Thermistors, or thermally sensitive resistors, are ceramic semiconductors that are capable of exhibiting a resistance change in response to shifts in temperature. Commonly used as temperature sensors for applications ranging from refrigerators to aerospace applications, thermistors are an important component for countless systems. To help you better understand the functionality of thermistors, their types, and their benefits, we will discuss them more in detail in this blog.
Depending on the materials that are used to construct a thermistor, such temperature sensors may fall into one of two categories. NTC thermistors are those that exhibit resistance drops as temperatures rise. This is due to the thermal agitation of the valency band, causing an increase of conduction electrons. NTC components are often used as a temperature sensor, or they may be placed in series with a circuit to operate as an inrush current limiter.
The other major type of thermistor is the PTC variation, those of which feature resistance increases as temperatures rise. The rise of resistance is a result of increased thermal lattice agitations, especially those that have impurities or imperfections. Generally, PTC thermistors are placed in a series with a circuit, allowing them to protect various systems from overcurrent conditions as a type of resettable fuse.
For the construction of thermistors, such components are made up of metallic oxides that are pressed into a disk, bead, or cylindrical shape before being encapsulated within epoxy or glass. Fairly inexpensive and easy to use, thermistors are beneficial due to their sturdiness and their predictability in terms of temperature fluctuations. Despite their inability to perform well under temperature extremes, they are one of the most optimal choices when very precise temperature readings are necessary.
With their resistance shifts as a result of exposure to temperature changes, thermistors can “read” temperatures through the analysis of such changes. Resistance changes are not linear like other temperature sensors, and a graphed line of changes will often differ based on the construction of the thermistor and its materials. As such, one should refer to manufacturer specifications or established graphs to determine how resistance changes across varying temperature levels.
To find the best thermistor for a given application, one should consider the type of material that is being measured, such as whether the material is a solid, liquid, or gas. As an example, a solid device that requires embedding may benefit from a bead thermistor, while an optical surface may require a rod, disk, or cylindrical head. Typically, the shape of the thermistor should permit maximum surface contact with the measured device or material. Additionally, the connection to the monitored object must be formed with the use of high thermally conductive paste or epoxy glue that is non-conductive.
With their various types and capabilities, thermistors may be used for temperature sensors, digital thermometers, food processing and handling, electronics, medical devices, communication, and so much more. By considering your particular needs and requirements, you can best narrow down the exact device that will benefit your application. Once you are ready to make a purchase, let the experts at Purchasing Management 360 help you secure all you need with unmatched pricing and lead times.
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