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.
Semiautomated quantification of the fibrous tissue response to complex three-dimensional filamentous scaffolds using digital image analysis.
Fibrosis represents a relevant response to the implantation of biomaterials, which occurs not only at the tissue-material interface (fibrotic encapsulation) but also within the void fraction of complex three-dimensional (3D) biomaterial constructions (fibrotic ingrowth). Usual evaluation of the biocompatibility mostly depicts fibrosis at the interface of the biomaterial using semiquantitative scores. Here, the relations between encapsulation and infiltrating fibrotic growth are poorly represented. Virtual pathology and digital image analysis provide new strategies to assess fibrosis in a more differentiated way. In this study, we adopted a method previously used to quantify fibrosis in visceral organs to the quantification of fibrosis to 3D biomaterials. In a proof-of-concept study, we transferred the "Collagen Proportionate Area" (CPA) analysis from hepatology to the field of biomaterials. As one task of an experimental animal study, we used CPA analysis to quantify the fibrotic ingrowth into a filamentous scaffold after subcutaneous implantation. We were able to demonstrate that the application of the CPA analysis is well suited as an additional fibrosis evaluation strategy for new biomaterial constructions. The CPA method can contribute to a better understanding of the fibrotic interactions between 3D scaffolds and the host tissue responses.