Qin X P, Geng D L, Xie W J, Wei B
School of Physical Science and Technology, Northwestern Polytechnical University, Xi'an 710072, China.
Rev Sci Instrum. 2022 Jun 1;93(6):064506. doi: 10.1063/5.0093655.
Existing single-axis acoustic levitation devices with an axisymmetric reflector can manipulate particles in a variety of ways. However, the mechanism by which particles are suspended in a single-axis acoustic levitator with a non-axisymmetric reflector remains poorly understood. This work addresses this issue by proposing a novel single-axis ultrasonic levitator design that includes a flat plane emitter and a screw-plane reflector. The node positions of the standing wave formed in this levitator were predicted by calculating the Gor'kov potential according to a numerical model. The analysis results demonstrate that the nodes were distributed off-axis and their positions varied in a spiral manner when changing the distance between the emitter and reflector. Corresponding experiments based on the proposed design were also conducted, and the results indicated that the distance changes between the emitter and reflector could induce some spiral trajectories of a polyethylene-foam particle placed in the ultrasonic field. Moreover, the trajectory of the suspended particle was found to distribute along a conical surface centered on the central axis of this device. This work provides a new approach for ultrasonic particle manipulation by changing the geometry of the reflector.
现有的带有轴对称反射器的单轴声悬浮装置能够以多种方式操控粒子。然而，粒子在带有非轴对称反射器的单轴声悬浮器中悬浮的机制仍未得到充分理解。这项工作通过提出一种新颖的单轴超声悬浮器设计来解决这一问题，该设计包括一个平面发射器和一个螺旋面反射器。根据数值模型计算戈尔科夫势，预测了在此悬浮器中形成的驻波的节点位置。分析结果表明，节点分布在轴外，并且当改变发射器与反射器之间的距离时，它们的位置呈螺旋状变化。还基于所提出的设计进行了相应实验，结果表明发射器与反射器之间的距离变化会使置于超声场中的聚乙烯泡沫粒子产生一些螺旋轨迹。此外，发现悬浮粒子的轨迹沿以该装置中心轴为中心的圆锥面分布。这项工作通过改变反射器的几何形状为超声粒子操控提供了一种新方法。
