TemperatureSensor

Temperature sensors measure temperature or temperature change and convert it into an electrical signal for monitoring, control, or data collection. They vary in principle, range, speed, and accuracy and are used across industries and in consumer electronics. Common types include contact sensors such as thermocouples, resistance temperature detectors (RTDs), and thermistors; non-contact infrared sensors; and semiconductor sensors integrated into integrated circuits or microprocessors.

Thermocouples consist of two dissimilar metals joined at one end; the voltage generated at the junction is proportional to temperature. They operate over wide ranges and are robust and inexpensive but require cold-junction compensation and linearization for precise measurements. RTDs use a metal resistor, commonly platinum (Pt100 or Pt1000), whose resistance increases with temperature. They offer high accuracy and stability but have higher cost and slower response than some alternatives. Thermistors are temperature-sensitive ceramics with negative (NTC) or positive (PTC) temperature coefficients; NTC thermistors provide high sensitivity over a limited range, while PTC types are used for specialized sensing and protection roles.

Non-contact infrared sensors measure emitted infrared radiation to infer surface temperature; they are fast and do not touch the object but require emissivity calibration and can be affected by surface properties and atmosphere. Semiconductor temperature sensors are integrated devices (diodes or transistors) that produce a voltage or current proportional to absolute temperature and are common for digital monitoring in electronics. Digital temperature sensors output calibrated digital data via interfaces such as I2C, SPI, or 1-wire, often with on-chip conversion and compensation.

Applications include HVAC, industrial process control, automotive, consumer electronics, medical devices, and environmental monitoring. Key specifications are measurement range, accuracy, resolution, response time, stability, and self-heating, with calibration typically traceable to standards bodies.