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Acoustic trapping of active matter

Takatori, Sho C. and De Dier, Raf and Vermant, Jan and Brady, John F. (2016) Acoustic trapping of active matter. Nature Communications, 7 . Art. No. 10694. ISSN 2041-1723. PMCID PMC4792924.

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Confinement of living microorganisms and self-propelled particles by an external trap provides a means of analysing the motion and behaviour of active systems. Developing a tweezer with a trapping radius large compared with the swimmers’ size and run length has been an experimental challenge, as standard optical traps are too weak. Here we report the novel use of an acoustic tweezer to confine self-propelled particles in two dimensions over distances large compared with the swimmers’ run length. We develop a near-harmonic trap to demonstrate the crossover from weak confinement, where the probability density is Boltzmann-like, to strong confinement, where the density is peaked along the perimeter. At high concentrations the swimmers crystallize into a close-packed structure, which subsequently ‘explodes’ as a travelling wave when the tweezer is turned off. The swimmers’ confined motion provides a measurement of the swim pressure, a unique mechanical pressure exerted by self-propelled bodies.

Item Type:Article
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URLURL TypeDescription CentralArticle
Takatori, Sho C.0000-0002-7839-3399
Brady, John F.0000-0001-5817-9128
Additional Information:© 2016 Macmillan Publishers Limited. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder to reproduce the material. To view a copy of this license, visit Received 23 October 2015; Accepted 13 January 2016; Published 10 March 2016. S.C.T. is supported by a Gates Millennium Scholars fellowship and a National Science Foundation (NSF) Graduate Research Fellowship (No. DGE-1144469). R.D.D. is supported by a doctoral fellowship of the fund for scientific research (FWO-Vlaanderen). This work is also supported by NSF Grant CBET 1437570. Author contributions: All authors participated in designing the project and performing the research. S.C.T. and R.D.D. performed the experiments and numerical simulations. All authors participated in writing the paper. The authors declare no competing financial interests.
Funding AgencyGrant Number
Gates Millennium Scholars fellowshipUNSPECIFIED
NSF Graduate Research FellowshipDGE-1144469
Fonds Wetenschappelijk Onderzoek - Vlaanderen (FWO)UNSPECIFIED
NSFCBET 1437570
Bill and Melinda Gates FoundationUNSPECIFIED
PubMed Central ID:PMC4792924
Record Number:CaltechAUTHORS:20160315-100739165
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Official Citation:Takatori, S. C. et al. Acoustic trapping of active matter. Nat. Commun. 7:10694 doi: 10.1038/ncomms10694 (2016).
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:65356
Deposited By: Tony Diaz
Deposited On:15 Mar 2016 19:11
Last Modified:24 Feb 2020 10:30

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