| Thermocouple | Two dissimilar metal conductors generate a small voltage that changes with the temperature difference between the measuring and reference junctions. | About −200 to 1,700 °C, depending on thermocouple type, construction, and environment. | Often around ±1 to ±2.2 °C, or specified as a percentage of the reading; the applicable tolerance depends on type and wire grade. | Typically fractions of a second to several seconds, depending on probe size, sheath, and installation. | Very wide operating range; rugged; suitable for high temperatures; relatively low cost. | Requires cold-junction compensation; output is nonlinear and low-level; accuracy and stability can drift with age or exposure. | Furnaces, kilns, engines, process equipment, and high-temperature testing. |
| RTD (platinum resistance thermometer) | Measures the change in electrical resistance of platinum as temperature changes. Pt100 and Pt1000 are common resistance designs. | Commonly about −200 to 850 °C for platinum elements; the usable range depends on probe construction. | For a Pt100, IEC Class A tolerance is ±(0.15 + 0.002 × |t|) °C, where t is temperature in °C. | Usually about 1 to 10 seconds for a probe; smaller elements can respond faster. | Good accuracy, repeatability, and long-term stability; useful over a broad industrial temperature range. | Generally costs more than a basic thermocouple; needs excitation and suitable wiring; self-heating and lead resistance must be managed. | Industrial process control, laboratories, HVAC systems, and precision equipment. |
| NTC thermistor | Uses a semiconductor material whose resistance decreases as temperature rises. | Commonly about −50 to 150 °C, with the actual range determined by the component and packaging. | Often around ±0.1 to ±1 °C over a specified range for selected parts; performance varies substantially by tolerance and calibration. | Often fractions of a second to several seconds, depending on bead size, encapsulation, and mounting. | High sensitivity over a limited range; compact; inexpensive; simple measurement circuitry. | Strongly nonlinear; narrower useful range; can self-heat; characteristics may vary between parts. | Battery packs, appliances, medical devices, HVAC, and electronic equipment protection. |
| Semiconductor temperature sensor IC | Uses on-chip semiconductor circuitry to provide an analog voltage, digital output, or temperature reading. | Commonly about −55 to 150 °C, depending on the device. | Typically around ±0.5 to ±2 °C over specified conditions; check the individual device’s accuracy limits. | Typically milliseconds to a few seconds, depending on the IC, conversion settings, and thermal coupling. | Easy to interface with electronics; compact; often provides calibrated digital output and built-in signal conditioning. | Limited temperature range; needs a power supply; measurement can be affected by board heating and placement. | Consumer electronics, embedded systems, data loggers, and equipment monitoring. |
| Infrared (non-contact) sensor | Estimates surface temperature by detecting emitted infrared radiation; it does not need to touch the target. | Model-dependent; handheld and fixed instruments commonly cover ranges from below 0 °C to several hundred degrees Celsius, with specialized instruments extending higher. | Often specified as approximately ±1 to ±2 °C or ±1% to ±2% of reading, whichever is greater; depends on instrument and conditions. | Typically milliseconds to about one second for the instrument’s indicated response. | Measures moving, hazardous, inaccessible, or very hot surfaces without contact; fast readings. | Measures surface rather than internal temperature; emissivity, distance-to-spot ratio, reflections, and viewing conditions affect results. | Conveyor inspection, electrical maintenance, food surface checks, and moving-process monitoring. |