Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes Forces
The acoustically-driven dynamics of isolated particle-like objects in microfluidic environments is a well-characterised phenomenon, which has been the subject of many studies. Conversely, very few acoustofluidic researchers looked at coated microbubbles, despite their widespread use in diagnostic im...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
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MDPI AG
2018-08-01
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| Series: | Micromachines |
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| Online Access: | http://www.mdpi.com/2072-666X/9/8/404 |
| _version_ | 1818570790588645376 |
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| author | Gianluca Memoli Kate O. Baxter Helen G. Jones Ken P. Mingard Bajram Zeqiri |
| author_facet | Gianluca Memoli Kate O. Baxter Helen G. Jones Ken P. Mingard Bajram Zeqiri |
| author_sort | Gianluca Memoli |
| collection | DOAJ |
| description | The acoustically-driven dynamics of isolated particle-like objects in microfluidic environments is a well-characterised phenomenon, which has been the subject of many studies. Conversely, very few acoustofluidic researchers looked at coated microbubbles, despite their widespread use in diagnostic imaging and the need for a precise characterisation of their acoustically-driven behaviour, underpinning therapeutic applications. The main reason is that microbubbles behave differently, due to their larger compressibility, exhibiting much stronger interactions with the unperturbed acoustic field (primary Bjerknes forces) or with other bubbles (secondary Bjerknes forces). In this paper, we study the translational dynamics of commercially-available polymer-coated microbubbles in a standing-wave acoustofluidic device. At increasing acoustic driving pressures, we measure acoustic forces on isolated bubbles, quantify bubble-bubble interaction forces during doublet formation and study the occurrence of sub-wavelength structures during aggregation. We present a dynamic characterisation of microbubble compressibility with acoustic pressure, highlighting a threshold pressure below which bubbles can be treated as uncoated. Thanks to benchmarking measurements under a scanning electron microscope, we interpret this threshold as the onset of buckling, providing a quantitative measurement of this parameter at the single-bubble level. For acoustofluidic applications, our results highlight the limitations of treating microbubbles as a special case of solid particles. Our findings will impact applications where knowing the buckling pressure of coated microbubbles has a key role, like diagnostics and drug delivery. |
| first_indexed | 2024-12-14T13:46:32Z |
| format | Article |
| id | doaj.art-caa639577c8b4f159faa23fdc4cee765 |
| institution | Directory Open Access Journal |
| issn | 2072-666X |
| language | English |
| last_indexed | 2024-12-14T13:46:32Z |
| publishDate | 2018-08-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Micromachines |
| spelling | doaj.art-caa639577c8b4f159faa23fdc4cee7652022-12-21T22:59:17ZengMDPI AGMicromachines2072-666X2018-08-019840410.3390/mi9080404mi9080404Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes ForcesGianluca Memoli0Kate O. Baxter1Helen G. Jones2Ken P. Mingard3Bajram Zeqiri4School of Engineering and Informatics, University of Sussex, BN1 9QJ Falmer, UKNational Physical Laboratory, TW11 0LW Teddington, UKNational Physical Laboratory, TW11 0LW Teddington, UKNational Physical Laboratory, TW11 0LW Teddington, UKNational Physical Laboratory, TW11 0LW Teddington, UKThe acoustically-driven dynamics of isolated particle-like objects in microfluidic environments is a well-characterised phenomenon, which has been the subject of many studies. Conversely, very few acoustofluidic researchers looked at coated microbubbles, despite their widespread use in diagnostic imaging and the need for a precise characterisation of their acoustically-driven behaviour, underpinning therapeutic applications. The main reason is that microbubbles behave differently, due to their larger compressibility, exhibiting much stronger interactions with the unperturbed acoustic field (primary Bjerknes forces) or with other bubbles (secondary Bjerknes forces). In this paper, we study the translational dynamics of commercially-available polymer-coated microbubbles in a standing-wave acoustofluidic device. At increasing acoustic driving pressures, we measure acoustic forces on isolated bubbles, quantify bubble-bubble interaction forces during doublet formation and study the occurrence of sub-wavelength structures during aggregation. We present a dynamic characterisation of microbubble compressibility with acoustic pressure, highlighting a threshold pressure below which bubbles can be treated as uncoated. Thanks to benchmarking measurements under a scanning electron microscope, we interpret this threshold as the onset of buckling, providing a quantitative measurement of this parameter at the single-bubble level. For acoustofluidic applications, our results highlight the limitations of treating microbubbles as a special case of solid particles. Our findings will impact applications where knowing the buckling pressure of coated microbubbles has a key role, like diagnostics and drug delivery.http://www.mdpi.com/2072-666X/9/8/404microbubblesacoustofluidicsBjerknes forcescompressibility |
| spellingShingle | Gianluca Memoli Kate O. Baxter Helen G. Jones Ken P. Mingard Bajram Zeqiri Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes Forces Micromachines microbubbles acoustofluidics Bjerknes forces compressibility |
| title | Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes Forces |
| title_full | Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes Forces |
| title_fullStr | Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes Forces |
| title_full_unstemmed | Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes Forces |
| title_short | Acoustofluidic Measurements on Polymer-Coated Microbubbles: Primary and Secondary Bjerknes Forces |
| title_sort | acoustofluidic measurements on polymer coated microbubbles primary and secondary bjerknes forces |
| topic | microbubbles acoustofluidics Bjerknes forces compressibility |
| url | http://www.mdpi.com/2072-666X/9/8/404 |
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