High Temperature Humidity Sensor Using a Limiting Current Type Plane Oxygen Sensor

A Limiting current type plane oxygen sensor with a unique structure, different from the conventional limiting current type oxygen sensor, has been developed. This sensor has cathode and anode of Pt on the same plane of ZrO2 electrolyte, and the cathode also serves as a hole to limit gas diffusion. An investigation was made to verify the humidity sensing characteristic of this sensor above 100°C. This sensor detects humidity linealy proportional to a water vapor pressure of 0 to 450 mmHg in a wide operation temperature range from 20° to 300°C. No deterioration was observed after 10, 000 h life test.