sensor

A sensor is a device that detects events or changes in its environment and returns a signal that can be measured or recorded. Sensors respond to physical, chemical, or biological stimuli and typically produce an output that is electrical, optical, or digital in nature. They are core components in measurement, control, and monitoring systems, converting a non-electrical quantity into an electrical signal or directly into information that can be processed by a computer or controller.

Sensors are classified by the quantity they measure, such as physical sensors (temperature, pressure, force, motion, light, humidity), chemical sensors (gas, pH, ion concentration), and biosensors (enzymes, antibodies, or living cells used to detect biological analytes). Most sensors rely on a transduction mechanism to convert the sensed quantity into a measurable signal. common transduction methods include changes in electrical resistance, capacitance, inductance, or impedance; piezoelectric or thermoelectric effects; optical absorption, reflection, or emission; and magnetic or radio frequency phenomena.

Key performance attributes include sensitivity, measurement range, resolution, accuracy, repeatability, response time, hysteresis, and stability. Signals from sensors may be analog or digital and often require conditioning, amplification, filtering, and calibration before use in a system or application.

Applications span consumer electronics, automotive technology, industrial automation, medical devices, environmental monitoring, and research. Advances in microfabrication, MEMS technology, and nanomaterials have enabled smaller, cheaper, and more capable sensors with broader integration into everyday devices and infrastructure.