Acoustic force measurements on polymer-coated microbubbles in a microfluidic device

Memoli, Gianluca, Fury, Christopher R, Baxter, Kate O, Gélat, Pierre N and Jones, Philip H (2017) Acoustic force measurements on polymer-coated microbubbles in a microfluidic device. Journal of the Acoustical Society of America, 141 (5). pp. 3364-3378. ISSN 0001-4966

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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.

Item Type: Article
Additional Information: work was funded by the National Physical Laboratory Strategic Research Fund
Keywords: Sound pressure, Acoustofluidics, Bubble dynamics, Optical tweezers, Acoustic instrumentation
Schools and Departments: School of Engineering and Informatics > Informatics
Research Centres and Groups: Creative Technology
Subjects: Q Science > QC Physics > QC0221 Acoustics. Sound
R Medicine > R Medicine (General) > R856 Biomedical engineering. Electronics. Instrumentation
T Technology > T Technology (General)
Depositing User: Gianluca Memoli
Date Deposited: 19 May 2017 11:05
Last Modified: 19 Nov 2017 02:00

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