Capacitative pressure sensor for oxidative environments

摘要

A capacitative pressure sensor ( 30 ) for harsh environments such as vehicle tires. The sensor has two opposing electrodes ( 36 and 50 ). One electrode is a membrane ( 50 ) that extends between fluid at a reference pressure and fluid at the pressure to be sensed. In use, the flexible membrane ( 50 ) deflects due to pressure differentials between the reference pressure and the fluid pressure. Associated circuitry converts the deflection into a signal indicative of the pressure to be sensed. The membrane is a laminate at least partially formed from a transition metal nitride because transition metal nitrides are a metal ceramics with high yield strength and metallic bonding that makes it suitable for use in extreme environments. They can also readily include an oxidizing component such as aluminium so that the membrane form a passivating surface oxide layer to protect it from oxidative failure.