The contactless manipulation of microparticles and cells by using acoustic forces is important in many applications. However, multi-band acoustophoresis has been rarely investigated in the literature. In this Letter, we propose a microscale acoustofluidic system that has multiple orders of available Lamb modes for the acoustic trapping of microparticles at various frequencies. In our device, standing Lamb waves (SLWs) of specific orders can be selectively excited in a 300-μm-thick piezoelectric lithium-niobate (LiNbO₃) crystal plate by a pair of interdigitated transducers (IDTs) at the corresponding frequency. We demonstrate the acoustophoretic trapping and patterning of 7-μm particles in a single acoustofluidic device with multiple available actuating frequencies. The approach to the proposed design and the working mechanisms are explained by using thin plate and a full-wave models that solve the dispersion relations and coupling fields of the piezoelectric SLW acoustofluidic system, respectively. Furthermore, we experimentally show that the stable and tight trapping of particles in the chamber can be achieved independently along two mutually orthogonal directions. This provides the essential ground for planar manipulations of microparticles and cells based on the proposed device. The results here can trigger more innovative designs and applications of acoustofluidic devices for microparticle manipulation and microfluidic mixing, with multi-frequency channels and a wide span of different actuating frequencies in one system.

中文翻译：

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由兰姆驻波驱动的微流体室中微粒的声泳图案

通过使用声力对微粒和细胞进行非接触式操作在许多应用中都很重要。然而，文献中很少研究多波段声泳。在这封信中，我们提出了一种微型声流体系统，该系统具有多个可用的 Lamb 模式，用于在各种频率下对微粒进行声学捕获。在我们的设备中，特定阶数的兰姆驻波 (SLW) 可以在 300微米厚的压电铌酸锂 (LiNbO ₃ ) 晶体板中通过一对叉指换能器 (IDT) 以相应的频率选择性地激发。我们展示了 7- μ的声泳诱捕和图案化单个声流体装置中的 m 个粒子，具有多个可用的驱动频率。通过使用分别求解压电 SLW 声流体系统的色散关系和耦合场的薄板和全波模型来解释所提出的设计方法和工作机制。此外，我们通过实验表明，可以沿着两个相互正交的方向独立地实现对腔室中粒子的稳定和紧密捕获。这为基于所提出的设备对微粒和细胞进行平面操作提供了必要的基础。这里的结果可以触发用于微粒操纵和微流体混合的声流体装置的更多创新设计和应用，