A Low-Impedance Ultrasonic Probe Using a Multilayer Piezoelectric Ceramic

An ultrasonic probe employing a multilayer ceramic is proposed for improving the S/N ratio. The S/N ratio is degraded when the probe impedance rises in relation to parallel combined impedances of cable and receiver circuits. The impedance of n layers of ceramic can be reduced to 1/ n 2 of a single ceramic layer, thus permitting the S/N ratio to be raised. A co-firing multilayer method is introduced to achieve a multilayer ceramic with large adhesive strength. As a result, the S/N ratio has been improved as much as 8 dB over that of conventional probes under the same drive voltage.