The pressure sensor is an assembly of a micromachined silicon part and pyrex™ glas. Four polysilicon Piezo Resistances have been implemented, on top of silicon, just above the sensor's membrane. The membrane is only a few micrometers thick and deflects depending on the pressure difference existing between its two sides.

For differential sensors, the pyrex™ is drilled with a hole below the membrane (see picture left) so that pressure can be applied on both sides. For absolute sensors, the pyrex™ has no hole and vacuum is created in the cavity underneath the sensor when the pyrex™ is sealed with the silicon. This step is called "Anodic bonding".