Parkhurst & Oliff
Electrochemical NOx sensor
 An NOx sensor for determining the concentration of NOx contained in a measurement gas, having first and second electrochemical detecting elements each of which includes an oxygen pumping cell and an oxygen sensing cell. Each of the pumping and sensing cells of the first and second detecting elements consists of a solid electrolyte and a pair of electrodes. At least one of the electrodes of the oxygen pumping and sensing cells of the second detecting elements which are exposed to the introduced measurement gas, is used as a catalytic electrode which is provided with a catalyst for reducing the nitrogen oxides contained in the measurement gas. The second detecting element detects an oxygen partial pressure of the measurement gas while the nitrogen oxides are reduced by the catalyst of the catalytic electrode. The NOx concentration is determined, based on a difference between two outputs of the first and second detecting elements which represent the oxygen partial pressures of respective portions of the measurement gas detected by the first and second detecting elements. 
NGK Insulators, Ltd.
G G
G01N G01N
inventional inventional
Nobuhide Hiroshi Makoto
Kato Kurachi Noda