How to Choose the Right Temperature Sensor?

Technology	How It Works	Typical Temperature Range	Typical Accuracy	Response and Practical Strengths	Limitations and Common Uses
Thermocouple	Two dissimilar metal conductors generate a small voltage that varies with the temperature difference between the measuring and reference junctions.	About −200°C to 1,250°C for commonly used Type K sensors; limits depend on thermocouple type, probe construction, and environment.	Often around ±1–2°C or ±0.75% of the measured temperature for standard-grade sensors; the applicable tolerance depends on type and temperature.	Wide operating range, rugged construction, and fast response with a small exposed junction. Self-powered sensing element.	Requires cold-junction compensation and suitable signal conditioning. Accuracy and long-term stability are generally lower than a good RTD. Common in furnaces, engines, and industrial processes.
RTD (Resistance Temperature Detector)	Measures the predictable change in electrical resistance of a metal element, most commonly platinum.	Approximately −200°C to 600°C for many industrial platinum RTDs; specific designs may have different limits.	Platinum RTD tolerance classes commonly range from about ±0.15°C to ±0.5°C near 0°C; tolerance changes with temperature and sensor class.	Good accuracy, repeatability, and long-term stability. Suitable for precise measurements over a broad moderate-temperature range.	Usually costs more and may respond more slowly than a small thermocouple. Needs excitation and resistance-measurement circuitry. Common in laboratories, process control, and HVAC systems.
Thermistor	Measures the substantial, nonlinear change in resistance of a temperature-sensitive semiconductor material.	Typically about −50°C to 150°C, depending on the thermistor and its packaging.	Often about ±0.1°C to ±1°C over a specified, calibrated range; accuracy depends on calibration and measurement circuitry.	High sensitivity and small size can provide fast response and good accuracy over a limited temperature span.	Nonlinear response and a narrower operating range than many RTDs or thermocouples. Self-heating can affect readings. Common in medical devices, battery packs, and temperature compensation.
Semiconductor temperature sensor	Uses temperature-dependent electrical behavior in an integrated semiconductor circuit to provide an analog voltage, current, or digital reading.	Commonly about −55°C to 150°C, subject to the device rating and operating conditions.	Often around ±0.1°C to ±2°C, depending on the device, calibrated range, and specified conditions.	Easy to interface with electronics; digital versions can simplify wiring and signal conversion. Well suited to compact, low-to-moderate-temperature applications.	Generally unsuitable for very high temperatures or harsh environments. Some devices need close thermal contact and careful placement. Common in circuit boards, consumer electronics, and equipment monitoring.
Infrared (IR) sensor	Estimates an object's surface temperature by detecting emitted infrared radiation without touching the target.	Instrument-dependent; handheld and fixed units commonly cover ranges from below 0°C to several hundred degrees Celsius, with some models extending beyond 1,000°C.	Often specified as approximately ±1–2°C or ±1–2% of the reading, depending on the instrument and measurement conditions.	Non-contact measurement supports moving, inaccessible, or very hot targets. Response is often very fast.	Measures surface temperature, not internal temperature. Results depend on emissivity, field of view, distance, and obstructions such as steam or dust. Common in moving-line inspection and hot or hazardous environments.