The ceramic-capacitive measuring cell consists of a base body, two capacitor layers, a glass solder and a membrane.
The capacitor layers on the base body and membrane are similar to a plate capacitor and form a measurement and reference capacitor. When pressure is applied, the distance between the membrane and the base body changes and this changes the capacitance between the electrodes. This change in capacitance is evaluated and then processed into a signal common in industry.
In these measuring cells, strain gauges in the form of resistors are attached to the back of the stainless steel membrane and connected as a Wheatstone bridge. This can be implemented as a thick layer or a thin film. As soon as the measuring cell is pressurised, the membrane deforms. This changes the output signal of the bridge circuit proportionally, which in turn is measured by the electronics and converted into an output signal common in industry.
These measuring cells make use of the piezoresistive effect. It describes the change in the electrical resistance of a material due to pressure or tension. This change in resistance is recorded with a bridge circuit and converted into an output signal that is common in industry. The piezoresistive silicon measuring cell is bonded to a printed circuit board, which is coated to be universal media-resistant (polluted air, oil, water, cooling lubricant, etc.).