Definition | Humidity sensor – Humidity sensor

The sensor humidity allows, as its name suggests, to measure the ambient humidity. A useful measure in matter of meteorology, but also in the housing sector. Indeed, thehumidity in a house can be problematic. A air too humid, or too dry, can be a source of inconvenience, or even cause sanitary risks.

Capacitive and resistive humidity sensors

There are humidity sensors (or hygrometers) Capacitive and resistive humidity probes (or hygrometers).

A capacitive probe plays on the relative humidity sensitivity of the ambient air of the constant dielectric of materials such asalumina – or thealuminum oxide – or sometimes from polymers. At the heart of the system therefore, a capacitor whose capacity varies according to humidity. The sensitivity of this type of instrument is around 3% and its measurement range is wide.

A resistive sensor, meanwhile, plays on the humidity sensitivity of the resistivity of certain materials, chloride of lithium for example. The latter presents, in fact, a resistance high when dry and low resistance when wet. The problem is that this type of probe only works over a reduced humidity range. Also pay attention to the resistance of materials which can also vary with temperature.