ABSTRACT
The transducer is the device that actually converts electrical transmission pulses into ultrasonic pulses and, conversely, ultrasonic echo pulses into electrical echo signals. The simplest way to interrogate all the scan lines that make up a B-mode image is to physically move the transducer so that the beam is swept through the tissues as the pulse-echo cycle is repeated. All transducers or transducer elements have the same basic components: a piezoelectric plate, a matching layer and a backing layer. The actual ultrasound-generating and detecting component is a thin piezoelectric plate. Piezoelectric materials expand or contract when a positive or negative electrical voltage is applied across them and, conversely, generate positive or negative voltages when compressed or stretched by an external force. Lead zirconate titanate has advantages as a transducer material in that it is efficient at converting electrical energy to mechanical energy, and vice versa, and is relatively easy to machine or mould to any required shape or size.
