Piezoelectricity is defined as the production of an electric potential due to pressure on certain crystalline substances such as quartz, Rochelle salt, tourmaline, barium titanate, ammonium dehydrogen phosphate and other ceramic crystals.
This piezoelectric effect is used for measurement of pressure, force or acceleration. The primary interest here is in its use as a pressure sensor.
Quartz is the most commonly used crystal that produces the piezoelectric effect. Synthetic crystals have been developed that produce the same effect and they generally have higher sensitivities than natural crystals.
The nature of the piezoelectric device is the production of electric potential as it is deformed or stressed. In a static condition, its potential drops off, producing an error.
This characteristics limits its used somewhat. As a pressure device, it is most useful were pressure variations occur frequently.
It is particularly suited for measurement of pressure transients in ballistics, in internal combustion engines or in reaction processes where pressures change quickly.
Major advantages of piezoelectric devices are the linear relationship between pressure variation and output voltage and their high frequency response ( as high as 106 Hz for quartz ).
A decide advantage of the piezoelectric device is its sensitivity to temperature variations. Reproducible results are not obtained unless temperatures are kept within close limits.