What is a thermopile sensor? To put it simply, the thermocouples are usually connected in series, sometimes it will be in parallel that is thermopile. Thermopiles can't measure the absolute temperature, but it can output a voltage proportional to the temperature difference. For the same temperature difference, the electromotive force in the thermopile is much larger than that produced by a single thermocouple. And the thermocouple thermometer made with it is also highly sensitive.
As long as any object is above absolute zero, it will radiate energy at a certain wavelength, but the radiant energy at low temperature is very weak. In the room temperature, all objects in nature are emission sources of infrared radiation. The only difference is the wavelength of infrared radiation.
The non-contact temperature sensor is made by the principle that the radiant energy of an object changes with temperature.
The infrared thermopile sensor converts the absorbed infrared radiation into heat energy, and transfers the temperature changes into electronic signals, which are amplified and displayed. As a non-contact infrared temperature measurement sensor, the thermopile can quickly measure the surface temperature of the object without directly contact with the object to be measured. It can measure high-temperature, dangerous or moving objects without polluting or damaging the object.
This is the basic principle. In fact, the infrared thermopile sensor in our forehead thermometer is much more complicated. It uses a silicon-based micromachining process to arrange several thermocouples of the thermopile on the silicon support layer. These thermocouples are connected in series to form a thermopile chip.
Any individual with temperature will have infrared radiation. And the radiant power increases as the surface temperature as it increases. Based on this relationship, the thermopile measures the transmit power and determines the temperature of the object accurately.
When the sensor receives infrared radiation, the voltage of each thermocouple on the thermopile chip superimpose and output, thereby converting the test temperature into a voltage signal. The thermopile can measure temperature by detecting infrared (IR) energy of an object at a certain distance. The higher the temperature, the more infrared energy is produced. The thermopile sensing element consists of some small thermocouples on a silicon chip, which can absorb energy and generate an output signal.