Sarvazyan Armen, Ostrovsky Lev
ARTANN Laboratories, Inc, Trenton, New Jersey 08618, USA.
J Acoust Soc Am. 2009 Jun;125(6):3548-54. doi: 10.1121/1.3124769.
The possibility of using acoustic radiation force in standing waves for stirring and mixing small volumes of liquids is theoretically analyzed. The principle of stirring considered in this paper is based on moving the microparticles suspended in a standing acoustic wave by changing the frequency so that one standing wave mode is replaced by the other, with differently positioned minima of potential energy. The period-average transient dynamics of solid microparticles and gas microbubbles is considered, and simple analytical solutions are obtained for the case of standing waves of variable amplitude. It is shown that bubbles can be moved from one equilibrium position to another two to three orders of magnitude faster than solid particles. For example, radiation force in a standing acoustic wave field may induce movement of microbubbles with a speed of the order of a few m/s at a frequency of 1 MHz and ultrasound pressure amplitude of 100 kPa, whereas the speed of rigid particles does not exceed 1 cms under the same conditions. The stirring effect can be additionally enhanced due to the fact that the bubbles that are larger and smaller than the resonant bubbles move in opposite directions. Possible applications of the analyzed stirring mechanism, such as in microarrays, are discussed.
从理论上分析了利用驻波中的声辐射力搅拌和混合少量液体的可能性。本文所考虑的搅拌原理是基于通过改变频率来移动悬浮在驻波中的微粒，从而使一种驻波模式被另一种驻波模式所取代，这两种模式具有不同位置的势能极小值。考虑了固体微粒和气体微泡的周期平均瞬态动力学，并针对可变振幅驻波的情况得到了简单的解析解。结果表明，气泡从一个平衡位置移动到另一个平衡位置的速度比固体颗粒快两到三个数量级。例如，在1MHz频率和100kPa超声压力振幅下，驻波声场中的辐射力可能会使微泡以几m/s的速度移动，而在相同条件下刚性颗粒的速度不超过1cm/s。由于比共振气泡大的气泡和比共振气泡小的气泡向相反方向移动，搅拌效果可以进一步增强。讨论了所分析的搅拌机制的可能应用，如在微阵列中的应用。
