Parkhurst, Oliff & Berridge
Oxygen sensor
 An oxygen sensor element includes at least a standard electrode (i.e., reference electrode) and a measurement electrode and is made of an oxygen ion-conducting solid electrolyte and is accommodated in a casing. An airtight space formed in the oxygen sensor element or in the casing communicates with the standard electrode and is maintained substantially in an airtight state with respect to the external atmosphere. At least one pair of oxygen pump electrodes for supplying oxygen to the airtight space is arranged in the oxygen sensor element. Therefore, since it is not necessary to arrange a hole for the supply of a reference substance (such as air) in the oxygen sensor, it is possible to completely eliminate the deterioration and the damage of the oxygen sensor element due to the intrusion of water, sea water and the like from the external atmosphere. 
NGK Insulators, Ltd.
G G
G01N G01N
inventional inventional
Nobuhide Atsushi
Kato Iino