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The Ultrasound Transducer and Its Parts

The ultrasound transducer, also known as probe or tranceiver (because it transmits and receives signals) is called the heart of the ultrasound machine, the most important part of the ultrasound machine and the most expensive as well.

Ultrasound transducer

Below are the major parts and functions of the transducer:

  • Coaxial cable (connector) – known as connector; provides electrical impulse
  • Plastic housing – provide structural support for internal parts
  • Acoustic insulator – prevents sound from passing into the housing
  • Backing material – shortens the sonic pulse and is designed to cushion the movement of the crystals once the electrical stimulus is remove. It is made of tungsten, rubber, and resin
  • Live electrode – absorbs sound waves transmitted back to the transducer
  • Crystal element – where sound waves are produce and the active part of the transducer. This possesses piezoelectric effect and ferroelectrics

Piezoelectric – is the fundamental physical principle of all medical u/s. It is the generation of an electric voltage when a crystal is compressed

Ferroelectrics – artificial piezoelectric material

PZT – Lead Zirconate Titanate

PZT – manufactured by heating a ceramic in a strong electrical field causing alignment of dipole

  • Ground electrode – protects the patient from electric shock
  • Face/insulated cover – contains inside quarter wave matching layer (QWML)
  • Protective acoustic window – designed to match the crystal and transmit the u/s beam and can be found in front of transducer and contact with patient

Quarter wave matching layer (QWML) – most expensive and water-resistant. It is the layer of material located in front of the transducer used to transmit ultrasound more efficiently to the patient


The author is a Radiologic Technologist, currently in the academic field, hoping to mold and produce future Radiologic Technologists who will be theoretically and technologically competent.

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