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.
Development of Miniature Needle-Type Hydrophone with Lead Zirconate Titanate Polycrystalline Film Deposited by Hydrothermal Method
A needle-type miniature hydrophone was developed using hydrothermally deposited lead zirconate titanate (PZT) polycrystalline films on a titanium (Ti) wire with a diameter of 0.3 mm in this study. Two types of hydrophones were fabricated as a trial for this paper. One is a hydrophone with hydrothermally deposited PZT polycrystalline films on the end surface and side surface near the end of the Ti wire. The other one is a hydrophone with hydrothermally deposited PZT polycrystalline films only on the end surface of the Ti wire. We measured the frequency characteristics of the relative receiving sensitivity and directivity of the fabricated hydrophones. The frequency characteristics of the relative receiving sensitivities of the fabricated hydrophone type A or B were measured in the frequency range from 1 to 20 MHz. Our hydrophone with deposited PZT films on the end and side faces of the Ti wire had problems in the directivity of relative receiving sensitivity. The relative sensitivity of the side direction was higher than that of the front direction. The directivity of our hydrophone with hydrothermally deposited PZT films only on the end surface of the Ti wire was improved remarkably.
Teaching self-care to delinquent adolescents.
Adolescent delinquency is an ever-increasing societal concern. Certain health problems are concentrated in the delinquent population. Families of delinquent youths often fail to reinforce self-care. Therefore health care providers need to focus on ways to teach delinquent adolescents to care for themselves. This article reviews delinquency and characteristics of juvenile delinquents and their families. A model is presented to guide health care providers to assess delinquent adolescents' abilities to care for themselves and to teach them strategies for self-care.