What are the characteristics of temperature sensors?

Temperature sensors are devices that detect temperature and are widely used in fields such as industrial and agricultural production, scientific research, and daily life. They have a wide range of types and are developing rapidly. Temperature sensors are generally divided into two categories: contact type and non-contact type. The so-called contact type refers to the sensor directly contacting the measured object for temperature measurement, which is the basic form of temperature measurement. Non contact type refers to the measurement of the infrared radiation emitted by the object to measure the temperature of the object, Telemetry can be performed, which cannot be achieved by contact methods. Contact temperature sensors include thermocouples, thermistors, platinum resistors, etc. They use the characteristics of the thermoelectric electromotive force or resistance generated by them to measure the temperature of objects with temperature changes. They are widely used in household appliances, automobiles, ships, control equipment, industrial measurement, communication equipment, etc.
In addition, there are some newly developed sensors, such as semiconductor integrated sensors that utilize the temperature dependent current/voltage characteristics of semiconductor PN junctions; Fiber optic sensors that utilize the propagation characteristics of optical fibers to vary with temperature or semiconductors; Sensors that utilize the oscillation frequency of elastic surface waves and oscillators to vary with temperature; NQR sensors that utilize temperature dependent oscillation frequencies of nuclear quadruple resonance; There are magnetic temperature sensors that utilize sharp magnetic changes near the Curie temperature, as well as sensors that use liquid crystals or paint colors to change with temperature. Non contact methods measure the temperature of objects by detecting infrared radiation in light sensors. There are quantum type sensors that use semiconductors to absorb light and cause electron migration, and thermal type sensors that absorb light and cause temperature changes. Non contact sensors are widely used in contact temperature sensors Radiation thermometer, alarm device, guest notification device, fire alarm, automatic door, gas analyzer, spectrophotometer, resource detection, etc