Bazyar H, Kandemir M H, Peper J, Andrade M A B, Bernassau A L, Schroën K, Lammertink R G H
Engineering Thermodynamics, Process & Energy Department, Faculty of Mechanical, Maritime and Materials Engineering, Delft University of Technology, Leeghwaterstraat 39, 2628CB Delft, The Netherlands.
Department of Electrical Engineering and Automation, Aalto University, 02150 Espoo, Finland.
Biomicrofluidics. 2023 Dec 27;17(6):064107. doi: 10.1063/5.0175400. eCollection 2023 Dec.
Acoustic manipulation of particles in microchannels has recently gained much attention. Ultrasonic standing wave (USW) separation of oil droplets or particles is an established technology for microscale applications. Acoustofluidic devices are normally operated at optimized conditions, namely, resonant frequency, to minimize power consumption. It has been recently shown that symmetry breaking is needed to obtain efficient conditions for acoustic particle trapping. In this work, we study the acoustophoretic behavior of monodisperse oil droplets (silicone oil and hexadecane) in water in the microfluidic chip operating at a non-resonant frequency and an off-center placement of the transducer. Finite element-based computer simulations are further performed to investigate the influence of these conditions on the acoustic pressure distribution and oil trapping behavior. Via investigating the Gor'kov potential, we obtained an overlap between the trapping patterns obtained in experiments and simulations. We demonstrate that an off-center placement of the transducer and driving the transducer at a non-resonant frequency can still lead to predictable behavior of particles in acoustofluidics. This is relevant to applications in which the theoretical resonant frequency cannot be achieved, e.g., manipulation of biological matter within living tissues.
微通道中颗粒的声学操控近来备受关注。油滴或颗粒的超声驻波（USW）分离是一种成熟的微尺度应用技术。声流控装置通常在优化条件下运行，即共振频率，以最小化功耗。最近研究表明，需要打破对称性才能获得高效的声学颗粒捕获条件。在这项工作中，我们研究了在非共振频率下运行且换能器偏心放置的微流控芯片中，单分散油滴（硅油和十六烷）在水中的声泳行为。进一步进行了基于有限元的计算机模拟，以研究这些条件对声压分布和油滴捕获行为的影响。通过研究戈尔科夫势，我们在实验和模拟获得的捕获模式之间找到了重叠。我们证明，换能器的偏心放置以及在非共振频率下驱动换能器，仍可导致声流控中颗粒的可预测行为。这与无法达到理论共振频率的应用相关，例如对活组织内生物物质的操控。
