Sensors and Transducers

 

A sensor is used to detect a parameter in one form and report it in another form of energy (usually an electrical and/or digital signal). For example, a pressure sensor might detect pressure (a mechanical form of energy) and convert it to electricity for display at a remote gauge.

Transducer is sub domain of sensors, where the output is electrical energy.glass thermometer is a sensor but not a tranducer

A sensor is a device that measures a physical quantity and converts it into a signal which can be read by an observer or by an instrument. For example, a mercury-in-glass thermometer converts the measured temperature into expansion and contraction of a liquid which can be read on a calibrated glass tube. A thermocouple converts temperature to an output voltage which can be read by a voltmeter. For accuracy, most sensors are calibrated against known standards.

A sensor is a device which receives and responds to a signal or stimulus. Here, the term "stimulus" means a property or a quantity that needs to be converted into electrical form. Hence, sensor can be defined as a device which receives a signal and converts it into electrical form which can be further used for electronic devices. A sensor differs from a transducer in the way that a transducer converts one form of energy into other form whereas a sensor converts the received signal into electrical form only.

 

  • Electromagnetic:
    • Antenna - converts electromagnetic waves into electric current and vice versa.
    • Photodetector or Photoresistor (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 only.
  • Electrochemical:
    • pH probes
    • Electro-galvanic fuel cell
    • Hydrogen sensor
  • Electromechanical (electromechanical output devices are generically called actuators):
    • Microelectromechanical systems
    • Vibration powered generator
    • Potentiometer when used for measuring position
    • Load cell converts force to mV/V electrical signal using strain gauge
    • Accelerometer
    • Strain gauge
    • String Potentiometer
    • Air flow sensor
    • Tactile sensor
  • Electroacoustic:
    • Microphone - converts sound into an electrical signal (air pressure → motion of conductor/coil → magnetic field → signal)
    • Pick up (music technology) - converts motion of metal strings into an electrical signal (magnetism → electricity (signal))
    • Tactile transducer - converts solid-state vibrations into electrical signal (vibration → ? → signal)
    • Piezoelectric crystal - converts solid-state electrical moduluations into an electrical signal (vibration → ? → signal)
    • Geophone - convert a ground movement (displacement) into voltage - (vibrations → motion of conductor/coil → magnetic field → signal)
    • Gramophone pick-up - (air pressure → motion → magnetic field → signal)
    • Hydrophone - converts changes in water pressure into an electrical form
    • Sonar transponder (water pressure → motion of conductor/coil → magnetic field → signal)
  • Photoelectric:
    • Photodiode, photoresistor, phototransistor, photomultiplier tube - converts changing light levels into electrical form
  • Electrostatic:
    • Electrometer
  • Thermoelectric:
    • RTD Resistance Temperature Detector
    • Thermocouple
    • Peltier cooler
    • Thermistor (includes PTC resistor and NTC resistor)
  • Radioacoustic:
    • Geiger-Müller tube used for measuring radioactivity.
    • Receiver (radio)

 

 

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An Engineers Community

 

Designed & Maintained By Xtronix

An Engineers Community