Parkhurst, Oliff & Berridge
Electrochemical gas sensor
 An electrochemical device for detecting a measurement fluid, which includes a planar solid electrolyte body, a first electrode formed on the planar solid electrolyte body and substantially exposed to the measurement fluid, a second electrode formed on the planar solid electrolyte body and substantially isolated from the measurement fluid, a porous layer disposed in direct contact with the second electrode, and a device for applying an electric current so as to flow from the second electrode to the first electrode. The device may further include a third electrode, and a fourth electrode substantially directly exposed to the measurement fluid. In this case, the first and third electrodes are exposed to the measurement fluid through a thin flat space or porous layer having a predetermined diffusion resistance to the measurement fluid, and a current regulating device is connected between the third and fourth electrodes, for controlling an atmosphere adjacent to the first electrode. 
NGK Insulators, Ltd.
G G
G01N G01N
inventional inventional
Atsushi Nobuhide
Iino Kato