transducer

Any device which converts one form of energy into another. A microphone is an acoustic transducer, converting sound waves into electrical signals. Electromechanical transducers convert electrical signals into mechanical oscillations, as in piezo-electric ultrasound generators.

Electrochemical: pH probe electro-galvanic fuel cell Electromechanical: (electromechanical output devices are generically called actuators) electroactive polymers galvanometer MEMS motor, linear motor potentiometer when used for measuring position Accelerometer strain gauge switch Electroacoustic: gramophone pick-up hydrophone - converts changes in water pressure into an electrical form loudspeaker, earphone - converts changes in electrical signals into acoustic form microphone - converts changes in air pressure into an electrical signal piezoelectric crystal - converts pressure changes into electrical form Tactile transducer Photoelectric: Laser diode, light-emitting diode - convert electrical power into forms of light photodiode, phototransistor, photomultiplier tube - converts changing light levels into electrical form Electromagnetic: cathode ray tube (CRT) - converts electrical signals into visual form fluorescent lamp, light bulb - converts electrical power into visible light magnetic cartridge - converts motion into electrical form photocell or light-dependent resistor (LDR) - converts changes in light levels into resistance changes tape head - converts changing magnetic fields into electrical form Hall effect sensor - converts a magnetic field level into electrical form Electrostatic: electrometer liquid crystal display (LCD) Thermoelectric: RTD Resistance Temperature Detector thermocouple Peltier cooler thermistor (includes PTC resistor and NTC resistor) Other: Geiger-Müller tube used for measuring radioactivity.