Whether at the workplace, in residential buildings or in production processes: Temperature is measured and controlled everywhere. But why is the measurement of temperature so important? In relation to people, temperature is an important factor influencing their comfort. In building technology, comfort defines a climatic condition range in which room users feel comfortable. Depending on relative humidity, the comfortable temperature range lies between 18°C and 24°C. Since people perceive temperatures subjectively differently, an objective measurement of this variable is necessary in order to regulate the ventilation and air-conditioning systems according to requirements. Another important reason for measuring temperatures is that different substances behave differently at different temperatures. Depending on the application, an individual process temperature is required, e.g. in clean rooms, greenhouses or production halls.

Temperatures are measured, for example, in building automation, clean room technology or industrial applications. In the field of ventilation technology, temperature measurements are used to control the room air temperature. Temperature values can be recorded in the duct, for example for supply air, or in rooms, such as industrial halls or office buildings. For clean rooms, laboratories or operating theaters, critical temperature ranges are defined that must be permanently maintained to ensure process reliability. Measuring systems are used to record the temperatures, monitor compliance with the critical temperature range and transmit the data to higher-level systems. Thus, the measurement data can be logged or alarms can be triggered when limit values are exceeded or not reached.

Temperature measuring systems from FSM are based on a capacitive measuring principle. The sensor element consists of a capacitor whose dielectric consists of a polymer. This absorbs or releases water in proportion to the relative ambient humidity. The resulting change in the dielectric constant alters the capacitance of the capacitor, which can be measured with an electronic circuit. The temperature measurement is made possible by bipolar transistors.