A similar effect is obtained by applying a suitable stress to th

A similar effect is obtained by applying a suitable stress to the ceramic, as the piezoelectric effect has different signs in antiparallel domains.Figure 2.Scheme of the CCP and its domains distributed around the Pt-wire.When the CCP is poled, it originates a great concentration of domains on the Pt-wire because the dipoles are oriented over all its external part. These concentrations achieve free flux charges around the Pt-wire when CCP is excited by stress on its side face.Considering that ferroelectric and piezoelectric materials can be used as sensors and actuators, piezoelectric pressure and acceleration sensors, as well as a variety of piezo-vibrators, are now commercially available.

The development of ultrasonic motors for a variety of new applications has been dramatic and widespread in recent years.

Among piezoelectric ceramics, CCP offers a great variety of applications in medical physics such as the human pulse detection sensor known as PZPG.In medical physics, micro-circulation of skin blood is a subject of considerable interest due to its role in human metabolism, blood transport from and to the tissue and its role as a liquid coolant of the body in the thermoregulation process.There are several techniques which are used to follow the blood flow in living tissues [5]. Piezoelectric methods seem to be the most promising for skin microcirculation studies; one advantage of piezoelectric sensors is that they can be used for true dynamic measurements due their wide range of frequency operation.

Therefore, the analysis of the skin mechanic pulse piezoelectric detection provides valuable selective information Entinostat on blood flow on upper skin layers, cutting off the influence of the deeper arteries and veins [6].The non-invasive piezoelectric method uses the mechanical signals for temporal analysis of the skin blood volume pulsations. The periodical increase of blood volume in micro-vessels Brefeldin_A due to their dilatation during the systolic raise of pressure with the following diastolic contraction over each heartbeat causes corresponding changes in the absorption of the mechanical signals which travel within the working volume.

The measurement of the blood flow is related to the measurement of changes in volume which occur in any part of the body as result from the pulsations of blood with each heartbeat. The instruments that measure volume changes or provide outputs that can be related to them are called plethysmographs. Plethysmographs respond to changes in volume, but there are several devices that in fact measure some other variables related to volume rather than volume itself.

Leave a Reply

Your email address will not be published. Required fields are marked *


You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>