A Novel Humidity Sensor using Yb-Doped SrCeO3 Ionic Conductor with a Au-Pd Filter

A novel humidity sensor operating at T<580K using Yb-doped SrCeO(3) ionic conductor with a Au-Pd chemical filter has been developed. In this unique design, both the electrodes are exposed to the same test gas and therefore do not require separation of working and reference compartments. A thin layer of impervious Au-Pd alloy on one surface of the perovskite electrolyte allows selective access to oxygen gas, while the other surface coated with porous Pt is exposed to both H(2)O and oxygen. Sensor emfs are found to be directly proportional to log pH(2)O and independent of pO(2). The design aspects of the sensor, the experimental set-up, some typical results and a postulated mechanism of sensor operation are described in this paper.