Akito Endo

Fundamental Study on One-Dimensional-Array Medical Ultrasound Probe with Piezoelectric Polycrystalline Film by Hydrothermal Method: Experimental Fabrication of One-Dimensional-Array Ultrasound Probe

We deposited a lead zirconate titanete (PZT) polycrystalline film on a titanium substrate by the hydrothermal method and fabricated a transducer using the PZT film for use as an ultrasound probe. A 10 MHz miniature one-dimensional-array medical ultrasound probe containing the PZT film was developed. After sputtering titanium on the surface of a hydroxyapatite substrate, the titanium film on the substrate was etched by the photolithography to form a one-dimensional titanium film electrode array. We could thus fabricate a miniature one-dimensional-array ultrasound probe by the hydrothermal method. Transmitted ultrasound pulses from a 10 MHz commercial ultrasound probe were received by the newly fabricated one-dimensional-array ultrasound probe. The fabrication process of the probe and the results of experiments on receiving waveforms were reported in this paper.

Modification of deposition process of piezoelectric polycrystalline film by hydrothermal method -Improvement of the deposition process by pre-treatment using hydrogen peroxide

We have studied on hydro-thermally synthesis of Pb(Ti,Zr)O3 (PZT)piezoelectric polycrystalline thick film on titanium (Ti) substrate. The purpose of this study is resolving the problems for application of PZT hydrothermal polycrystalline thick film to the ultra miniature high frequency medical ultrasound array probe. The problems were the existence of pinholes in the deposited PZT film, the rough surface of that, low dielectric breakdown electric field etc. The surface of Ti substrate was pretreated to have hydrophilic property by using high reactivity of hydrogen peroxide for resolving the problems in this study. As results, hydrophilic property on the surface of Ti substrate was improved. Surface of PZT hydrothermal polycrystalline thick film without pinholes and smooth surface of that were obtained. Furthermore, the material properties like density, Young’s modulus and piezoelectric constant d31 were increased by the pretreatment of Ti substrate. Consequently, dielectric breakdown electric field of PZT hydrothermal polycrystalline film was improved.

Study on dispersion and surface modification of diamond powders by ultrasound exposure

When diamond particles are used as abrasive agents, diamond particles have to disperse homogeneously. Consequently, many dispersants are developed to improve the dispersion property of abrasive agents, whereas improvement of surface properties of abrasive agents using dispersant is not essential. We attempted intrinsic surface modification of diamond particles used as abrasive agents by ultrasound exposure. The change of zeta potential by ultrasound exposure was confirmed. Sub-micro diamond particles with average size smaller than 0.3 /spl mu/m were obtained.

P5K-5 Performance Estimation of Ultra-Miniature One Dimensional Array Ultrasound Probe with Hydrothermally Synthesized PZT Polycrystalline Film Transducers

One-dimensional array ultrasound probe was fabricated with 8 hydrothermally synthesized lead zirconate titanate (PZT) poly-crystalline film transducer elements with element width of about 40 mum, element length of 4 mm and element pitch of 75 mum by deposition of PZT poly-crystalline films on the titanium (Ti) electrode array on the hydroxyapatite (HAp) substrate. Although this ultrasound probe has no acoustic matching layer, it was found that it could receive ultrasound pulse with wide frequency band and short duration time. Furthermore, this 1 D array probe showed element factor of +/- 68 degree in scanning direction and element factor of about +/- 3 degree in slice direction and group factor of about +/- 6 degree in scanning direction, This probe has very wide element factor in scanning direction. However, it could be confirmed that the sensitive area in the receiving sensitivity can be concentrated within the narrow angel range of +/- 6 degree in desired front direction when ultrasound pulse wave was received with all 8 transducer elements in the test fabricated 1D array probe.

P1M-2 Development of Miniature Ultrasonic Probe with PZT Film Deposited by Hydrothermal Method

