Simulation Study Of Low-intensity Ultrasonic Acupuncture On Auricular Points

Auricular therapy,as a commonly used treatment method in Chinese medicine,has a significant effect on improving sleep disorders.In terms of operating methods,since there is less subcutaneous fat in the ear,auricular acupuncture is easy to damage cartilage and even cause auricle infection.Therefore,auricular acupuncture is often not used for auricular points in clinical practice,but the method of sticking ear beans is used.However,this method requires the patients to press it by hand to cooperate,which is not easy to quantify and standardize.Low-intensity ultrasound has the characteristics of good penetration ability,non-invasiveness,safety,and obvious biological effects such as mechanical,thermal and cavitation effects in biological tissues.It is very suitable for the treatment of special body parts such as auricular points.However,the "strength" of ultrasonic acupuncture acting on the auricular points is still not very clear,and clinical experience is lacking at present,which limits the promotion and application of ultrasonic acupuncture in clinical medicine.Therefore,this uses the finite element method to study the ultrasound field characteristics of auricular points and the temperature field and stress field generated when ultrasound is applied to the auricular points,laying a theoretical foundation for the further application of ultrasonic acupuncture in clinical practice.The main research contents are as follows:(1)Theoretical and finite element calculations are carried out on the focused ultrasound field of concave spherical transducer.Because the specific depth of auricular acupuncture is not quantified in clinical practice,this paper designs the transducer with hyperbolic pipe,which is a hyperbolic pipe that it is set at the ultrasound output end of the transducer.Through the finite element simulation analysis,it is found that the hyperbolic pipe has the effect of converging ultrasound beams.In addition,exploring the influence of the parameters of pipe shape on the ultrasound field distribution outside the pipe,and measuring the radial ultrasound field of the transducer with hyperbolic pipe.The results show that:the parameters of pipe shape effect the acoustic pressure outside the pipe.And when selecting the parameters of pipe shape,it is necessary to avoid high acoustic pressure at the nozzle.(2)Based on a finite element model of ultrasonic acupuncture acting on the auricular points,and using the biological tissue heat conduction equation and elastic wave equation,this analyzes the distribution of ultrasound field,temperature f eld and stress field formed by transducers(concave spherical transducer and the transducer with hyperbolic pipe)on the auricular points.The results show that the ultrasound intensity of the transducer with hyperbolic pipe is always lower than that of concave spherical transducer,and the axial size of the ultrasound concentrating area is larger and the ultrasound concentrating depth is deeper.It is further found that when the ultrasound stimulation time is longer(more than 16.98s),and the temperature rise of biological tissues caused by the former is higher.And the thermal stimulation caused by the former of auricular points is better.In addition,both transducers can produce stress concentration at the cartilage tissue,but concave spherical transducer produces greater stress.(3)The focused ultrasound generated by concave spherical transducer is applied to the auricular points as the stimulus source,and the finite element simulation is used to study the effects of the parameters of ultrasound and biological tissues on the ultrasound field,temperature field and stress field of auricular points.The results show that the ultrasound intensity of auricular points increases with the increase of the ultrasound frequency,and also increases with the increase of the emitted acoustic pressure of the transducer.And the temperature rise of auricular points increases as the ultrasound frequency increases;the temperature rise of auricular points increases as the acoustic pressure emitted by the transducer increases.Moreover,the axial size of the focal region decreases with the increase of the ultrasound frequency,and the position of the focal point moves away from the sound source as the ultrasound frequency increases.When low-intensity ultrasound focuses on the skin-cartilage interface,as the absorption coefficient of cartilage increases,the ultrasound intensity in cartilage and skin behind the cartilage decrease.The temperature rise of auricular points not only increases with the increase of the absorption coefficient of cartilage,but also increases with the increase of the thickness of cartilage.Further changing the focus position,when low-intensity ultrasound focuses on the cartilage,the ultrasound intensity and temperature rise at the focus are higher than the ultrasound intensity and temperature rise at the focus on the skin and the skin-cartilage interface.In addition,the stress concentration will occur at the cartilage tissue.And the stress value increases with the increase of the emitted acoustic pressure of the transducer,and maximum stress value reduces with the increase of the Young's modulus of the skin.However,the axial size of the stress concentration area remains unchanged with changes of the ultrasonic frequency,the emitted acoustic pressure of the transducer,and the Young's modulus of the skin.By applying low-intensity ultrasound to acupuncture of auricular points,the research results show that it can generate temperature rise and it produces stress concentration at the cartilage tissue.Moreover,the parameters of ultrasound and biological tissues affect the ultrasound field,temperature field,and stress field of auricular points.Therefore,in order to achieve the effect of ultrasonic acupuncture of auricular points to improve sleep,it is necessary to reasonably select the parameters of ultrasound and the ultrasound focusing method according to the actual situation,so as to make the treatment effect better.