these have an excellent behavior with temperature variation. Today, GaPO4 with its properties is by far the best suited piezoelectric material to be used in sensor applications for machine monitoring and pressure measurements, at high temperatures. SAW micro devices based on GaPO4 operate at temperatures of up to 8000C. For a particular case, of harsh-environment applications, additional challenges need to be overcome, relating to substrate integrity and operation, thin film electrode fabrication, device packaging, and sensor interrogation. This paper reviews the novel progres in the area of (SAW) sensors for harsh conditions.
This paper presents an experimental study on the behavior of cylindrical piezoceramic transducers exposed to dynamic mechanical shocks. The piezoceramic materials under study are solid solutions of Pb(ZrxTi1-x)O3 and present direct piezoelectric effect. In the laboratory were made experiments with cylinders of BaTiO3 and PZT ceramics, for determination of their behavior at mechanical shocks. The shocks resistance of piezoceramic materials is essential in those applications that involve dynamic stress. The tests on ceramics have sought to establish the capacity of a piezoceramic element to resist at recurrent hits and to absorb energy.
This paper presents an experimental study on the behavior of piezoceramics type PZT, having a high compliance, and their application for an optoelectronic micropositioner device with piezoceramic transducer. The piezoelectric ceramics are crystallite conglomerate ferroelectrics materials with random orienting. In the laboratory we have realized PZT ceramics with various additions (Ni, Bi, Mn), presenting high compliance, for optoelectronic micropositioning device in micrometry displacements. The experimental transducers, realized like stacks of 30 divided by 35 pieces of PZT thin disks, supplied with 0 divided by 1000 V voltages, have produced 0 divided by 15 micrometers displacements.
This paper presents a bimorph transducer made of a PZT ceramic (titanate zirconate of lead) material, having a high compliance. There are revealed some properties of piezoceramic we have used (which is obtained in the laboratory) and the way to achieve the transducer. The transducer is an electromechanical one and it works on the basis of the reverse piezoelectric effect, converting the electrical power into a mechanical vibration in the range of tens of microns. The low power is fit together with a He-Ne laser in order to increase vibration amplitude and to modify the trajectory of the light beam from distance. This system is very sensitive: it starts vibrating at 5 V voltage. The piezoceramic bender transducers have two major advantages: (1) the ability to generate electrical signals from mechanical and acoustic sources of low impedance; and (2) the ability to develop relatively large motions and low forces with small electrical excitation. This system with piezoceramic bender transducer may be used in medical applications too.
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