Ceramic Humidity Sensors

A novel humidity sensor using a MgCr204-TiO2 porous ceramic has been developed for an automatic microwave oven. Physical properties of the MgCr204-TiO2 ceramic, construction and humidity characteristics of the sensors, and outlines of the control of the automatic microwave oven by humidity sensing are described. The MgCr204-TiO2 ceramic exhibits a typical porous structure and semiconduction. The porous ceramic easily absorbs water vapor throughout the pores. The ceramic grain surfaces behave like electrolytes. The ceramic humidity sensor utilizing its humidity sensitive effects and rejuvenating response to heat treatment exhibits high humidity and long term stability. The novel humidity sensor has been applied in many processes such as microwave ovens, air conditioners, dryers, etc.