Bimetallic strips and thermistors are two commonly used temperature sensing elements, and they differ in their operating principles and advantages:

Bimetallic Strips

Operating Principle:

Bimetallic strips are typically made by laminating two or more metals with different coefficients of expansion.

When the temperature rises, the different metals expand at different rates, causing the bimetallic strip to bend.

This bending can trigger a mechanical switch, such as breaking a circuit or activating an alarm.

Advantages:

Simple and Reliable: The structure is simple, without complex electronic components, making it more durable and less susceptible to electromagnetic interference.

Low Cost: The manufacturing cost is relatively low, suitable for cost-sensitive applications.

No Power Required: Operation does not require an external power source, providing protection even in the event of a power outage.

Intuitive Response: The physical bending caused by temperature changes can intuitively display temperature variations.

Thermistors

Operating Principle:

A thermistor is a semiconductor material whose resistance value changes with temperature.

There are typically two types: Negative Temperature Coefficient (NTC) thermistors, which decrease in resistance as temperature rises; and Positive Temperature Coefficient (PTC) thermistors, which increase in resistance as temperature rises.

By measuring the change in the resistance value of the thermistor, the temperature can be calculated.

Advantages:

High Precision: Can provide very accurate temperature measurements, suitable for applications that require precise control.

High Sensitivity: Responds quickly to temperature changes, allowing for rapid detection of temperature variations.

Programmable: Can be programmed through electronic circuits to achieve more complex temperature control logic.

Miniaturization: Thermistors are small in size and easy to integrate into various devices.

Remote Monitoring: Electronic signals can be used for remote temperature monitoring, suitable for remote monitoring systems.

Bimetallic strips are more suitable for simple, cost-sensitive applications with low precision requirements, such as basic overheating protection. Thermistors are suitable for complex temperature control applications that require high precision and rapid response, such as temperature monitoring and control systems for precision instruments. The choice between these types of sensors depends on the specific needs and budget of the application.