Ceramic Moisture Sensor Basics
Ionic humidity sensor is formed by a porous ceramic insulating material components. As the water molecules in the pores of the physical adsorption, the air present in the wet H +, increase the conductivity of the element, mainly two types of α-Fe2O3 component and K2CO3 and ZnO.V2O5.LI2O.
Ceramic humidity sensor resistance at low humidity segment larger resistance change with humidity at 40% -80% RH range, good linearity, high humidity segment the change is too small, visible ceramic humidity sensor in the normally wet state with good the characteristic curve segment in the high humidity, low humidity curve in distortion, nonlinear obvious. German ceramic humidity sensor sensing property also affected by temperature changes, temperature compensation of the measurement accuracy is important.
E-humidity sensor are alumina, a synthetic magnesium oxide ceramic humidity sensor element increases and decreases the conductivity, the surface of the oxide molecular chemisorption formed, N-type semiconductors, P-type semiconductor oxide to a positive humidity, moisture characteristics and negative characteristics.
Alumina, magnesia, and a humidity sensor, the temperature at below 700 ℃ moisture measurements can be made more stable. But the structure is complex and requires heating the grating is heated to 700 ℃, power-intensive use of harsh conditions, the price is expensive, but also to prevent changes in air flow characteristics cited changes, not universal use in the industrial field.
Ceramic humidity sensor in recent years to develop a new type of sensors. Advantages humidity lag, fast response, small size, easy to mass production, but because of porous material, a great impact on the dust, routine maintenance frequently, often need to be cleaned easily electrically heated affect product quality, affected by humidity, the humidity Linear temperature environment is poor, especially short life, long-term reliability is poor, the humidity sensor is such an urgent problem
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