Department of Applied Physics, Northwestern Polytechnical University, Xi'an, 710072, China.
Department of Mechanical Engineering, University Walk, University of Bristol, Bristol, BS8 1TR, United Kingdom.
Sci Rep. 2017 Aug 2;7(1):7093. doi: 10.1038/s41598-017-07477-1.
Acoustic levitation in gaseous media provides a tool to process solid and liquid materials without the presence of surfaces such as container walls and hence has been used widely in chemical analysis, high-temperature processing, drop dynamics and bioreactors. To date high-density objects can only be acoustically levitated in simple standing-wave fields. Here we demonstrate the ability of a small number of peripherally placed sources to generate acoustic vortex fields and stably levitate a wide range of liquid and solid objects. The forces exerted by these acoustic vortex fields on a levitated water droplet are observed to cause a controllable deformation of the droplet and/or oscillation along the vortex axis. Orbital angular momentum transfer is also shown to rotate a levitated object rapidly and the rate of rotation can be controlled by the source amplitude. We expect this research can increase the diversity of acoustic levitation and expand the application of acoustic vortices.
在气态介质中，声悬浮提供了一种无需容器壁等表面存在即可处理固体和液体材料的工具，因此已广泛应用于化学分析、高温处理、液滴动力学和生物反应器中。迄今为止，只能在简单的驻波场中对高密度物体进行声悬浮。在这里，我们展示了少量外围放置的声源产生声涡旋场并稳定悬浮各种液体和固体物体的能力。观察到这些声涡旋场对悬浮水滴施加的力导致水滴可控变形和/或沿涡旋轴振动。还表明轨道角动量转移可以使悬浮物体快速旋转，并且旋转速率可以通过源幅度来控制。我们期望这项研究可以增加声悬浮的多样性，并扩展声涡旋的应用。
