| Biomechanical properties of tissues vary according to the pathological changes.Due to the lack of quantitative biomechanical tools for assessment, palpation is stillwidely used to evaluate firmness of soft tissues in common clinical practice. Theultimate objective of this thesis is to development of an ultrasonic diagnosticinstrument for biomechanics characteristic of soft tissues, withdraw the flexibleinformation from ultrasonic echo signals, and get flexible characteristic parameter ofsoft tissues.This thesis completes this type of ultrasonic diagnostic instrument's design anddevelopment. A sensor combining ultrasonic probe and load cell functions as ahand-held probe to collect the signals of ultrasonic echo and force, after the DSPprocessing, getting the strain and stress, then gets the flexible characteristic parameterof the soft tissue.In analog circuit design, this text mainly completes the trigger of ultrasonicprobe, ultrasonic echo's magnify & filter and the pressure signal's sample andmagnify. The DSP is used as the CPU in the development of this system. The wholesystem is control by DSP. This system includes three units of signals' sample,processing, and display. Using C programming and assembly languages developmentthe system's software, completed the development and the design of the instrument.The quasi-linear viscoelastic (QLV) parameters were extracted via a curve-fittingprocedure by predicting the force transient response from the deformation data. It wasdemonstrated that the biomechanical property response of soft tissues is nonlinear andthe viscoelastic properties are time-correlated. It can be concluded that the materialconstant is a reflection of the viscoelastic property of soft tissues, which can beapplied to diagnose the pathological changes. Also get a conclusion: after thedomestic fowl meat is long to place the flexible characteristic parameter will change,and a new method for the food safety is be provided.
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