Temperature probes, as the name suggests, are devices that are used to measure temperature. This is done through the use of contact-style methods like probes. These probes can measure any changes in temperature-sensitive characteristics like resistance or voltage difference.
They have sensor junctions that come in direct contact with a plastic or metal casing and the probe itself makes contact with the media that is being measured while the sensors within the casing are there to measure resistance or voltage difference. But there are a few different probe types to be aware of depending on their intended use.
Thermocouples
There is far more ground to cover regarding temperature probes than just the different kinds. For instance, there are a ton of accessories like a compression fitting, extension, etc. Probes can be used in a number of technological applications as well.
Thermocouple probes generate temperature-dependent voltage. There are single- and dual-junction designs. On the whole, they are both simple and rugged while covering a wide range of temperatures. The probe can be inserted into a medium or fluid in order to generate a voltage. International codes have been established to help users determine sensitivity and materials for certain applications.
Resistive temperature detectors
Also known as RSDs, these temperature probes are a sort of thermal resistor. That is, they are wire windings that show changes in resistance along with changes in temperature. The hotter they get, the higher the electrical resistance. Depending on the material – like platinum – RTDs can create a very fast, accurate reading over a wider temperature range.
RTD elements typically have spring-like, long wires that are surrounded by a layer of insulation and then enclosed within a metal sheath. Some materials are more expensive than others but the temperature range is among the best, getting up into the 1200 degrees Fahrenheit range. It is also the most interchangeable probe on the market as well while being among the most accurate.
IC temperature or solid state sensors
These are semiconductor sensors that utilize current characteristics of semiconductor diodes versus temperature-sensitive voltage. They are in line with a lot of other options that handle higher voltage or high current outputs, but they are generally not meant to be used in environments where temperatures climb higher than 400 degrees Fahrenheit.
Infrared temperature sensors
These are cool because they absorb the ambient infrared radiation that comes from a heated surface. That incoming light then gets converted into an electrical system, which then corresponds to certain temperatures. T
his is done through a variety of methods, like the expansion of a material like plastic that changes the length of the aforementioned light path. Fiber optic probes are great for situations where a metal probe could be problematic (like an MRI).
Fiber optic sensors
As the name suggests, this probe uses optics to measure certain temperature changes. These probes have a very thin film, like gallium arsenide, that gets deposited right to the end of an optical fiber.
From there, temperatures are deduced from the transmission/reflected absorption spectrum. There are even other types of fiber optic probes that use infrared or luminescence sensors.
Luminescence temperature sensors
Speaking of luminescence sensors, this type of probe has a temperature-sensitive phosphor that gets deposited on the very end of an optical fiber. When temperatures begin to change, it activates the phosphor at the end of the probe. The luminescence can then be measured as a result.
In addition to these different probe types, there are several configurations. Straight, flexible, drop, curved, roller, penetration, air, angled, surface, flat, and clamped all determine who the probe contacts the system that it is trying to measure.