What are the commonly used temperature sensors?

2022-07-06 09:48

(1) NTC thermistor and its temperature sensor: The negative temperature coefficient thermistor has (NTC) negative temperature coefficient characteristics, the temperature rises, the resistance value decreases, and the resistance value corresponds to the temperature one by one. Changes in temperature can be known. Among all passive temperature sensors, the thermistor has the highest sensitivity (that is, the change in resistance when the temperature changes by one degree), and a small temperature change will cause a large change in resistance value, but the resistance/temperature curve of the thermistor is the highest. is nonlinear.

 

(2) Resistance temperature detector: A resistance temperature detector (RTD) is actually a special wire whose resistance changes with temperature. Usually RTD materials include copper, platinum, nickel and nickel/iron alloys. The RTD element can be a wire or a thin film, which is coated on a ceramic substrate by electroplating or sputtering.

 

(3) Thermocouple sensor: A thermocouple is a temperature sensing element and an instrument. It directly measures the temperature, and converts the temperature signal into a thermoelectromotive force signal, which is converted into the temperature of the measured medium through an electrical instrument (secondary instrument). The basic principle of thermocouple temperature measurement is a closed loop composed of two different material conductors. When there is a temperature gradient at both ends, a current will flow through the loop. This is the so-called Seebeck effect.

 

(4) Digital output sensor: The digital temperature sensor was introduced in the mid-1990s. It is the crystallization of microelectronic technology, computer technology and automatic test technology (ATE). At present, a variety of intelligent temperature sensor series products have been developed internationally. The intelligent temperature sensor contains temperature sensor, A/D converter, signal processor, memory (or register) and interface circuit. Some products also have multiplexers, central controller (CPU), random access memory (RAM) and read only memory (ROM). The characteristic of intelligent temperature sensor is that it can output temperature data and related temperature control quantity, and adapt to various microcontrollers (MCU); and it realizes the test function through software on the basis of hardware.

 

(5) Analog integrated temperature sensor: The integrated sensor is made by silicon semiconductor integration process, so it is also called silicon sensor or monolithic integrated temperature sensor. The analog integrated temperature sensor was introduced in the 1980s. It is a special IC that integrates the temperature sensor on a chip and can complete the functions of temperature measurement and analog signal output. The main features of the analog integrated temperature sensor are single function (only temperature measurement), small temperature measurement error, low price, fast response speed, long transmission distance, small size, micro power consumption, etc. Non-linear calibration is required, and the peripheral circuit is simple.

 

(6) Semiconductor sensors: Semiconductor sensors are devices that appear in the form of ICs. Typically, these sensors are called IC temperature sensors. Current output temperature sensor, resistor output temperature sensor, resistor output silicon temperature sensor, diode temperature sensor, digital output temperature sensor. Current semiconductor temperature sensors offer high linearity and high accuracy over an operating range of approximately 55°C to +150°C.

 

(7) Infrared sensor: It is an electronic instrument, and the infrared sensor is a non-contact temperature sensor. They are light-sensitive devices that detect infrared (IR) radiation from surrounding areas or objects to measure heat. These sensors are classified into thermal infrared sensors and quantum infrared sensors.


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