Mechanical Effects Of Oscillating Microbubbles On Biological Tissues

The mechanical effects on biological tissues produced by beam microbubble oscillations have important medical applications in targeted drug delivery and opening of the blood-brain barrier.In this paper,from the perspective of biomechanics,a bubble-fluid-solid coupling dynamics model is created.Using finite element method,the interaction between oscillating microbubbles and the walls of biological tissues in the ultrasonic field is studied.The dynamic behavior of oscillating microbubbles in the vicinity of flat,convex and concave surfaces was studied respectively,focusing on the dynamic behavior of beam-receiving microbubbles in blood vessels,and the analysis of different sound frequencies,sound pressures,blood vessel scales and different initial Distribution of stress and strain on biological tissues under radius microbubbles.Calculations proves that: For the microbubble oscillation of the receiving beam in the blood vessel,when the frequency is 1.0-1.5MHz,the stress of the blood vessel wall decreases with the increase of the frequency;At 1.5-2.0MHz,the stress undergoes a half-sine wave change with frequency.After 2.0 MHz,the stress of microbubbles with different initial radii on the vessel wall tends to an equal stable value;When the frequency and initial microbubbles are determined,the stress of the vessel wall first increases and then decreases with the radius of the vessel.The thicker the vessel,the smaller the stress and vibration amplitude.Three kinds of microbubbles with different initial radii can produce corresponding maximum stresses in different vascular radii,and the microbubbles with smaller initial radius have the largest stress.When the microbubbles are close to the convex and concave tissue walls respectively,the microbubble oscillation will be weakened to varying degrees relative to the infinite uniform liquid,and will move closer to the wall with time,and the microbubble oscillation frequency will gradually increase.However,the deformation of the microbubbles near the rigid concave surface is more obvious,and it is easy to rupture to produce transient cavitation,and the pressure on the concave surface is relatively large,and the pressure on the convex surface is relatively small,and the stress is mainly concentrated on the bottom of the wall.As the radius of the groove increases,the peak stress on the wall decreases,but the depth of the stress increases.When the initial radius of the microbubble and the size of the concave surface are constant,the deformation of the groove is negatively correlated with the ultrasonic sound pressure and Young's modulus.When the acoustic parameters and the size of the concave surface are determined,the stress peak value and stress depth on the wall surface decrease correspondingly with the increase of the initial radius of the microbubble.When the oscillating microbubbles rupture,the maximum stress on the convex/concave wall surface is generated.This research model can be used to calculate the dynamic behavior of oscillating microbubbles and their biomechanical effects on biological tissues in different sizes of blood vessels,convex/concave tissue walls,for assessment of vascular damage,targeted drug therapy,and ultrasound thrombolysis.Provide theoretical reference in medicine.