How is the STORK Bi-Ceramic sensor different from sensors made by our competitors?
For many years impedance humidity sensors have employed either aluminum oxide or polymers to create the active impedance layers. Polymers do not provide the necessary sensitivity to make them suitable for low level humidity measurements.
Sensors in which the response layer is made from aluminum oxide (sometimes called ceramic sensors), are made by anodizing aluminum. A thinner layer than this cannot be made using this process without reducing the thickness of the electrical barrier layer to a level which risks electrical short circuits during the sensor’s operation. The thick response layer is therefore a factor limiting performance in sensors produced by rival manufacturers. It means that response time, particularly in the low humidity regions is very long.
A second disadvantage of this type of sensor is that aluminum oxide undergoes a slow conversion process over time to aluminum hydroxide and this manifests itself as calibration drift, which means that this type of sensor requires re-calibration at frequent intervals.