Memoli Gianluca, Fury Christopher R, Baxter Kate O, Gélat Pierre N, Jones Philip H
Department of Acoustics, National Physical Laboratory, Hampton Road, Teddington TW11 0LW, United Kingdom.
Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom.
J Acoust Soc Am. 2017 May;141(5):3364. doi: 10.1121/1.4979933.
This work presents an acoustofluidic device for manipulating coated microbubbles, designed for the simultaneous use of optical and acoustical tweezers. A comprehensive characterization of the acoustic pressure in the device is presented, obtained by the synergic use of different techniques in the range of acoustic frequencies where visual observations showed aggregation of polymer-coated microbubbles. In absence of bubbles, the combined use of laser vibrometry and finite element modelling supported a non-invasive measurement of the acoustic pressure and an enhanced understanding of the system resonances. Calibrated holographic optical tweezers were used for direct measurements of the acoustic forces acting on an isolated microbubble, at low driving pressures, and to confirm the spatial distribution of the acoustic field. This allowed quantitative acoustic pressure measurements by particle tracking, using polystyrene beads, and an evaluation of the related uncertainties. This process facilitated the extension of tracking to microbubbles, which have a negative acoustophoretic contrast factor, allowing acoustic force measurements on bubbles at higher pressures than optical tweezers, highlighting four peaks in the acoustic response of the device. Results and methodologies are relevant to acoustofluidic applications requiring a precise characterization of the acoustic field and, in general, to biomedical applications with microbubbles or deformable particles.
这项工作展示了一种用于操控包覆微泡的声流控装置，该装置设计用于同时使用光学镊子和声学镊子。本文给出了该装置中声压的全面表征，这是通过在视觉观察显示聚合物包覆微泡聚集的声频范围内协同使用不同技术获得的。在没有气泡的情况下，激光测振法和有限元建模的联合使用支持了声压的非侵入式测量，并增进了对系统共振的理解。校准后的全息光学镊子用于在低驱动压力下直接测量作用于单个微泡的声学力，并确认声场的空间分布。这使得能够通过使用聚苯乙烯珠的粒子跟踪进行声压定量测量，并评估相关的不确定性。这个过程促进了对微泡跟踪的扩展，微泡具有负的声泳对比度因子，从而能够在比光学镊子更高的压力下对气泡进行声学力测量，突出了该装置声学响应中的四个峰值。结果和方法与需要对声场进行精确表征的声流控应用相关，并且总体上与涉及微泡或可变形颗粒的生物医学应用相关。
