What is a Temperature Sensor?

Temperature sensors are a device used in our everyday lives to measure the temperature of the air, a liquid, and solid matter in a wide range of industries and applications.

Temperature sensors are found everywhere. If you have ever received a notification on a hot day that your smartphone has got too hot, that is because they contain an embedded temperature sensor that measures the internal temperature to prevent overheating.

Temperature sensors are not only found in phones, they are useful in a wide range of applications such as household appliances, the food and beverage industry, and geotechnical monitoring, which we will look at later on in this article.

Before we look at the different types of temperature sensors and what applications they are used in, let’s take a look at exactly what a temperature sensor is and how it functions.

What Is A Temperature Sensor?

A temperature sensor is a device used to measure the temperature (hotness or coolness) of the air, a liquid, or solid matter.

Temperature sensors work by providing a readable temperature measurement via electrical signals inside the probe or device. They contain two metals that generate an electrical voltage or resistance across the diode terminals when a temperature change occurs.

If there is a voltage increase, the temperature also rises, shortly followed by a voltage drop between the terminals and emitter in the diode.

What Are The Different Temperature Sensors?

There are different temperature sensors available, below are the most commonly used:

Thermistors
Thermocouples
RTDs (Resistance Temperature Detectors)

Temperature sensors work differently, some require direct contact (contact sensors), while others indirectly measure temperature (non-contact temperature sensors).

Non-contact temperature sensors measure how hot or cold something is via infrared (IR) sensors and are widely used in food production and hazardous environments such as power plant industries.

The most basic contact temperature sensor is a thermometer, which comes in two types: bi-metal thermometers and gas-filled and liquid thermometers. Even though thermometers are an easy way to measure temperatures, with advances in technology, thermocouple, thermistor, and RTD temperature sensors are more commonly used.

Thermistors

Also known as thermally sensitive resistors, thermistors change their physical appearance when a change in temperature is detected. Thermistors contain ceramic materials such as nickel, manganese, or cobalt that allow them to easily be disfigured.

Most thermistors have a negative temperature coefficient (NTC) which means their resistance decreases when an increase in temperature occurs. Some thermistor temperature sensors have a positive temperature coefficient (PTC), therefore when the temperature rises, the resistance also increases.

Thermocouples

Thermocouple temperature sensors are commonly used due to their reliability, accuracy, sensitivity, simplicity, and wide temperature operating range. They have two wires that contain two dissimilar metals that connect at two different points to form a junction. It is the voltage between the two wires that measures the temperature change.

Thermocouples may not be as accurate as RTDs; however, they are more affordable and have an extensive temperature range of -200 °C – 1750 °C.

Thermocouples are commonly used in industrial applications, ovens, and gas-powered boilers.

RTDs

Resistive temperature detectors (RTDs) are a type of temperature sensor that gives very precise measurements. They are made from high-purity conducting metals such as platinum, copper, or nickel, that are wound into a coil. Their electrical resistance works similarly to a thermistor temperature sensor.

They are used in industrial applications where reliability and accuracy are essential in temperature monitoring.

What Is The Most Accurate Temperature Sensor?

An RTD temperature sensor is the most accurate and stable device for measuring temperature in a wide range of applications, which is why at Atlas Scientific we offer high purity platinum RTD temperature probes to always give you low latency and highly accurate readings.

It is the platinum metal in Platinum RTD sensors that provide accurate and precise temperature measurements while maintaining high-temperature capabilities. Platinum RTD temperature sensors are used in industrial applications and laboratories worldwide, giving them a reputation for high accuracy and stability. Because of this, platinum RTD sensors are the “industrial standard” when it comes to selecting temperature sensors.

What Applications Use Temperature Sensors?

Temperature sensors are extremely useful to cater to both commercial and consumer needs, which is why they are used in a wide range of industries and applications. Some examples are:

Industrial Applications: Environments in industrial applications can be very demanding, therefore, temperature sensors are most commonly used to control the heat in electrical radiators.
Medical Applications: Used to monitor critical temperature measurements in patients. They can also be found in MRI imaging machines and portable ultrasound scanners to monitor the cryogenic cooling of superconducting electromagnets.
Laboratory Applications: Often used in the pharmaceutical industry for sanitary reasons and to control the environmental temperature in laboratories.
Household Appliances: In refrigerators and freezers, temperature sensors are used to measure the cooling chamber, create ice cubes, and prevent excessive ice build-up. In microwaves and ovens, temperature sensors are used for heating control.
Computers: Temperature sensors are used to prevent computers from overheating.
Food & Beverage Production: In the food and beverage industry, temperature sensors are used for sanitary purposes and reducing waste.

Other Applications Include:

Transit & Motorsport Vehicles
Alcohol Breathalyzers
Surface Plates
Heat Exchangers
Drilling
HVAC Applications
Energy Industries

Things To Consider Before Using A Temperature Sensor

Before you decide which temperature sensor is right for your application, you should consider the following:

Temperature Range: The temperature range will determine which temperature sensor you require, as different sensors measure different temperature ranges. The temperature range of the temperature sensor should be on the temperature sensor datasheet.
Accuracy & Stability: The application you are working with is likely to require a certain degree of accuracy and stability. RTDs are the most accurate and stable temperature sensors available, which is why they are used in high-precision applications.
Size: The area available within the application will determine which temperature sensor you select.

Conclusion

Temperature sensors are a device used in our everyday lives to measure the temperature (hotness or coolness) of the air, a liquid, and solid matter, providing a readable measurement via an electrical signal inside the device.

Depending on which application or industry you work in, will depend on which temperature sensor you will require, however, RTD temperature sensors are the most accurate and stable sensor which is why they are used in industrial applications that require high-precision measurements.

If you have any questions regarding temperature sensors or unsure which temperature sensor will best suit your needs, please do not hesitate to contact the world-class team at Atlas Scientific.