基于相位变换声镊的单个微粒平面移动操控

In-plane manipulation of single particle based on phase-modulating acoustic tweezer

声镊一般是指利用声辐射力原理对微小粒子进行悬浮和移动的一种技术.粒子的水平移动是声镊操控粒子的常见方式之一.本文理论推导了声辐射力与声压之间的直接关系,结果表明声压极大值点(聚焦点)与声辐射力势能的极小值点之间具有对应关系,并根据声阵列相位合成原理建立了声镊声场聚焦模型.文章基于数值仿真方法,以双侧16阵元声镊装置为例,分析了粒子水平移动的控制方法和稳定性.由于受到重力影响,粒子水平移动过程中必须考虑竖直方向的平衡问题.声场中,不同位置的粒子向各方向水平移动的稳定性是不同的.越靠近阵列中心,粒子移动的稳定性越高.粒子移动步长(精度)对移动稳定性也有重要影响.一般来说,步长越短稳定性越高.本模型中,移动步长减小1/2,稳定性提了高近40%.研究结果对于设计声镊粒子移动控制方法,规划粒子移动路径,推动声镊技术应用等具有理论意义.

The acoustic radiation force allows acoustic tweezers to suspend and move tiny particles.The horizontal movement is one of the common forms in which acoustic tweezers manipulate particles.In this paper,the direct relationship between acoustic radiation force and sound pressure is derived theoretically.The results show that there is a corresponding relationship between the maximum point of sound pressure(focus point)and the minimum point of acoustic radiation force potential energy.A model for focused acoustic field in acoustic tweezers is established based on the principle of phase modulating.In the numerical simulation,taking the double-sided 16-element acoustic tweezers device for example,the method of controlling the horizontal movement of particles and its stability are analyzed.Owing to the influence of gravity,the balance in the vertical direction must be considered in the horizontal movement of particles.Horizontal movement shows different stabilities at different positions in acoustic filed.The closer to the center of the array the particle is,the more stably it moves.The step length(accuracy)also has an important influence on the moving stability.In general,the shorter the step size is,the higher the stability is.In this model,when moving step length is reduced by one-half,the stability is improved by nearly 40%.The research results have theoretical significance for designing acoustic tweezers,planning particle movement paths,and promoting the application of acoustic tweezers technology.