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.