A meal is only ready and safe to ingest if properly cooked. Otherwise, you risk getting food poisoning or any other food-related illness. A probe thermometer is thus a necessary meal prepping tool, domestically and commercially. It ensures food is cooked under an accurate internal temperature required to eliminate any present harmful bacteria.
Interestingly, probe thermometers are not solely used for checking food internal temperatures. As industry leaders Process Parameters explains, these temperature sensors also control and regulate temperatures in buildings, water distribution panels, and refrigerators. The thermometers are thus specially designed for their intended purpose. This article offers a detailed analysis of the different types of commonly used thermometer probes.
Different Types of Temperature Probes
Temperature probes can generally be defined as different types of sensors used for measuring temperature. Thanks to technological advancement, about four sensors are used in present-day electronics: thermocouples, RTDs, thermistors, and semiconductor-based integrated circuits.
Thermocouples
Thermocouples are the most popular of all temperature probes. These thermometers are widely preferred for their self-sufficiency. For instance, they have an in-built power system, do not require any excitation, can be used in wide temperature ranges, and their response time is prompt. Examples of thermocouples applications include thermostats, thermometers, health facilities, sensors, and vehicle diagnostics.
A thermocouple comprises two wires of different metal types. When the two metals join, an electrical junction known as a measuring junction is created. Temperature variations at the junction thus create a voltage which is later translated into a temperature reading – a mechanism referred to as the Seebeck effect.
Types of thermocouples
Multiple thermocouples are designed uniquely for their target application hence the difference in their temperature range and lustiness. The varying types are named and classified by letters to indicate their level of sensitivity. Examples of these types include:
Type F – conductor alloy is Nickel-Chromium/Constantan
Type J – conductor alloy is Iron/Constantan
Type K – conductor alloy is Nickel-Chromium/Nickel Aluminium
Type N – conductor alloy is Nicrosil/Nisil
Type T – conductor alloy is Copper/Constantan
Resistance Temperature Detector
Every time the temperature of an object changes, a consequent resistance is also felt on the metal. The functioning mechanism of RTDs is based on this reaction. It is a resistor built with high-defined resistance versus temperature factors.
The most suitable material used to make most RTDs is platinum. Platinum is highly preferred for its nature to make a linear response to any temperature variation. This means that they have stable characteristics in their response to changes in temperature in terms of accuracy, repeatable response, and temperature sensing range.
Platinum Resistance Temperature Detectors (PRTD) are mostly designed with a 100 Ω to 1000 Ω resistance from 0°C. The detectors are consequently named PT100 and PT1000 regarding their resistance level. RTDs are thus used in applications that demand high precision, given their guaranteed repeatability.
Thermistors
A thermistor is an electric resistor with a highly sensitive sensor to thermal energy that is used for measuring temperature in the most accurate and cost-efficient way. Like RTDs, thermistors function on the same principle that temperature variations result in measurable resistance changes.
Polymers and ceramics are the common materials used to make thermistors. In terms of cost, thermistors are cheaper than RTDs, but thermistors are less accurate in terms of precision.
Additionally, thermistors are non-linear in matters of temperature resistance. This nature is caused by their Negative Temperature Coefficient (NTC) resistance which reduces as the temperature increases. Given this temperature measurement application, the output data is thus digitally corrected before interpretation.
Semiconductor-Based Integrated Circuits
Semiconductor-based ICs are temperature probes with transistor elements in or on a semiconductor material used to measure both internal and external temperature. These appliances have a two-fold sensor design: local and remote digital temperature.
A local temperature sensor measures its die temperature with the physical properties of a transistor using either a digital or analog output. These temperature sensors detect the temperature change on the circuit boards or the air surrounding them.
So, What are the 4 Types of Thermometer Probes?
On the other hand, a remote digital sensor detects and measures an external transistor’s thermal temperature. Unlike the local temperature sensors, the transistors in remote digital sensors are located opposite the sensor chip.
Thermocouples, RTDs, thermistors, and semiconductor-based ICs are today’s main types of probe thermometers. Thermocouples are widely preferred for their cheap, durable, and robust properties. RTDs may have a lower effective rate than thermocouples. Still, they are used in multiple applications for their accuracy and repeatability in temperature measurements.
Thermistors have lower effectiveness than RTDs and require data revision to ensure accurate output. Semiconductor-based ICs have a wide receiver for their flexibility and portable state, but their temperature range is quite limited. There is a vast list of available temperature probes, but the above four have a proven and diverse effectiveness.
Nicholas Porter is an active technology enthusiast and a leading voice in personal computing. As a key contributor to Digital Edge PC, Nicholas simplifies complex topics, making them accessible for all skill levels.
