Why Thermopile Sensors Are Out Of Stock

Thermocouples are usually connected in series, sometimes in parallel, which is the thermopile. Thermopile cannot measure the absolute temperature, but 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 of a single thermocouple, and the thermocouple temperature sensor made with it has high temperature measurement sensitivity.

In practical applications, the high-temperature thermistor is used to measure the ambient temperature of the thermopile, and then the measured temperature is calculated by the CPU. Some standard temperature conditions can be written in the EEPROM in advance, for example: the output voltage measured under the condition that the temperature of the measured object is 37 ° C and the ambient temperature of the thermopile is 25 ° C. In addition, the output voltage of the thermopile, the bias of the op amp, and the dispersion of the gain can also be corrected by software so that the temperature of the measured object can be measured.

In fact, the red thermopile sensor in our forehead gun is much more complicated. It uses a silicon-based micromachining process. Several thermocouples of the thermopile are arranged on a silicon wafer support layer, and these thermocouples are connected in series. To form a thermopile chip.

The sudden outbreak of new crown pneumonia has negatively affected the growth of several global industrial chains. However, the epidemic situation has also made the thermopile sensors of epidemic prevention materials with stable demand usually a sudden commodity.

Detailed explanation of infrared thermopile sensor

As long as any object is above absolute zero, it will radiate energy at a certain wavelength, but the radiant energy in the low temperature section is very weak.

At normal temperature, all objects in nature are the source of infrared radiation, but the wavelength of infrared radiation is different. For example, the temperature of a human body is 37 ° C, and the infrared radiation wavelength is 9-10 μm; the infrared radiation wavelength of an object at 400-700 ° C is 3-5 μm.

The non-contact temperature measurement sensor is made by using the principle that the radiant energy of an object changes with temperature.

The infrared thermopile sensor converts the absorbed infrared radiation into thermal energy, and converts the temperature change into an electronic signal, which is displayed enlarged.

As a non-contact infrared temperature sensor, the thermopile can quickly measure the surface temperature of the object without directly contacting the measured object. It can measure high-temperature, dangerous or moving objects without contaminating or damaging the measured object.

At present, it has been widely used in the fields of forehead thermometer, ear thermometer, smart home appliances, lighting switches, food temperature detection and other fields.

According to the Minamata Convention on Mercury, signed by a representative of the government of the People's Republic of China in Kumamoto in 2013, since 2020, each contracting country has banned the production and import and export of mercury-containing products. Therefore, electronic thermometers will replace mercury thermometers and become a necessary amount for households Thermo gun, ear thermometer.

The electronic thermometer uses a thermopile infrared sensor to convert the infrared radiation radiated from the human body into changes in electrical signals, thereby displaying the temperature of the human body. Compared with traditional mercury thermometers, electronic thermometers have the advantages of more safety, intuitive readings, short time, and high accuracy.

The thermopile is based on the Seebeck effect mechanism. Two materials with different Seebeck coefficients are connected in series to form a closed-loop circuit (ie, a pair of thermocouples). The higher temperature end of the two series is usually called the "thermal junction" ", The lower end is called" cold junction ". The carriers in the material move along the direction of the temperature gradient decrease, causing charges to accumulate at the cold junction. At this time, a thermoelectric potential is generated in the circuit.

The thermopile is based on the Seebeck effect mechanism and adopts silicon-based micromachining technology. Several thermocouples of the thermopile are arranged on the silicon wafer support layer, and these thermocouples are connected in series to form a thermopile chip. When the sensor receives infrared radiation, the voltages of the thermocouples on the hotspot chip are superimposed and output, thereby converting the test temperature into a voltage signal.