Temperature sensors can be used in a wide variety of applications and therefore, there are many different kinds of temperature sensor technologies to select from for the given application. The most common ones are thermistors which are divided into two groups: NTC and PTC. For NTCs (Negative Temperature Coefficient) the resistance of the sensing element drops the hotter it gets. For PTCs (Positive Temperature Coefficient) it is the reverse, as the sensing element gets hotter, the resistance of the element increases.

RTDs (Resistance Temperature Detectors) are similar to thermistors, but their sensing element is a platinum wire. RTDs also change their resistance when their temperature changes but unlike the thermistor it is not a curve but a linear relationship. For the contactless measurement of temperature , thermopiles are used, which are based on the infrared radiation of a target object or human being. Their big advantage in comparison with pyroelectric sensor is that they can even sense a non-moving target.

For applications where you do not need specific temperature measurement but need to switch something ‘On’ or ‘Off’ at a defined temperature, thermostats are the best option. These devices consist of a bi-metal strip that opens or closes its contacts at a defined temperature.