During the operation with capacitive pressure sensors, the pressure to be measured effects a variation of the distance between flexible membrane and a fixed electrode. By this, the capacity between these two components is changed. In comparison with other physical principles, capacitive pressure sensors are characterized by a very high precision and an extremely good resolution especially for the measurement of very small absolte and differential pressures.
In principle, the characteristic of capacitive pressure sensors is not linear. Some manufacturers solve this problem by using special electronics. HOFFRICHTER developed a certain sensor design which guarantees a relatively wide linear range.
For this reason it was possible to adapt the electronic optimally for a linear operation. So, electronic compensation components which are likely to negatively influence the stability are unnecessary.
The PasCal pressure sensor is made of a ceramic substrate with silver-palladium thick layer electrodes. The membrane is made of a special steel or ceramic and is fixed by glass rings.