:: IPCI ::

Pressure difference between two faces of the membrane
will cause the distance change between the ring and the pedestal
This causes the change of ring-to-pedestal capacitance
which is the input capacitance of an FET built into the silicon membrane

Useful operating range of the device is extended beyond the full-scale deflection
that is conventionally defined by the point where DC = C
Electrode must be electrically isolated from the membrane,
such as by an intervening thin film of dielectric material
Capacitance keeps raising even beyond the threshold at which the diaphragm touches
the substrate beneath it