P1J-4 Evaluation of Small Ultrasonic Probe Using Lead Zirconate Titanate Film Deposited by Hydrothermal Method
Recently, our laboratory has explored the possibility of using lead zirconate titanate [PZT] polycrystalline film deposited hydrothermally on titanium substrate to fabricate a small actuator and ultrasound sensor. Hydrothermally deposited PZT polycrystalline films have piezoelectricity without a poling process, and it is easy to deposit PZT polycrystalline films on substrates that are tiny or complexly shaped. We confirmed that hydrothermally synthesized PZT polycrystalline films have wideband frequency characteristics with sensitivities in the megahertz band. It is thought that miniature ultrasound probes with wide- frequency band characteristics can be fabricated using hydrothermally synthesized PZT polycrystalline films. In our last report we assessed methods to produce a miniature ultrasound probe and transceiver characteristics. Here, the reception and transmission directivities of such a probe were measured at 5, 10, 15, and 20 MHz. The results showed that, except at 5 MHz, the theoretical and experimental values agreed. The difference at 5 MHz is attributed to the effect of the resonance frequency of the diameter direction.
Lead Zirconate Titanate Thick-Film Ultrasonic Transducer for 1 to 20 MHz Frequency Bands Fabricated by Hydrothermal Polycrystal Growth
A thickness vibration mode ultrasonic transducer was fabricated by hydrothermal deposition of lead zirconate titanate polycrystalline thick film. This hydrothermal polycrystalline PZT thick-film (HPTF-PZT) ultrasonic transducer was studied for its wide-frequency-band transmission characteristics. The transducer had a 50-µm-thick PZT layer on a 50-µm-thick titanium substrate in an active area of 8 mm×8 mm. The experimental results showed the HPTF-PZT ultrasonic transducer radiated a single ultrasound pulse in the frequency range from 1 to 20 MHz with a 20 dB deviation. Additionally, this transducer generated a 2 MHz sawtooth ultrasonic wave with odd-and even order-harmonic components from the 2nd to the 11th harmonics. These results indicate that the fabricated ultrasonic transducer has satisfactory wide-band characteristics for a MHz frequency range ultrasonic transmitter.
Broadband Transducers Using Effectively Graded Piezoelectric Plates for Generation of Short-Pulse Ultrasound
Broadband ultrasound transducers that utilize piezoelectric materials having an effectively graded piezoelectric parameter and/or an excitation electric field applied across the piezoelectric material are investigated. These transducers are constructed by forming a number of fine V-grooves on one surface of a piezoelectric plate. The broadband frequency characteristic of the proposed transducer is demonstrated by experiments of wave generation in water. Analysis by the finite-element method proves that even-order resonance modes are also excited in the plate with a grooved configuration.