Humidity determination by solid state limiting current sensor

The behaviour of a pinhole type sensor for the determination of humidity (1 000-28 000 ppm of water vapour, corresponding to about 3.5 to 90 RH% at 25 degrees C) in N-2 and in N-2/O gas mixtures is presented. The operating tem perature of the sensor, consisting of a zirconia-based electrochemical cell with a diameter and a thickness of 10 and 5 mm, is 500 degrees C. Imposing a ser of potential (from 0 to 1400 mV) to the electrodes, typical polarogr aphic curves were observed, in the presence of two electroactive species tw o limiting curves were obtained. Water vapour concentration can be obtained with an error not exceeding +/-4%. (C) 1999 Elsevier Science B.V. All righ ts reserved.