Solid electrolyte gas-sensor without ionic transfer - uses minority carrier transport to make it free of surface polarisation and able to operate at low temperature

摘要

The gas sensor, used to measure the gas partial pressure, consists of a solid electrolyte (1) with ions as majority charge carriers to which 2 electrodes have been attached. The feature is that inert electrode (5) is hermetic and in addition its edges have been sealed against the electrolyte surface to avoid a stationary movement of the ionic majority carriers. Electrode (3) is porous and allows the gas to come into contact with the electrolyte. The polarity and height of the DC bias is chosen to avoid a stationary ion-current in the electrolyte. Also claimed is a sensor in which a hermetically sealing covering is formed over one electrode (5). The electrolyte is pref. a flat plate of layer and the electrodes are pref. on opposite sides of this layer. The electrolyte is pref. a material which contains mobile ions of the gas to be measured, i.e. cubic or tetragonal ZrO2 or CeO2 with the hermetic electrode (5) biased negatively for oxygen pressure sensing. USE/ADVANTAGE - The cell formed shows a DC current which is carried only by the minority carriers, which means there is not transfer of ions from the gas to the electrolyte in the stationary condition. This avoids the occurrence of polarisation effects.