Humidity sensor

A moisture sensor is a measuring probe for determining the water content of a substance or test volume. Since the measurement of humidity is necessary in a wide variety of applications, numerous technical implementations of different measuring principles exist side by side.

Applications

Humidity sensors are used, for example, in meteorology in hygrometers to measure air humidity . In agriculture, moisture sensors are used to measure soil moisture in tensiometers . In cosmetics and dermatology , corneometers are used to measure skin moisture in the upper layers of the skin. Microwave-based methods are used to measure the moisture in bulk solids.

Physical measuring principles

Because of the very different fields of application for humidity sensors, numerous measuring principles are also used. The following list gives an incomplete overview of some of the underlying physical principles:

Surname	Physical principle	Application example
Microwave absorption	Electromagnetic wave absorption	Bulk goods
capacitive measurement	Change in the dielectric constant	skin
electric conductivity	Change in electrical conductivity or specific resistance	Soil moisture
Weigh	Determination of the water content by drying ( kiln ) and weighing	Wood moisture

The additional measuring methods for moisture measurement shown in italics are manual methods that cannot be used in sensors.