Piezoelectric foil

Kymissis et al. have examined the possibility of generation of electrical power parasitically from devices built in a shoe, a wearable subsystem for the soldier. Merits of three different types of piezoelectric devices are compared. They are a unimorph strip piezoceramic composite, a stave of multilayer laminate of PVDF foil, and a shoe-mounted rotary magnetic generator as a part of technology demonstration a piezoelectric embedded shoe has also been postulated to periodically broadcast a digital radio frequency identification (RFID) signal as the wearer walks. 

The actuator part may also be a smart material, such as a piezoelectric bar, placed in a wind foil that changes orientation according to a current imputed by the computer center allowing a machine such as an automobile to handle better and be more fuel efficient. 

Fig. 9.2. The inverse piezoelectric effect. A thin and long quartz plate, QQ, is sandwiched between two tin foils. By applying a voltage to the tin foils, the quartz plate elongates or contracts according to the polarity of the applied voltage. To measure the very small displacement. Curie (1889a) used a lever ABD with a small piece of glass V attached at its end, the displacement of which is then measured with an optical microscope. (After Curie, 1889a.)...

In order to gain a direct experimental approach to probe the internal conversion of P, LIOAS was further developed to afford time-resolved measurements. For this purpose / -polyvinylidene difluoride foil was introduced [81] as a broad-frequency band piezoelectric detector—instead of the previously used ceramic transducers—which permitted for the first time the... 

Polymers that exhibit the piezoelectric effect include polyvinyl chloride, polyvinyl fluoride, and difluor polyethylene. These polymers acquire their properties through technological processing. The thin plastic foil samples are exposed to strong electric fields and then cooled to room temperature. This process results in a polarization of the material. 

Another very promising approach is the use of piezoelectric poljuner materials such as PVDF and its copol3Tneis that usually are extruded into foils... 

Although piezoelectric properties such as relative permittivity and piezoelectric coefficients change with the temperature, the total effect for the calibration of PZT sensors far below the Curie temperature is very small. However, PVDF foils show a significant temperature dependence of the pyroelectric properties in addition to their temperature depending piezoelectric features. Thus PVDF sensors are quite temperature sensitive, and in general, an appropriate temperature compensation is necessary. This behaviour, however, can be improved by special forming and spatial distribution of the PVDF sensors [100]. 

F. Harnish, N. Krocmer. and W. Manthey. Ultrasonic transducers with piezoelectric polymer foil. Sensors and Actuators A 25-27J49-552 (1991). 

As mentioned above the acoustic disturbances generated in the sample are detected by some kind of pressure sensor. In contact with liquid or solid samples these are piezoelectric devices such as lead zirco-nate titanate (PZT), LiNb03 or quartz crystals with a typical responsivity R in the range of up to V bafi or thin polyvinylidene-difluoride (PVF2 or PVDF)-foils with lower responsivity. These sensors offer fast response times and are thus ideally adapted for pulsed photoacoustics. 

Diagnostics Smoked foil, piezoelectric, pressure transducers, photodiodes, ion detectors, fast response thermocouples, gas sampling, and gas chromo to graphy Smoked foil, piezoelectric pressure transducers, photodiodes, ion detectors, fast response thermocouples, gas sampling, and gas chromotography ... 

Piezoelectric polymer film can be used for supplying low power to submicron CMOS electronic devices. Klimiec et al. show that mechanical energy can be converted from walking, by using a copolymer polyethylene-polypropylene (PE-PP) shoe insole. They claim that the amount of electric energy obtained from a PE-PP foil of a thickness of 11 om for a single step of a duration of 1 s amounts to 340 nJ. 

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