The FK120J series is a line of capacitive relative humidity sensors manufactured by Galltec. It measures air humidity using a humidity-dependent condenser.
The device was designed based on thin-film technology. It is equipped with a base plate in which electrodes are housed, and has a hygroscopic polymer layer on top. The layer absorbs water molecules from the measuring medium, or releases them by changing the capacity of the condenser. The change in capacity is processed through integrated signal preprocessing into standardized signals, with a voltage rating of 0 to 10V DC, and a current rating of 0/4 to 20 mA.