Which phenomenon is directly responsible for converting electrical energy into mechanical waves in the ultrasound transducer?

Which phenomenon is directly responsible for converting electrical energy into mechanical waves in the ultrasound transducer?

• A. Piezoelectric effect
• B. Thermoelectric effect
• C. Photoelectric effect
• D. Magnetostrictive effect

Answer: (A)

The mechanism at work is the inverse piezoelectric effect. Piezoelectric crystals, like those used in ultrasound transducers, deform in response to an applied electric field. When an alternating electrical signal drives the crystal, it rapidly expands and contracts, generating ultrasonic waves that propagate into the tissue. The same crystals can then pick up returning mechanical waves and convert them back into electrical signals via the direct piezoelectric effect. Thermoelectric effects rely on temperature differences to create voltage, not to drive mechanical motion. The photoelectric effect involves emission of electrons by light, which doesn’t produce ultrasound waves. Magnetostrictive materials change shape under a magnetic field, and while they can be used in some transducers, the common clinical ultrasound transducer relies on the inverse piezoelectric effect for converting electrical energy into mechanical waves.

The mechanism at work is the inverse piezoelectric effect. Piezoelectric crystals, like those used in ultrasound transducers, deform in response to an applied electric field. When an alternating electrical signal drives the crystal, it rapidly expands and contracts, generating ultrasonic waves that propagate into the tissue. The same crystals can then pick up returning mechanical waves and convert them back into electrical signals via the direct piezoelectric effect.

Thermoelectric effects rely on temperature differences to create voltage, not to drive mechanical motion. The photoelectric effect involves emission of electrons by light, which doesn’t produce ultrasound waves. Magnetostrictive materials change shape under a magnetic field, and while they can be used in some transducers, the common clinical ultrasound transducer relies on the inverse piezoelectric effect for converting electrical energy into mechanical waves.