Development of Biological Ultrasonic Micro-Specroscopy System

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A biological ultrasonic micro-spectroscopy (Bio-UMS) system has been developed as a new research tool to characterize biological soft and hard tissues on a microscopic scale in the VHF and UHF ranges.A method has been developed for measuring the bulk acoustic properties such as velocity, attenuation, and density in reflection and transmission modes with the biological soft tissue specimen sandwiched between the parallel surfaces of fused quartz buffer rods having ZnO piezoelectric film transducers on their opposite ends. The method is an acoustic transmission line comparison method wherein the reference medium is distilled water. Techniques of precise mechanical alignment for parallelism of the two rod surfaces, movement to adjust the gap distance, and signal processing are involved in order to obtain high measurement accuracy. Results of measurements with bovine tissues of liver, heart muscle, and fat have been presented.A reflection-type acoustic microscope system for biological soft … More tissue characterization has been developed. This system operates in both amplitude and phase modes, and can measure acoustic properties, viz., velocity and attenuation, of tissues in two-dimensional color imaging, as well as at arbitrary points in an imaging area. A demonstration for dog cardiac infarcted tissues prepared from a formalin-fixed, paraffin-embedded sample has been made. Spatial hanges of acoustic properties in tissues due to pathological degeneration were quantitatively determined. A revised model for the quantitative characterization has been also proposed wherein the effects of acoustic multiple reflection and viscosity of the sample have been taken into account.Acoustic microscopy has been discussed to investigate viscoelastic properties of biological hard tissues, taking dental materials. The quantitative applications of an line-focus-beam (LFB) acoustic microscope, as well as the imaging applications of a point-focus-beam (PFB) acoustic microscope, have satisfactorily demonstrated the possibilities. In particular, the LFB acoustic microscope can be expected to play an important role as a powerful tool to solve basic and practical problems in all kinds of dental materials, including dental hard tissues of enamel and dentine, and dental porcelains and composites for repairing human teeth. Less