Dynamically stable optical trapping of thermophoretically active Janus colloids

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Hauptverfasser: Halder, Sanatan, Khan, Manas
Format: Preprint
Veröffentlicht: 2025
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author Halder, Sanatan
Khan, Manas
author_facet Halder, Sanatan
Khan, Manas
contents The ability to optically trap and manipulate artificial microswimmers such as active Janus particles (JPs) provides a breakthrough in active matter research and applications. However, it presents significant challenges because of the asymmetry in the optical properties of JPs and remains incomprehensible. Illustrating the interplay between optical and thermophoretic forces, we demonstrate dynamically stable optical trapping of Pt-silica JPs, where the force-balanced position evolves spontaneously within a localized volume around the focal point and in a vertically shifted annular confinement at low and high laser powers, respectively. Intriguingly, the orientational and orbital dynamics of JP remain strongly coupled in the delocalized confinement. Furthermore, we demonstrate simultaneous optical trapping of multiple JPs. This first report on thermophoresis of Pt-silica JPs and localized-to-delocalized crossover in the position distributions of an optically trapped active JP, verifying theoretical predictions, advances our understanding on confined active matter and their experimental realizations.
format Preprint
id arxiv_https___arxiv_org_abs_2509_21088
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Dynamically stable optical trapping of thermophoretically active Janus colloids
Halder, Sanatan
Khan, Manas
Soft Condensed Matter
Applied Physics
Optics
The ability to optically trap and manipulate artificial microswimmers such as active Janus particles (JPs) provides a breakthrough in active matter research and applications. However, it presents significant challenges because of the asymmetry in the optical properties of JPs and remains incomprehensible. Illustrating the interplay between optical and thermophoretic forces, we demonstrate dynamically stable optical trapping of Pt-silica JPs, where the force-balanced position evolves spontaneously within a localized volume around the focal point and in a vertically shifted annular confinement at low and high laser powers, respectively. Intriguingly, the orientational and orbital dynamics of JP remain strongly coupled in the delocalized confinement. Furthermore, we demonstrate simultaneous optical trapping of multiple JPs. This first report on thermophoresis of Pt-silica JPs and localized-to-delocalized crossover in the position distributions of an optically trapped active JP, verifying theoretical predictions, advances our understanding on confined active matter and their experimental realizations.
title Dynamically stable optical trapping of thermophoretically active Janus colloids
topic Soft Condensed Matter
Applied Physics
Optics
url https://arxiv.org/abs/2509.21088