Transductors

A transductor, commonly called a transducer, is a device that converts energy or information from one physical form to another. Transducers can be passive, drawing energy from the quantity being measured, or active, requiring an external power source. They are typically categorized as sensors, which convert a physical quantity into an electrical signal, or actuators, which convert an electrical signal into a physical action. Some devices perform bidirectional transduction and are used in feedback systems within audio, instrumentation, and control equipment.

Transduction mechanisms arise from various physical effects, including piezoelectric, electromagnetic induction, photovoltaic, photoconductive, thermoelectric, and electrochemical phenomena. Devices are often described by their input–output pair:

- Mechanical to electrical: microphones, piezoelectric sensors

- Electrical to mechanical: loudspeakers, piezoelectric actuators

- Optical to electrical: photodiodes, solar cells

- Electrical to optical: light-emitting diodes, electro-optic modulators

- Thermal to electrical: thermocouples and related temperature sensors

- Electrical to thermal: electrical heaters or actuators that produce heat

Performance characteristics used to evaluate transducers include sensitivity (or gain), linearity, bandwidth, noise, response time, and temperature stability. Calibration and aging can affect accuracy over time. Transducers are integral to measurement, control, and information processing systems, enabling devices to perceive physical conditions, communicate information, or produce controlled physical effects.

Applications span scientific instrumentation, consumer electronics, medical devices, industrial automation, energy harvesting, and sensing in automotive and aerospace technologies. The effectiveness of a transducer depends on how well its input–output relationship matches the needs of the system, its robustness to environmental factors, and its compatibility with the surrounding circuitry and signal processing. See also: sensor, actuator, transducer as a concept in measurement systems.