Issue |
EPL
Volume 140, Number 2, October 2022
|
|
---|---|---|
Article Number | 27001 | |
Number of page(s) | 7 | |
Section | Biological and soft matter physics | |
DOI | https://doi.org/10.1209/0295-5075/ac9c28 | |
Published online | 07 November 2022 |
Active colloids in harmonic optical potentials(a)
1 Institute for Experimental Physics of Condensed Matter, Heinrich-Heine-Universität Düsseldorf Universitätsstr. 1, 40225 Düsseldorf, Germany
2 Institute for Theoretical Physics II, Heinrich-Heine-Universität Düsseldorf - Universitätsstr. 1, 40225 Düsseldorf, Germany
3 Centre de Recherche Paul Pascal, University of Bordeaux - 115 Avenue du Dr Albert Schweitzer, 33600 Pessac, France
4 Laboratory for Soft Materials and Interfaces, ETH Zürich - Vladimir-Prelog-Weg 5, 8093 Zürich, Switzerland
(b) E-mail: Ivo.Buttinoni@hhu.de (corresponding author)
(c) E-mail: lorenzo.caprini@hhu.de
Received: 17 August 2022
Accepted: 20 October 2022
We study the motion of active Janus colloids in an optical trap using experiments, theory and numerical simulations. To achieve isotropic and harmonic confinement, we prototype microparticles with a nearly uniform refractive index and verify that, in the absence of activity, the confined motion is identical to that of optically homogeneous Brownian particles. If the activity is turned on by means of vertical AC fields, the density distributions are described by Boltzmann-like statistics (Gaussian with effective temperature) only for strongly confining traps, whereas weaker potentials give rise to non-Gaussian distributions with a bimodal shape. Our results showcase a simple way to study active soft matter in optical potential landscapes eliminating the optical torque.
© 2022 The author(s)
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