6 Types Of Temperature Sensors And Their Characteristics

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The change in its temperature indicates the energy level of a substance. There are various temperature measurement sensors, and they all work by detecting changes in some physical property to determine temperature. We will be covering six fundamental types of temperature sensors or temperature-checking devices in this blog post.


Thermocouples are voltage instruments that use a change in voltage to indicate temperature measurement. A thermocouple’s output voltage increases with temperature, though not always linearly.

Thermocouples are frequently housed in a ceramic or metal shield that shields them from exposure to various conditions. Teflon is a popular outer coating option for metal-sheathed thermocouples, allowing for trouble-free operation in acids and potent caustic solutions.

Resistive Temperature Measuring Devices

Electrical devices are also used to measure resistance in temperature. They make use of another property of matter that changes with temperature—its resistance—instead of a voltage, as the thermocouple does.

RTDs are often more linear than thermocouples. Resistance grows as temperature rises, and they grow in a positive direction. The thermistor, on the other hand, is built altogether differently. It is a very nonlinear semiconductive device with its resistance having an inversely proportional relationship with temperature.

Infrared Sensors

Non-contact sensors include infrared ones such as our infra-View® boiler thermometer, which tracks flue gas temperatures in the furnace ranging from 250°F to 3,000°F. As an illustration, if you hold a common infrared sensor up to the front of your desk without making physical contact, the sensor will radiate information about the desk’s temperature, which is most likely 68°F at standard room temperature.

Ice water will register slightly below zero degrees Celsius in a non-contact measurement due to evaporation, which slightly lowers the expected temperature result. 

Bimetallic Devices

Bimetallic devices benefit from the tendency of metals to expand when heated. Two metals are joined together and mechanically connected to a pointer in these thermometers. The bimetallic strip will expand more than the other side when heated. The temperature reading is also indicated when correctly geared to a pointer.

Bimetallic devices have the benefits of portability and autonomy from a power source. Portability is unquestionably a benefit for the correct application, but they are typically not nearly as accurate as electrical devices. You cannot as quickly record the temperature value as you can with electrical devices like thermocouples or RTDs.


The well-known liquid expansion thermometers are also used to monitor the temperature. They can be divided into two categories, the mercury type and the organic, typically red, liquid kind. The distinction between the two is significant because there are restrictions on how safely mercury devices can be supplied or moved.

Change-of-State Sensors

A change in a material’s condition caused by a change in temperature, such as the transition from ice to water to steam, is what change-of-state temperature sensors measure. Devices of this type might be purchased in the form of labels, lacquers, crayons, or pellets.

It has the advantage of being a tiny, robust, nonelectrical indicator that continuously updates temperature measurement even though it is not completely accurate.

Use our Pyrometer Selector to find the right solution for your temperature monitoring needs and place a request for quote.

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