A temperature sensor is a device used for measuring temperature. A typical atmospheric temperature sensor uses a resistance temperature detector (RTD) element for measuring temperature. The RTD element is made by wrapping a fine wire around a ceramic or glass core. Generally, the wire is made of copper, nickel, or platinum. These sensors are highly reliable and accurate in measuring temperature changes. They are ideal for use in applications that require precise tracking of temperature changes. The different types of atmospheric temperature sensors and their working principle are as follows:
Types of Atmospheric Temperature Sensors
The different types of atmospheric sensors are as follows:
Negative Temperature Coefficient (NTC) Thermistor
A thermistor is a device that is sensitive to a large and variable change in resistance due to a change in temperature. They are generally made of nickel or any ceramic type material. An NTC thermistor has a very high resistance at low temperatures. The resistance drops sharply with an increase in the temperature. Since the NTC thermistor is highly sensitive to temperature changes, they measure small changes in temperature very accurately (within 0.5-1.5-degrees Celsius). As it is exponential, the output of NTC thermistors needs linearization.
Resistance Temperature Detector (RTD)
An RTD is also known as a resistance thermometer. It measures temperature by correlating the resistance of the RTD element with temperature. These temperature sensors have a film, or a wire wrapped around a ceramic or glass core, for greater accuracy. Generally, RTDs are made of nickel or copper. Some RTDs are also made of platinum for measuring temperature more accurately. Platinum RTDs provide a linear output with a high degree of accuracy (0.1-1-degrees Celsius) across -200 to 600 degrees Celsius. Though RTDs are very reliable and accurate, they are also the costliest of all atmospheric temperature sensors.
These are the most common and cost-effective temperature sensors. The voltage changes are changed by varying temperature. A thermocouple consists of two wires of different metals connected at two points. The varying voltage between these two points is proportional to the changes in temperature. The accuracy of these temperature sensors is low. They are nonlinear and require conversion when used for temperature control and compensation.
These sensors use two identical diodes with a temperature-sensitive voltage that can be used for measuring temperature changes. They provide a linear response but have the lowest accuracy among all temperature sensors.