MEMS based thermopile infrared sensor technology helps prevent and control the epidemic
Scheme details
Programme background
Novel coronavirus infection is a very common disease in 2020. People from all walks of life pay homage to the heroes who are fighting on the front line and contribute to the Anti Japanese war in various ways.
The novel coronavirus infection in Xinxian County, Xinyang Province, is closely related to the situation in Henan Province, which is close to Hubei Wuhan. The epidemic prevention and control materials are seriously lacking in the county, and the pressure of prevention and control is doubled. In February 3rd, novel coronavirus Group donated $1 million yuan to the Xinxian County Red Cross Society in Xinyang, which is specially used to purchase new coronavirus pneumonia needed medical supplies in the region and meet some emergency cash needs in the region. It is a modest contribution to resolutely win the battle against epidemic prevention and control in Xinxian County.
In the process of novel coronavirus control, ventilator, monitor, oxygen generator, negative pressure ambulance and other medical products played a major role. These do not leave the support of sensor technology. Next, the author will focus on the principle of infrared thermopile sensor and its key application in this outbreak.
Product overview
As long as the temperature of any object in the universe is higher than absolute zero, it will radiate energy at a certain wavelength - that is, infrared radiation. Therefore, under the natural temperature, all objects are emission sources of infrared radiation, but the infrared wavelength of infrared radiation is different. For example, the human body temperature is 37 ?, the infrared radiation wavelength is 9-10 � m; the infrared radiation wavelength of 400-700 ? objects is 3-5 � M.
Infrared is also part of the solar spectrum, an invisible light. Like all electromagnetic waves, it has the properties of reflection, refraction, scattering, interference, absorption, etc. The propagation speed of infrared light in vacuum is 3 � 108m / s, which will cause attenuation in the medium, especially in the metal. But infrared radiation can pass through most semiconductors and some plastics, and most liquids absorb infrared radiation very much.
By using the characteristics of infrared radiation and various characteristics in the process of propagation, using infrared detector to perceive the spectral characteristics of physical processes such as infrared radiation or absorption of objects, we can measure different attributes and characteristics of objects, such as object temperature, which is called infrared measurement technology. The non-contact temperature sensor is made of the principle that the radiant energy of the object changes with the temperature.
According to the working principle, infrared detector can be divided into two categories: thermal detector and photon detector. Among them, the thermal detector is mainly divided into three types: thermocouple / thermopile, bolometers and pyroelectric; the photon detector is mainly divided into intrinsic, extrinsic, free carriers and quantum wells.
In the most widely used field of infrared detector temperature measurement application, thermocouple / thermopile detector based on thermoelectric effect (or Seebeck effect) can be used to realize temperature measurement. The temperature measurement principle of thermocouple is: if two different materials or objects a and B with the same material and different work escaping are connected at the hot end (hot junction area), and open at the cold end (cold junction area), the temperature difference between the hot end and the cold end is ? THC, then a thermoelectric potential Vout will be generated at the cold end. The temperature measurement can be realized by measuring the thermoelectromotive force.
Schematic diagram of thermoelectric effect
Thermopile is composed of many pairs of thermocouples in series, which has a larger output thermal potential than a single thermocouple. As a kind of non-contact infrared temperature sensor, thermopile can quickly measure the surface temperature of the object without directly contacting the measured object. It can measure the high temperature, dangerous or moving object, and it will not pollute or damage the measured object.
The electronic thermometer is a thermopile type infrared sensor, which converts the infrared radiation of human body into the change of electrical signal, so as to display the temperature of human body. Compared with the traditional mercury thermometer, the electronic thermometer has the advantages of safety, direct reading, short time and high precision.
Mrt117 thermopile temperature sensor (to-46 package)
Mrt311 thermopile temperature sensor (to-46 package)
Sensor features:
To-46 package, high sensitivity, fast response, good stability, high filter transmittance, high NTC precision.
Main applications:
? non contact temperature measurement;
? non contact measurement of infrared body temperature such as ear temperature and frontal temperature;
? continuous temperature control in the production process;
? temperature measurement and control of household appliances (microwave oven, hair dryer, air conditioner, etc.);
? human presence detection
The higher the temperature of the object, the greater the infrared radiation intensity. The thermopile infrared detector based on MEMS technology can measure the temperature by detecting the infrared radiation of the object at a certain distance. The sensing element of thermopile detector consists of several micro thermocouples on silicon substrate, which can absorb radiation energy and generate output signals.
The difference between thermopile sensor and pyroelectric sensor: it can detect both dynamic signal and static signal, and the temperature can be measured accurately. Thermopile infrared detector can be equipped with various lenses and filters, so as to realize the application in various application scenarios such as temperature measurement, qualitative / quantitative analysis of gas composition, medical equipment, etc.
At present, it has been widely used in the fields of frontal temperature gun, ear temperature gun, intelligent home appliances, lamp switch, food temperature detection and so on.
Write at the end
Despite the current epidemic situation |
