sensors

A sensor is a device that detects a physical, chemical, or biological stimulus and converts it into a signal that can be measured or recorded. The output is typically an electrical signal, but may be optical, thermal, or pneumatic. Sensors are core components of measurement and control systems, providing data that enable monitoring, diagnostics, and automation.

Common sensor types are classified by the quantity they measure and by the transduction principle. Temperature sensors may use thermocouples or resistance temperature detectors; pressure sensors can be capacitive, piezoresistive, or piezoelectric; light sensors include photodiodes and image sensors; magnetic sensors use Hall effect. Chemical and biosensors convert chemical interactions into electrical signals via electrochemical, optical, or enzymatic transduction.

Key performance characteristics include sensitivity, which describes the signal change per unit input; range, the span of measurable values; accuracy and precision, linearity, resolution, and repeatability. Response time, hysteresis, and drift affect dynamic behavior. Calibration, environment, and aging influence accuracy, requiring periodic verification and compensation in software or circuitry.

Applications span industrial automation, automotive systems, consumer electronics, environmental monitoring, healthcare, and security. Sensor networks and Internet of Things deployments collect large data sets for monitoring, control, and analytics. Integrated sensor arrays and multimodal sensing enable more robust perception in robotics and smart systems.

Ongoing challenges include ensuring reliability in harsh environments, reducing size and power consumption, and maintaining calibration over time. Advances in microfabrication, materials science, and data fusion are expanding sensor capability and enabling new applications.