Development of temperature and humidity sensors
As early as 1593, Galileo, an Italian scientist, invented a thermometer for people to measure temperature.
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It was not until 1821 that Seebeck, a German physicist, discovered the Seebeck effect of turning temperature into electrical signals and made thermocouple sensors to measure temperature. This discovery left an indelible contribution to the industrial revolution.
In the early stage, due to the limitation of technology, the sensor can not measure temperature and humidity at the same time, so in order to measure the two important parameters of temperature and humidity, we have to use temperature sensor and humidity sensor at the same time.
Wall mounted digital tube King shell temperature and humidity sensor
The earliest invention of human is the thermometer, and the principle of thermometer is to use the thermal expansion of liquid, the height of the liquid column corresponds to the temperature scale to measure the current temperature. The disadvantages of this thermometer are limited range and limited precision. The humidity sensor is made of simple humidity sensitive resistance (capacitance). The principle of humidity sensor and humidity sensitive capacitance is that the humidity sensor is covered with a layer of polymer film, which will affect the conductivity value of resistance or capacitance value with the change of humidity. Using this characteristic, the humidity sensor can complete the measurement of environmental humidity.
Since then, with the development of science and technology, people have developed a variety of temperature and humidity sensors. In this century, with the support of semiconductor technology, semiconductor thermocouple sensor, PN junction temperature sensor and integrated temperature sensor have been born one after another. Accordingly, acoustic temperature sensors, infrared sensors and microwave sensors have been developed according to the interaction between wave and matter.