Which component is the active element in the transducer?

Which component is the active element in the transducer?

• A. matching layer
• B. active crystal
• C. wire
• D. casing

Answer: (B)

The active element is the piezoelectric crystal, because it is the part that directly converts energy between electrical and mechanical forms. When the transducer is pulsed, the crystal deforms rapidly due to the inverse piezoelectric effect, generating the ultrasound wave. On receive, the arriving echoes cause the crystal to vibrate and produce electrical signals that the system processes. The matching layer sits on top to improve energy transfer by matching acoustic impedances, which helps the beam reach tissue more efficiently. The wire simply carries signals to and from the crystal, and the casing protects the assembly and shapes the beam. Since only the crystal actively converts energy in both transmission and reception, it is the active element.

The active element is the piezoelectric crystal, because it is the part that directly converts energy between electrical and mechanical forms. When the transducer is pulsed, the crystal deforms rapidly due to the inverse piezoelectric effect, generating the ultrasound wave. On receive, the arriving echoes cause the crystal to vibrate and produce electrical signals that the system processes. The matching layer sits on top to improve energy transfer by matching acoustic impedances, which helps the beam reach tissue more efficiently. The wire simply carries signals to and from the crystal, and the casing protects the assembly and shapes the beam. Since only the crystal actively converts energy in both transmission and reception, it is the active element.