Recently, the PZT poly-crystalline film deposited on titanium substrate by hydrothermal method has been studied actively for development of a small actuator and ultrasonic sensor in our laboratory. The PZT poly-crystalline films were deposited on a titanium substrate in KOH solution used as mineralizer which included Pb ion, Ti ion, and Zr ion under high temperature (about 150degC) and high pressure (about 4 kPa). We reported on the needle type miniature hydrophone and the ultrasonic transducer with hydrothermally synthesized PZT poly-crystalline films in 2005 IEEE International Ultrasonics Symposium in Rotterdam. It has confirmed that the hydrothermally synthesized PZT poly-crystalline films showed wide band frequency characteristics in MHz band of the sensitivities. It is thought that miniature ultrasonic probe with wide frequency band characteristics of sensitivities can be fabricated by using the hydrothermally synthesized PZT poly-crystalline films. The miniature ultrasonic probes were fabricated by hydrothermally deposited PZT poly-crystalline film on an end of the titanium wire with diameter of 0.6 mm and length of 50mm. The performances of trially fabricated ultrasound probes were measured. Ultrasonic imaging experiments using a target in water were performed with the trially fabricated ultrasonic probe with hydrothermally synthesized PZT films. As a result, it was confirmed that this probe has a center frequency of 16 MHz, a bandwidth of 80%, and distance resolution more than 80 micrometers. We will report about the structure and performance of the fabricated ultrasound probe with hydrothermally synthesized PZT poly-crystalline film and the results of imaging experiments under water

P3P-5 Fundamental Study on Array Type Medical Ultrasound Probe with Hydrothermally Synthesized PZT Poly-Crystalline Film

In this study, in order to apply the hydrothermally synthesized piezoelectric polycrystalline films to the medical miniature 1-dimensional array type ultrasound probes with resonance frequency of 10 MHz, the hydroxyapatite was employed as the material for the substrate. After sputtering of pure titanium on the surface of hydroxyapatite substrate, the titanium film was etched using photo-etching method to form 1-dimensional titanium film electrodes array with element pitch of 75 mum, element width of 40 mum and element length of 4mm in order to scan ultrasound beam electronically by sector scan mode using phased array technique. We tried to deposit PZT poly-crystalline film hydrothermally on the titanium film electrodes. The deposited PZT poly-crystalline film has thickness of about 10 mum on the 1-dimensional array titanium electrode pattern. We could succeed trial fabrication of the miniature 1-dimensional array type ultrasound probe. The sputtered and etched titanium film electrodes were used as the electrodes for signal lines of the 1-dimensional array type ultrasound probe. Furthermore, a gold electrode was deposited as a common ground electrode all over the surface of 1-dimensional hydrothermally synthesized PZT poly-crystalline film vibrators. Transmitted ultrasound pulse from 10 MHz commercial ultrasound probe was received by the trially fabricated 1-dimensional array type ultrasound probe with hydrothermally synthesized PZT poly-crystalline film vibrators

Basic study on one‐dimensional transducer array using hydrothermally synthesized lead zirconium titanete poly‐crystalline film

Recently, high‐frequency miniature medical ultrasound probes with high resolution were actively developed. However, it is difficult to fabricate such tiny ultrasound probes using piezoelectric ceramic vibrator with thickness less than 100 μm. We deposited a PZT poly‐crystalline film on a titanium substrate using the hydrothermal method and developed transducers using the PZT poly‐crystalline film for ultrasound probes. In this study, we applied it to a miniature medical one‐dimensional (1‐D)‐array‐type ultrasound probe with resonance frequency of 10 MHz. After sputtering of pure titanium on the surface of a hydroxyapatite substrate, the titanium film was etched using the photolithography method to form a 1‐D titanium film electrode array with 75 μm element pitch, 40 μm element width, and 4 mm element length to scan an ultrasound beam electronically by sector scan mode using phased‐array technique. Thereby we fabricated a miniature 1‐D‐array‐type ultrasound probe. A transmitted ultrasound pulse from 10 MHz...

Development of miniature ultrasonic probe with piezoelectric poly‐crystalline film deposited by hydrothermal method

Recently, a PZT poly‐crystalline film deposited on titanium substrate using the hydrothermal method was studied actively in our laboratory for development of an ultrasonic sensor. These PZT poly‐crystalline films can form PZT poly‐crystalline films easily on substrates of complex shape using hydrothermal method. We reported a needle‐type miniature hydrophone and the ultrasonic transducer with hydrothermally synthesized PZT poly‐crystalline films. Results confirmed that the hydrothermally synthesized PZT poly‐crystalline films showed wideband frequency characteristics in the megahertz band of sensitivities. A miniature ultrasonic probe with wide frequency band characteristics of sensitivities is thought to be producible using hydrothermally synthesized PZT poly‐crystalline films. Miniature ultrasonic probes were fabricated using hydrothermally deposited PZT poly‐crystalline film on the end of 0.6‐mm‐diam titanium wires. Ultrasonic imaging experiments of a target in water were performed using a fabricated u...