US Patent 7150195 Sealed capacitive sensor for physical measurements

A capacitive-type sensor comprises a glass plate having an electrode formed thereon, and a micromachined structure formed from a semiconductor material and having an insulating rim formed thereon. A conducting seal is formed on the insulating rim and arranged to be bonded to the glass substrate to define an enclosed cavity containing the electrode, to thereby define a capacitive element, the conducting seal being arranged, in use, to have an electrical signal passed there through to determine a capacitance thereof which is indicative of the parameter to be determined by the sensor.