Displacement measuring methods

Capacitive ceramic sensor

In contrast to the resistive method, the deformation itself is not evaluated, but rather a change in distance that results from the deformation of the membrane.

Symbole:

d - Abstand der Kondensatorabdeckungen
p - Druck
A - Oberfläche
εr - Verformung der Membran


The capacitive sensor consists of a ceramic base body (Al2O3), the design of which represents a capacitor made from metallic-coated surfaces. The top capacitor plate is the fixed plate (Cp electrode) and the membrane is the second plate (counter electrode). The distance ring connects the membrane to the base body and defines the plate distance. When pressure is applied to the membrane, the plate distance changes, and therefore the capacitance changes. The membrane stroke is only approx. 30 μm. This design is suitable for low pressures in the single-figure millibar range. The overload capacity is very high since the membrane can only move as far as the counter electrode, where it then clings.

Fig.2:JUMO. Capacitive pressure measurement method

When pressure is applied to the membrane, the plate distance changes, and therefore the capacitance changes. The membrane stroke is only approx. 30 μm. This design is suitable for low pressures in the single-figure millibar range. The overload capacity is very high since the membrane can only move as far as the counter electrode, where it then clings.

JUMO. JUMO dTRANS p02 CERAMIC pressure transmitter series (404387)