How to steer active colloids up a vertical wall

Adérito Fins Carreira (1) , Adam Wysocki (2) , Christophe Ybert (1) , Mathieu Leocmach (1) , Heiko Rieger (2, 3) , Cécile Cottin-Bizonne (1)

1 ILM - Institut Lumière Matière [Villeurbanne]
2 Department of Theoretical Physics and Center for Biophysics, Saarland University
3 INM - Leibniz Institute for New Materials

An important challenge in active matter lies in harnessing useful global work from entities that produce work locally, e.g., via self-propulsion. We investigate here the active matter version of a classical capillary rise effect, by considering a non-phase separated sediment of self-propelled Janus colloids in contact with a vertical wall. We provide experimental evidence of an unexpected and dynamic adsorption layer at the wall. Additionally, we develop a complementary numerical model that recapitulates the experimental observations. We show that an adhesive and aligning wall enhances the pre-existing polarity heterogeneity within the bulk, enabling polar active particles to climb up a wall against gravity, effectively powering a global flux. Such steady-state flux has no equivalent in a passive wetting layer.

Mots clés: Active matter; Capillarity

Domaines: Matière Molle [cond-mat.soft]

Adérito Fins Carreira, Adam Wysocki, Christophe Ybert, Mathieu Leocmach, Heiko Rieger, et al.. How to steer active colloids up a vertical wall. 2023. ⟨hal-04282487v2⟩