A temperature sensor refers to a sensor that can sense temperature and convert it into a usable output signal. The temperature sensor is the core part of the temperature measuring instrument, and there are many varieties. According to the measurement method, it can be divided into two types: contact type and non-contact type.
According to the characteristics of sensor materials and electronic components, it is divided into two types: thermal resistance and thermocouple.
Thermocouple is the most commonly used temperature sensor in temperature measurement. The main advantage is that it has a wide temperature range and adapts to various atmospheric environments, and it is sturdy, low-cost, and does not require power supply. The thermocouple is composed of two different metal wires (metal A and metal B) connected at one end. When the thermocouple is heated at one end, there is a potential difference in the thermocouple circuit. The measured potential difference can be used to calculate the temperature.
In short, the thermocouple is the simplest and most versatile temperature sensor, but the thermocouple is not suitable for high-precision measurement and application.
Thermistors are made of semiconductor materials, most of which have a negative temperature coefficient, that is, the resistance decreases with increasing temperature. Temperature changes will cause large resistance changes, so it is the most sensitive temperature sensor.
Thermistors also have their own measurement techniques. The thermistor's small size is an advantage, it can be quickly stabilized without causing thermal load. However, it is also not very strong, and large currents will cause self-heating. Because the thermistor is a resistive device, any current source will cause heat on it due to power. The power is equal to the product of the current squared and the resistance. Therefore, use a small current source. If the thermistor is exposed to high heat, it will cause permanent damage.