Department of Mechanical Engineering and Material Science, Duke University, NC 27708, USA.
Lab Chip. 2019 Oct 9;19(20):3397-3404. doi: 10.1039/c9lc00465c.
Contact-free manipulation of small objects (e.g., cells, tissues, and droplets) using acoustic waves eliminates physical contact with structures and undesired surface adsorption. Pioneering acoustic-based, contact-free manipulation techniques (e.g., acoustic levitation) enable programmable manipulation but are limited by evaporation, bulky transducers, and inefficient acoustic coupling in air. Herein, we report an acoustofluidic mechanism for the contactless manipulation of small objects on water. A hollow-square-shaped interdigital transducer (IDT) is fabricated on lithium niobate (LiNbO3), immersed in water and used as a sound source to generate acoustic waves and as a micropump to pump fluid in the ±x and ±y orthogonal directions. As a result, objects which float adjacent to the excited IDT can be pushed unidirectionally (horizontally) in ±x and ±y following the directed acoustic wave propagation. A fluidic processor was developed by patterning IDT units in a 6-by-6 array. We demonstrate contactless, programmable manipulation on water of oil droplets and zebrafish larvae. This acoustofluidic-based manipulation opens avenues for the contactless, programmable processing of materials and small biosamples.
使用声波对小物体（例如细胞、组织和液滴）进行无接触操作，可避免与结构发生物理接触和不必要的表面吸附。开创性的基于声的无接触操作技术（例如声悬浮）可实现可编程操作，但受到蒸发、体积庞大的换能器和空气耦合效率低下的限制。本文报道了一种在水面上对小物体进行非接触式操作的声流机理。在铌酸锂（LiNbO3）上制造了一个中空正方形叉指换能器（IDT），将其浸入水中，用作声源以产生声波，并用作微泵以在±x 和±y 正交方向上泵送流体。结果，可使漂浮在被激励 IDT 附近的物体沿定向声波传播方向在±x 和±y 方向上单向（水平）推动。通过在 6×6 阵列中对 IDT 单元进行图案化，开发了一种流体处理器。我们演示了在水面上对油滴和斑马鱼幼体进行无接触、可编程操作。这种基于声流的操作方法为对材料和小生物样本进行非接触、可编程处理开辟了途径。
