Solid-State NO Sensor for Medical Use Based on Proton Conductor (Antimonic Acid) Operative at Room Temperature

Solid-state electrochemical devices using proton-conductive antimonic-acid were examined for detecting small amounts of NO in wet air at room temperature. Two types of sensor devices were fabricated by using a disc or a thick film of antimonic acid. As a sensor signal, the electric current through the proton conductor was measured under the condition in which the constant voltage was applied between the sensing and the reference electrodes by means of a potentiostat. The current response of the sensor was found to be almost linear to NO concentration in the range of 0-100 ppm. In addition, by selecting the applied voltage, it was possible to differentiate NO and NO2 selectively. A small planar-type device using the thick film was also found to give fairly good sensing properties to NO. The NOx sensing mechanism of the present sensor was briefly discussed.