Non-destructive detection of material fatigue in artificial heart by ultrasonic spectroscopy.

超声光谱无损检测人工心脏材料疲劳

• 批准号: 07458234
• 负责人: NITTA Shin-ichi
• 金额: $ 4.1万
• 依托单位: Tohoku University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (B)
• 财政年份: 1995
• 资助国家: 日本
• 起止时间: 1995 至 1996
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07458234/
• 关键词: Artificial heart,; Material Fatigue,; Ultrasound,; Frequency domain analysis,; Acoustic microscopy,; Ultrasonic spectroscopy; 超音波スペクトロコピー

Left ventricular assist device (LVAD) has been clinically applied for the treatment of severe heart failure in recent years. As the period of using LVAD is expanded to nearly one year, the detection of material damage has been necessitated. In order to detect the material fatigue, low frequency ultrasonic properties of the material were assessed by the frequency domain analysis of the pulsed ultrasound, and the surface morphology of the material was visualized by the acoustic microscopy.A3.5 MHz linear transducer was placed above the sample in a water tank. The system was modified to access to the rf signals at the output of the time gain controlled (TCG) amplifier, before any significant nonlinear processing, such as compression or rectification, was performed. To observe the frequency dependent characteristics of the received pulse, the Fast Fourier Transform (FFT) of the data was computed. The significant differences of FFT waveforms were observed between new and fatigued materials. Ultrasonic method could detect the material fatigue, although the appearance and the thickness of the samples did not show significant change.A specially developed scanning acoustic microscope system, operating in the frequency range of 100-200MHz, was employed. In the amplitude image of new material, there were no significant cracks or abnormal structure on the surface. Although the surface seemed to be smooth in the amplitude image, the surface was found to be distorted in the phase image. Very small crack and abnormal powder structure was detected in the amplitude image. In the phase image, the distortion was more prominent than that of new material.Both in low and high frequencies, ultrasonic approaches to evaluate the material revealed the material damage. Although this study was performed in the static condition, ultrasonic method should be used in the beating condition in the next stage investigation.

左心室辅助装置（LVAD）是近年来临床上应用于治疗严重心力衰竭的一种新型装置。随着LVAD的使用时间延长到近一年，有必要检测材料损坏。为了检测材料的疲劳性能，采用低频脉冲超声频域分析法对材料的超声特性进行了评价，并采用声显微镜观察了材料的表面形貌。该系统被修改为在执行任何重要的非线性处理（例如压缩或整流）之前访问时间增益控制（TCG）放大器的输出处的RF信号。为了观察接收脉冲的频率依赖特性，计算数据的快速傅立叶变换（FFT）。新材料和疲劳材料的FFT波形存在显著差异。超声方法可以检测材料的疲劳，虽然样品的外观和厚度没有显着变化，一个专门开发的扫描声显微镜系统，工作频率范围为100- 200 MHz。在新材料的振幅图像中，表面没有明显的裂纹或异常结构。虽然表面在振幅图像中似乎是平滑的，但在相位图像中发现表面是扭曲的。在振幅图像中检测到非常小的裂纹和异常粉末结构。在相位图中，变形比新材料的变形更明显，无论在低频还是高频，超声方法都能揭示材料的损伤。虽然本研究是在静态条件下进行的，但在下一阶段的研究中，应使用超声方法在打浆条件下进行。

项目成果

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