What is the Difference Between Thermocouple and Thermistor?

The main difference between thermocouples and thermistors lies in their working principles and sensing factors. Here are the key differences between the two:

• Temperature Sensing Parameter: In thermocouples, the variation in temperature creates a voltage between two dissimilar metals, while in thermistors, the resistance changes with temperature variations.
• Material: Thermocouples are made from metal or alloys, while thermistors are made from semiconductor materials or oxides of magnesium, nickel, or cobalt.
• Accuracy: Thermocouples have high accuracy over a wide range of temperatures, including extreme temperatures. In contrast, thermistors have excellent accuracy in mid-range temperature measurement, but their accuracy falls abruptly above or below this range.
• Sensitivity: Thermistors are very sensitive due to their non-linear characteristic curve, providing a high level of sensitivity. Thermocouples are less sensitive compared to thermistors.
• Linearity: Thermistors have a non-linear response, while thermocouples have a mostly linear response to temperature changes.
• Power Source: Thermistors are passive sensors that require a power source to convert their resistance into an electrical signal. Thermocouples are active sensors that do not require a power source.

When choosing between a thermistor and a thermocouple as a temperature sensor, factors such as temperature range, stability, accuracy, and application should be considered.

Comparative Table: Thermocouple vs Thermistor

Here is a table comparing the differences between thermocouples and thermistors:

Both thermistors and thermocouples are suitable for different temperature sensing applications, and the choice between them depends on factors such as accuracy, response time, and the specific application.