Research On Measurement Of Young’s Modulus Of Biological Tissue Based On Ultrasound

China’s aging population is becoming increasingly serious.More and more people are suffering from various diseases caused by visceral pathological change.Young’s modulus of biological tissue will be significantly different from that of normal tissue when pathological changes occur.Therefore,the measurement of Young’s modulus of biological tissue has important value.It can be used for diagnosis,treatment and prediction of cellular or tissue diseases.In this paper,a theoretical method for measuring the Young’s modulus of biological tissue has been studied.The method is quantitative,easy to operate,simple to program,and reliable.Based on theoretical derivation,a corresponding measurement scheme and device have been designed.Finally a feasible and reliable measurement of Young’s modulus of biological tissue has been achieved.Based on the basic principles of acoustics and mechanics,this paper confirmed the reliability,effectiveness,and accuracy of the measurement method through theoretical research and simulation verification.Firstly,the final expression of the Young’s modulus of biological tissue was reconstructed through theoretical formula derivation.The final expression was only related to measurable parameters.The derivation process was as follows: ultrasonic sensor I and sensor II were at a certain horizontal distance and immersed in the fluid level,placed horizontally above the biological tissue sample.At the same time,sensor I was also an excitation emission actuator.Sensor I and sensor II received the echo signals together.The ultrasonic excitation was unfocused,so the ultrasonic beams spread around.Sensor I received two significant echoes.Sensor II received three significant echoes.Each echo had a specific propagation path between the fluid and the tissue.Two sensors obtained the data of sound pressure and time of echo signals.According to the data,geometric relationship,ultrasonic Snell’s law,and characteristic relationship between sound pressure and impedance ratio,the density and longitudinal wave velocity of the sample tissue were calculated.Finally,the final expression of Young’s modulus was obtained by the characteristics of Poisson’s ratio of biological tissues.To verify the effectiveness and feasibility of the theoretical measurement method,this paper utilized the finite element software COMSOL for simulation verification.A total of 106 simulation groups was set up.Accurate and reliable Young’s modulus measurement results were obtained.Except for some limit cases,the Young’s modulus results of COMSOL had good accuracy.The changes of working conditions included the sample thickness,the horizontal distance between two sensors,the vertical distance between two sensors and the sample surface,and types of fluid medium.The summary results of each simulation group of COMSOL showed: when only the sample thickness,the horizontal distance,or the vertical distance were changed,it would create a specific limit situation that the error of Young’s modulus results increased significantly.To further validate the usability of theoretical methods,this paper utilized finite element software ABAQUS to conduct the same simulation verification,totaling 106 simulation groups.The Young’s modulus results of COMSOL and ABAQUS were consistent,so the same limit value conclusion could be summarized.The changes of fluid medium types did not affect the measurement of Young’s modulus of biological tissue.Therefore,the theoretical method was still suitable for measurement in different fluid media.To sum up,the ultrasonic measurement method in this paper is nondestructive,non-contact,long-distance and widely applicable.Compared with the existing ultrasonic methods of measuring Young’s modulus,the method in this paper has more advantages.It does not require other methods to obtain the density and thickness of the sample in advance.The density and thickness of the sample can be measured by ultrasonic method.Thus,the influence of multiple unknown parameters is eliminated.To some extent,it overcomes the difficulty of measurement of Young’s modulus by ultrasonic method under complex conditions.