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Humidity Sensor Working Principle

 Impedance type Humidity Sensor: Accurate, fast and reliable ceramic moisture sensor for the measurement of absolute humidity in process air and gases


The principle of operation is quite simple. Operation of the sensor depends upon the adsorption of water vapour into a porous non-conducting “sandwich” between two conductive layers built on top of a base ceramic substrate. The active sensor layer is very thin – less than one micron (a millionth of a metre) and the porous top conductor that allows transmission of water vapour into the sensor is less than 0.1 micron thick. Therefore the sensor responds very rapidly to changes in applied moisture, both when being dried (on process start-up) and when called into action if there is moisture ingress into a process.


The resistance or impedance of the sensor ceramic layers changes with the water vapour applied to it. Finally converting the change in impedance will give us the humidity value.


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  1. UbiBotApril 12, 2021 at 1:08 AM

    Thanks for this wonderful and detailed information about the working principle of the humidity sensor. As I read the whole article and will say one thing the author describes the working principle of the humidity sensorin a very simple way that anyone can understand very quickly. It really helps those who want to learn about humidity sensors.

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